Chapter 10 Anatomy and Physiology

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FIGURE 10.4 Neck Muscles

(a) Anterior neck muscles.

FIGURE 10.21 Anterior Muscles Attaching the Upper Limb to the Body

(a) Anterior pectoral muscles. (Names of muscles attaching the upper limb to the body are in bold.) (b) Cadever photo showing anterior pectoral muscles.

FIGURE 10.10 Hyoid Muscles

(a) Anterior superficial hyoid muscles.

FIGURE 10.33 Right Anterior Lateral Leg Muscles

(a) Anterior view of the right leg. (b) Lateral view of the right leg.

FIGURE 10.12 Muscles of the Palate, Pharynx, and Larynx

(a) Anterior-inferior view of the palate. The palatoglossus and part of the palatopharyngeus muscles are cut on one side to reveal the deeper muscles.

FIGURE 10.18 Anterior Abdominal Wall Muscles

(a) Cross section superior to the umbilicus.

FIGURE 10.31 Right Posterior Thigh Muscles

(a) Hip muscles are removed, showing the hamstrings.

FIGURE 10.19 Muscles of the Pelvic Diaphragm and Perineum

(a) Male pelvic diaphragm and perineum. (b) Female pelvic diaphragm and perineum. (Muscle names are in bold.)

FIGURE 10.5 Posterior Neck Muscles

(a) Posterior neck muscles.

FIGURE 10.22 Posterior Muscles Attaching the Upper Limb to the Body.

(a) Posterior view of muscles of the left posterior pectoral region.

FIGURE 10.28 Right Anterior Hip and Thigh Muscles

(a) Right anterior hip and thigh muscles.

FIGURE 10.26 Posterior Right Forearm Muscles

(a) Right forearm (superficial).

FIGURE 10.25 Anterior Right Forearm Muscles

(a) Right forearm (superficial). The brachioradialis muscle is removed.

FIGURE 10.29 Right Posterior Hip Muscles

(a) Right hip, superficial muscles

FIGURE 10.35 Right Foot Muscles

(a) Superficial muscles of the right foot. The plantar aponeurosis is cut. (b) Deep muscles of the right foot. The flexor digitorum brevis and flexor hallucinate longus are cut. (Muscle names are in bold.)

FIGURE 10.27 Right Hand Muscles

(a) Superficial muscles of the right hand. The abductor policies brevis is cut.

FIGURE 10.34 Right Posterior Leg Muscles

(a) Surface anatomy of the posterior right leg.

FIGURE 10.9 Muscles of Mastication

(a) The masseter and zygomatic arch are cut away to expose the temporalis.

FIGURE 10.20 Muscles Acting on the Scapula

(a) The trapezius is removed on the right side to reveal the deeper muscles.

FIGURE 10.17 Anterior Abdominal Wall Muscles

(a) Windows in the side reveal the various muscle.

FIGURE 10.13 Muscles That Move the Right Eyeball

(a) superior view of muscle in the eye orbit.

FIGURE 10.24 Lateral Right Arm Muscles

(a, b) The right shoulder and arm

FIGURE 10.24 Lateral Right Arm Muscles

(a, b) The right shoulder and arm.

FIGURE 10.18 Anterior Abdominal Wall Muscles

(b) Abdominal muscles show individually. (Muscle names are in bold.)

FIGURE 10.10 Hyoid Muscles

(b) Anterior deep hyoid muscles.

FIGURE 10.27 Right Hand Muscles

(b) Deep muscles of the right hand. The flexor digitorum tendons are cut.

FIGURE 10.26 Posterior Right Forearm Muscles

(b) Deep muscles of the right posterior forearm. The extensor digitorum, extensor digitized minimized, and extensor carpi ulnas muscles are cut to reveal deeper muscles.

FIGURE 10.13 Muscles That Move the Right Eyeball

(b) Lateral view of muscles in the eye orbit. (Names of muscles of eye movements are in bold.)

FIGURE 10.12 Muscles of the Palate, Pharynx, and Larynx

(b) Lateral view of the palate, pharynx, and larynx. Part of the mandible has been removed to reveal the deeper structures. (Muscle names in bold are muscles of swallowing and tongue movement.)

FIGURE 10.28 Right Anterior Hip and Thigh Muscles

(b) Photograph of the right anterior thigh muscles in a cadaver.

FIGURE 10.22 Posterior Muscles Attaching the Upper Limb to the Body.

(b) Posterior view of a cadever.

FIGURE 10.25 Anterior Right Forearm Muscles

(b) Right forearm (deeper than a). The pronator teres, flexor carpi radials and ulnas, and palmaris longus muscles are removed.

FIGURE 10.29 Right Posterior Hip Muscles

(b) Right hip, deep muscles. The gluteus Maximus and medius are removed to reveal deeper muscles.

FIGURE 10.34 Right Posterior Leg Muscles

(b) Superficial muscles.

FIGURE 10.17 Anterior Abdominal Wall Muscles

(b) Surface anatomy of anterior abdominal muscle.

FIGURE 10.4 Neck Muscles

(b) Surface anatomy of anterior neck muscles (Muscle names are in bold.)

FIGURE 10.5 Posterior Neck Muscles

(b) Surface anatomy of posterior neck muscles. (Muscles names are in bold.)

FIGURE 10.31 Right Posterior Thigh Muscles

(b) Surface anatomy of the posterior lower limb

FIGURE 10.9 Muscles of Mastication

(b) The masseter and temporalis muscles are removed, and the zygomatic arch and part of the mandible are cut away to reveal the deeper muscles.

FIGURE 10.20 Muscles Acting on the Scapula

(b) The pectoralis major is removed on both sides. The pectoralis minor is removed on the right side.

FIGURE 10.9 Muscles of Mastication

(c) Frontal section of the skull, showing the pterygoid muscles (Muscle names in bold are those involved in mastication.)

FIGURE 10.10 Hyoid Muscles

FIGURE 10.20 Muscles Acting on the Scapula

FIGURE 10.17 Anterior Abdominal Wall Muscles

FIGURE 10.33 Right Anterior Lateral Leg Muscles

FIGURE 10.26 Posterior Right Forearm Muscles

FIGURE 10.34 Right Posterior Leg Muscles

FIGURE 10.25 Anterior Right Forearm Muscles

(c) Right forearm (deeper than a or b). The brachioradialis, pronator teres, flexor carpi radials and ulnas, palmaris longs, and flexor digitorum superficially muscles are removed.

FIGURE 10.21 Anterior Muscles Attaching the Upper Limb to the Body

FIGURE 10.27 Right Hand Muscles

FIGURE 10.28 Right Anterior Hip and Thigh Muscles

FIGURE 10.29 Right Posterior Hip Muscles

FIGURE 10.22 Posterior Muscles Attaching the Upper Limb to the Body.

FIGURE 10.24 Lateral Right Arm Muscles

FIGURE 10.5 Posterior Neck Muscles

FIGURE 10.34 Right Posterior Leg Muscles

(d) Posterior view of the right calf, deep muscles. The gastrocnemius, planters, and soles muscles are removed. (Muscle names are in bold.)

FIGURE 10.29 Right Posterior Hip Muscles

(d) Right posterior hip muscles as viewed in a cadaver. (Muscle names are in bold).

FIGURE 10.26 Posterior Right Forearm Muscles

(d) Surface anatomy of posterior forearm. (Muscle names are in bold.)

FIGURE 10.33 Right Anterior Lateral Leg Muscles

(d) Surface anatomy of the posterolateral leg. (Muscle names are in bold.)

FIGURE 10.21 Anterior Muscles Attaching the Upper Limb to the Body

(d) Surface anatomy of the right anterior pectoral region. (Names of the upper limb muscles are in bold.)

FIGURE 10.24 Lateral Right Arm Muscles

(d) Surface anatomy of the right shoulder and arm.

FIGURE 10.25 Anterior Right Forearm Muscles

(d). Surface anatomy of anterior forearm muscles. (Muscle names are in bold.)

To visualize how these muscle groups work together, imagine that you want to raise your arm so that your hand is high above your head.

1. Abduct your arm from the anatomical position through 90 degrees (to the point at which the hand is level with the shoulder); this involves moving the humerus and is accomplished by the deltoid muscle assisted by the rotator cuff muscles, which hold the head of the humerus tightly in place. In the initial phase of abduction, the deltoid is assisted by the supraspinatus. Place your hand on your deltoid, and feel it contract as you abduct 90 degrees. 2. Next, move your arm from 90 degrees to 180 degrees, so that your hand is high above your head; this movement primarily involves rotation of the scapula, which is accomplished by the trapezius and serratus anterior muscles. Feel the inferior angle of your scapula as you abduct your arm to 90 degrees and then rotate to 180 degrees. Do you notice difference? Bear in mind that your arm cannot move from 90 degrees to 180 degrees unless the head of the humerus is held tightly in the glenoid cavity by the rotator cuff muscles, especially the supraspinatus. Damage to the supraspinatus muscle can prevent abduction past 90 degrees.

What are the seven characteristics that give muscles names?

1. Location 2.Size 3.Shape 4.Orientation of fascicles 5.Origin and insertion 6.Number of heads 7.Function.

List the criteria used to name muscles, and give an example of each.

1. Location. A pectoralis (chest) muscle is located in the chest, a gluteus (buttock) muscle is in the buttock, and a brachial (arm) muscle is in the arm. 2. Size. The gluteus Maximus (large) is the largest muscle of the buttock, and the gluteus minimus (small) is the smallest. A longus (long) muscle is longer than a braves (short) muscle. In addition, a second part to the name immediately tells us there is more than one related muscle. For example, if there is a breviss muscle, most likely a longus muscle is present in the same area. 3. Shape. The deltoid (triangular) muscle is triangular in shape, a Quadratus (quadrate) muscle is rectangular, and a teres (round) muscle is round. 4. Orientation of fascicles. A rectus (straight, parallel) muscle has muscle fascicles running in the same direction as the structure with which the muscle is associated whereas the fascicles of an oblique muscle lie at an angle to the length of the structure. 5. Origin and insertion. The sternocleidomastoid has its origin on the sternum and clavicle and its insertion on the mastoid process of the temporal bone. The brachioradialis originates in the arm (brachium) and inserts onto the radius. 6. Number of heads. A biceps muscle has two heads (origins), and a triceps muscle has three heads (origins). 7. Function. Recall from chapter 8 that body movements have names, for example, abduction and adduction. Abductors and adductors are the muscles that cause that type of movement. Abduction moves a structure away from the midline, and adduction moves a structure toward the midline.

Number of heads.

A biceps muscle has two heads (origins), and a triceps muscle has three heads (origins).

What usually causes ptosis on one side? Which muscles are responsible for puckering the lips, smiling, sneering, and frowning? What causes a dimple of the chin?

A droopy eyelid on one side, called ptosis, usually indicates that the nerve to the levator palpebrae superioris, or the part of the brain controlling that nerve, has been damaged. 1. The orbicularis oris and buccinator, the kissing muscles, pucker the mouth. 2. Smiling is accomplished by the zygomaticus major and minor, the levator anguli oris, and the risorius. 3. Sneering is accomplished by the levator labii superioris. 4. Frowning or pouting is achieved by the depressor anguli oris, the depressor labii inferioris, the mentalis. If the mentalis muscles are well developed on each side of the chin, a chin dimple, where the skin is tightly attached to the underlying bone or other connective tissue, may appear between the two muscles.

Location.

A pectoralis (chest) muscle is located in the chest, a gluteus (buttock) muscle is in the buttock, and a brachial (arm) muscle is in the arm.

Orientation of fascicles

A rectus (straight, parallel) muscle has muscle fascicles running in the same direction as the structure with which the muscle is associated, whereas the fascicles of an oblique muscle lie at an angle to the length of the structure.

What is the extensor retinaculum?

A strong ring of fibrous connective tissue, the extensive retinaculum, encircles the flexor and extensor tendons to hold them in place around the wrist, so that they do not "bowstring" (pull away from the bone) during muscle contraction.

How is abduction of the fingers accomplished ?

Abduction of the fingers is accomplished by the dorsal interossei and the abductor digiti minimi.

How is adduction acomplished.

Adduction is a function of the palmar interossei.

Summary of Muscle Actions on the Hip and Thigh Adduction

Adductor magnus Adductor longus Adductor brevis Pectineus Gracilis

Give an example of class III lever system.

An example is a person using a shovel. The hand placed on the part of the handle closest to the blade provides the pull to lift the weight, such as a shovelful of dirt, and the hand placed near the end of the handle acts as the fulcrum

Give an example of the class II lever system.

An example is a wheelbarrow; the wheel is the fulcrum, and the person lifting on the handles provides the pull. The weight, or load, carried in the wheelbarrow is placed between the wheel and the operator.

FIGURE 10.23 Right Rotator Cuff Muscles

Anterior view of the rotator cuff. (Muscle names are in bold.)

What are tendons?

At the attachment point, tendons connect each muscle to the bone. Tendons are composed of dense connective tissue and can be long and ropelike, broad and sheetlike or very short.

What are bipennate muscles?

Bipennate muscles have fascicles arranged on two sides of the tendon.

What can help you remember the muscles.

Breaking the muscles into groups of actions and then practicing actions on yourself will help you remember the details of each muscle.

Pattern of Fascicle Arrangement: Convergent

Broadly disturbed fascicles converge at a single tendon. Examples: Pectoralis major Pectoralis minor

What does mastication involve?

Chewing, or mastication, involves forcefully closing the mouth and grinding food between the teeth of the mandible. These activities are carried out by the muscles of mastication and the hyoid muscles.

What geometric shapes can muscle have?

Circle, triangular, trapezium, rhomboidal, quadrate

What are circular muscles?

Circular muscles have their fascicles arranged in a circle around an opening and act as sphincters (constrictors) to close the opening. Examples of circular muscles are those that surround the eyes, called the orbicularis oculi, and those that surround the mouth, called the orbicularis oris.

Describe the three classes of levers, and give an example of each type in the body.

Class I: The fulcrum (F) is located between the weight (W) and the pull (P), or force. The pull is directed downward, and the weight, on the opposite side of the fulcrum, is lifted. In the body, the fulcrum extends through several cervical vertebrae. Class II: The weight (W) is located between the fulcrum (F) and the pull (P), or force. The upward pull lifts the weight. The movement of the mandible is easier to compare to a wheelbarrow if the head is considered upside down. Class III: The pull (P), or force, is located the fulcrum (F) and the weight (W). The upward pull lifts the weight.

What decreases the volume of the abdominal cavity and the thoracic cavity?

Contraction of the abdominal muscle when the vertebral column is stationary decreases the volume of the abdominal cavity and the thoracic cavity and can aid in such functions as forced expiration, vomiting, defecation, coughing, and childbirth.

What are convergent muscles?

Convergent muscles have fascicles that join at one common tendon from a wide area, which creates muscles that are triangular in shape. Having fibers that lie side by side can result in muscles with less strength if the total number of fibers is low. However, if the fibers are long, these muscles can have a large range of motion. One example of convergent muscles with many long fibers is the pectoralis muscles of the chest

FIGURE 10.15 Vertebral Muscles

Deep muscles associated with the vertebrae are shown. (Muscle names are in bold.)

Summary of Muscle Actions on the Shoulder Flexion:

Deltoid Pectoralis major Coracobrachialis Biceps brachii

Summary of Muscle Actions on the Shoulder and Arm Extension:

Deltoid Teres major Latissimus dorsi Pectoralis major Triceps brachii

Summary of Muscle Actions on the Shoulder and Arm Lateral Rotation:

Deltoid Infraspinatus Teres minor

Summary of Muscle Actions on the Shoulder and Arm Abduction:

Deltoid Supraspinatus

What happens during pregnancy?

During pregnancy, the muscles of the pelvic diaphragm and the urogenital triangle may be stretched by the extra weight of the fetus, and specific exercises are designed to strengthen them.

What are arms attached to the thorax by?

Each of our arms is attached to the thorax by several muscles, including the pectoralis major and the latissimus dorsi.

What do the four rectus muscles attach to?

Each of the four rectus (straight) muscles attaches to the eyeball anterior to the center of the sphere. 1. The superior rectus rotates the anterior portion of the eyeball superiorly, so that the pupil, and thus the gaze, is directed superiorly (looking up). 2. The inferior rectus depresses the gaze. 3.The lateral rectus laterally deviates (abducts) the gaze (looking on the side). 4. The medial recuts medially deviates (adducts) the gaze (looking toward the nose)>

What muscles help move food into the mouth?

Even though the muscles of the tongue and the buccinator are not involved in chewing, they help move the food and hold it in place between the teeth.

What do everyday movements involve?

Everyday movements involve skeletal muscles contracting to pull one bone of a joint toward another bone of the same joint. However, not all muscles are attached to bone at both ends.

How is extension accomplished by the four medial digits?

Extension is accomplished by the extensor digitorum. The tendons of this muscle are very visible on the dorsal of the hand.

How extension of the wrist and fingers accomplished?

Extension of the wrist and fingers, such as when opening a fist, is accomplished by most of the posterior forearm muscles.

How is extension of the wrist accomplished?

Extension of the wrist is through the action of three posterior forearm muscles, (1) the extensor carpi radialis longus, (2) the extensor carpi radialis brevis, and (3) the extensor carpi ulnaris.

Pattern of Fascicle Arrangement: Multipennate

Fascicles are arranged at many places around the central tendon. They are spread out at angles to many smaller tendons. Example: Deltoid

Pattern of Fascicle Arrangement: Circular

Fascicles are arranged in a circle around an opening and act as sphincters to close the opening. Examples: Orbicularis oris Obricularis oculi

Pattern of Fascicle Arrangement: Bipennate

Fascicles are on both sides of the tendon. Example: Rectus femoris

Pattern of Fascicle Arrangement: Parallel

Fascicles lie parallel to one another and to the long axis of the muscle. Examples: Trapezius Rhomboideus Rectus abdominis

Pattern of Fascicle Arrangement: Fusiform

Fascicles lie parallel to the long axis of the muscle. The belly of the muscle is larger in diameter than the ends. Example: Biceps brachii (two headed; shown) Triceps brachii (thee-headed)

Pattern of Fascicle Arrangement: Pennate Unipennate

Fascicles originate from a tendon that runs the length of the entire muscle. There are three different patters. Fascicles are on only one side of the tendon. Example: Palmar interosseus Semimembranous

Muscle: Perineum Urogenital triangle Bulbospongiosus

Female-central tendon of perineum Insertion: Base of clitoris Nerve: Pudendal Action: Erects clitoris

What movement do the fibularis muscles have in common? The tibialiss muscles?

Fibularis muscles both help evert and plantar flex the foot. Tiabialis muscles help flex and invert the foot.

List the muscles that cause flexion and extension of the elbow. Where are these muscles located?

Flexion of elbow -Biceps brachii Anterior arm -Brachialis Lateral arm -Brachioradialis lateral and inferior to biceps brachii Extension of elbow -Triceps brachii Posterior arm -Anconeus Posterior or lateral elbow

What muscle cause flexion and extension of the shoulder? Adduction and abduction of the arm? What muscle abducts the arm to 90 degrees? Above 90 degrees?

Flexion of shoulder -Deltoid -Pectoralis major -Coracobrachialis -Biceps brachii Extension of shoulder -Deltoid -Teres major -Latissimus dorsi -Pectoralis major -Triceps brachii Adduction of arm: -Pectoralis major -Latissimus dorsi -Teres major -Teres minor -Triceps brachii -Coracobrachialis Abduction of arm: -Deltoid -Siupraspinatus 1.Abduct your arm from the anatomical position through 90 degrees (to the point at which the hand is level with the shoulder); this involves moving the humerus and is accomplished by the deltoid muscle assisted by the rotator cuff muscles, which hold the head of the humerus tightly in place. In the initial phase of abduction, the deltoid is assisted by the supraspinatus. Place your hand on your deltoid, and feel it contract as you abduct 90 degrees. 2. Next, move your arm from 90 degrees to 180 degrees, so that your hand is high above your head; this movement primarily involves rotation of the scapula, which is accomplished by the trapezius and serratus anterior muscles.

What is the flexion of the four medial digits a function of?

Flexion of the four medial digits is a function of (1) the flexor digitorum superficially and (2) the flexor digitorum profundus.

How is flexion of the wrist and fingers accomplished?

Flexion of the wrist and fingers, such as when making a fist, is accomplished by most of the anterior forearm muscles.

How is flexion of the wrist accomplished?

Flexion of the wrist is accomplished by two major anterior forearm muscles, (1) the flexor carpi radialis and (2) the flexor carpi ulnaris.

Describe the muscle groups that cause flexion and extension of the wrist.

Flexion of the wrist is accomplished by two major anterior forearm muscles, (1) the flexor carpi radialis and (2) the flexor carpi ulnaris. Extension of the wrist is through the action of three posterior forearm muscles, (1) the extensor carpi radialis longus, (2) the extensor carpi radialis brevis, and (3) the extensor carpi ulanris.

Give an example of weight can affect body movement.

For example, only a very small shift in weight is needed for one child to lift the other on a seesaw. However, a class I lever is quite limited as to how much weight can be lifted and how high it can be lifted. For example, consider what happens when the child on one end of the seesaw is much larger than the child on the other end.

Give an example of agonists and antagonists.

For example, the biceps brachii flexes (bends) the elbow, and the triceps brachii extends the elbow. In the example of elbow flexion, the biceps brachii is the agonist (flexes), whereas the triceps brachii is the antagonist (extends). When extending the elbow, the muscles' roles are reversed; the triceps brachii is the agonist and the biceps brachii is the antagonist. Most joints in the body have agonist and antagonist groups or pairs.

Give an example of how muscles work in groups.

For example, the deltoid, biceps brachii, and pectorals major all help flex the shoulder. Furthermore, many muscles are members of more than one group, depending on the type of movement being produced. for example, the anterior part of the deltoid muscle functions with the flexors of the shoulder, whereas the posterior part functions with the extensors of the shoulder. In elbow flexion, the biceps brachii and the brachial are synergists. However, the brachial muscle is more important for elbow flexion than the biceps brachii.

Give an example of prime movers and fixators.

For example, the origin of a prime mover is often stabilized by fixators, so that its action occurs at its point of insertion. When moving the humerus, the muscles of the scapula act as fixators to hold the scapula in space.

Give an example of muscles have more than one origin.

For example, the triceps brachii has three origins that join together to form one muscle.

How many groups of thoracic muscles are associated with the rib cage?

Name the muscle that is mainly responsible for respiratory movements. What other muscles aid this movement?

Four major groups of thoracic muscles are associated with the rib cage, which helps air flow into the lungs. Changes in the diameter of the rib cage are important for determining airflow into and out of the lungs. The scalene muscles elevate the first two ribs during more forceful inspiration. The external intercostals elevate the ribs during quiet, resting inspiration. The internal intercostals and transversus thoracis muscles depress the ribs during forced expiration.

How is frowning or pouting achieved?

Frowning or pouting is achieved by the depressor anguli oris, the depressor labii inferioris, and the mentalis. If the mentalist muscles are well developed on each side of the chin dimple, where the skin is tightly attached to the underlying bone or other connective tissue, may appear between the two muscles.

What are Fusiform muscles?

Fusiform muscles are those whose fascicles run the length of the entire muscle and taper at each end to terminate at tendons. Fusiform muscles have a wider belly than the ends of the muscle. Because their fibers are long, but are commonly numerous, these muscles generally tend to be stronger than other muscles with parallel fascicle arrangements.

Name the leg muscles that flex the knee. Which of them can also plantar flex the foot?

Gastrocnemius Plantaris Popliteus The plantaris can flex the foot

Summary of Muscle Actions on the Hip and Thigh Abduction

Gluteus maximus Gluteus medius Gluteus minimus Tensor fascia latae Obturator internus Gemellus superior and inferior Piriformis

Summary of Muscle Actions on the Hip and Thigh Lateral Rotation

Gluteus maximus Obturator internus Obturator externus Superior gemellus Inferior gemellus Quadratus femoris Piriformis Adductor Magnus Adductor longus Adductor brevis

Summary of Muscle Actions on the Hip and Thigh Extension

Gluteus maximus Semitendinosus Semimembranosus Biceps femoris Adductor Magnus

What happens if both sternocleidomastoid muscles contract?

If both contract together, they flex the neck (chin to chest).

What happens if sternocleidomastoid muscle flexes on one side?

If the sternocleidomastoid muscle on only one side of the neck contracts, the neck is rotated toward the opposite side.

What happens if the suprahyoid muscles fix?

If the suprahyoid muscles fix the hyoid and thus stabilize it from above, the thyrohyoid muscle (an infrahyoid muscle) can elevate the larynx. To observe this effect, place your hand on your larynx (Adam's apple) and swallow.

What happens if the dome or phrenic nerve controlling the diaphragm is severely damaged?

If this dome of skeletal muscle or the phrenic nerve controlling it is severely damaged, the amount of air moving into and out of the lungs may be so small that the individual cannot survive without the aid of an artificial respirator.

Summary of Muscle Actions on the Hip and Thigh Flexion

Iliopsoas Tensor fascia latae Sartorius Adductor longus Adductor brevis Pectineus

Describe class I lever system.

In a class I lever system, the fulcrum is between the pull and the weight. A child's seesaw is this type of lever. The children on the seesaw alternate between being the weight and being the pull across a fulcrum in the center of the board.

Describe a class II lever system.

In a class II lever system, the weight is located between the fulcrum and the pull.

Explain class III lever system.

In a class III lever system, the most common type in the body, the pull is between the fulcrum and the weight.

What is prime mover?

In a group of synergists, the muscle that contributes most to the movement is called the prime mover. The brachialis is the prime mover in elbow flexion.

What is the linea alba?

In a relatively muscular person with little body fat, a vertical line called the line alba, or white line, is visible. It is an area consisting of only dense regular connective tissue. The line alba extends from the diploid process of the sternum through the navel to the pubis.

Where do some muscles of the thigh originate?

In addition to the hip muscles, some of the muscles located in the thigh originate on the hip bone and can cause movement of the thigh.

What are fixators?

In some groups of synergists, the prime mover needs to be stabilized. The stabilizers of prime movers are called fixators. Usually, a fixator holds one bone in place relative to the body while a more distal bone is moved.

What is muscle strength related to?

In summary, muscle strength is primarily related to total fascicle number in muscle, whereas range of motion is correlated to fascicle arrangement. Muscles with parallel fibers have the largest range of motion.

Describe class I lever system in the body?

In the body, movement of the head to look up, such as at the night sky, is this type of lever. The atlantoocipital joint in the neck is the fulcrum (F). The posterior neck muscles provide the pull (P) by depressing the back of the head, which is the weight (W). With the weight balanced over the fulcrum, only a small amount of pull is required to lift the weight.

Describe class III lever system in the body.

In the body, the action of the biceps brachii muscle (force) pulling on the radius (lever) to flex the elbow (fulcrum) and elevate the hand (weight) is a class III lever. This type of lever system does not allow as great a weight to be lifted, but it can be lifted a greater distance.

Describe how joints, bones and muscles work together in the body.

In the body, the joints function as fulcrums, the bones function as levers, and muscles provide the force.

Describe class II lever system in the body

In the body, there are relatively few examples of class II levers. Depressing the mandible when you open your mouth is one example. Another is your entire body when doing push-ups-your toes are the fulcrum, your body is the weight, and your arms provide the pull (force).

What is the head?

In the case of multiple origins, each origin is called a head.

What are unipennate muscles?

In unipennate muscles, the fascicles are on one side of the tendon.

Describe the muscles of the eye and the movements they produce.

Inferior Oblique= elevates and laterally moves eye Superior Oblique= Depresses and laterally moves ey Inferior Rectus= Depresses and medially moves ey Lateral Rectus= Laterally moves eye Medial Rectus= Medially moves ey Superior Rectus= Elevates and medially moves eye

List the general actions performed by intrinsic foot muscles.

Intrinsic foot muscles, located within the foot itself, flex, extend, abduct, and adduct the toes. They are arranged in a manner similar to that of the intrinsic muscles of the hand.

What are intrinsic foot muscles?

Intrinsic foot muscles, located within the foot itself, flex, extend, abduct, and adduct the toes. They are arranged in a manner similar to that of the intrinsic muscles of the hand.

What is the perineum?

Just inferior to (beneath) the pelvic diaphragm is a diamond-shaped area called the perineum.

How is lateral flexion of the neck accomplished?

Lateral flexion of the neck (moving the head back to the midline after it has been tilted to one side) is accomplished by the lateral flexors of the opposite side.

What is the linea semilunaris?

Lateral to the recuts abdominis is the linea semilunaris ( a cresent- or half-moon-shaped line); lateral to it are three layers of muscle. From superficial to deep, these muscles are the external abdominal oblique, internal abdominal oblique, and transverses abdominis.

What are levers?

Levers are machines that consist of a rigid pole or beam that can pivot, or move, at a stationary hinge.

What muscle cause rotation of the arm?

Medial Rotation -Pecotralis major -Teres major -Latissimus dorsi -Deltoid -Subscapularis Lateral Rotation -Deltoid -Infraspinatus -Teres minor

What do most laryngeal muscles do?

Most of the laryngeal muscles help narrow or close the laryngeal opening, so that food does not enter the larynx when a person swallows. The remaining muscles shorten (relax) the vocal cords to lower the pitch of the voice or lengthen (tense) the vocal cords to raise the pitch of the voice.

Where are most skeletal muscle attached to?

Most skeletal muscles are attached to bones. They extend from bone to bone across the linking joint.

How is movement of the thumb and little finger accomplished?

Movement of the thumb and little finger is accomplished by two groups of muscles called the thenar eminence and the hyopthenar eminence.

Describe the muscles that move the thumb. The tendons of what muscles form the anatomical snuffbox?

Movement of the thumb is caused in part by three muscles: (1) the abductor policis longus, (2) the extensor policis longus, and (3) the extensor policis brevis. These tendons form the sides of a depression on the posterolateral side of the wrist called the "anatomical snuffbox". When snuff was in use, a small pinch could be placed into the anatomical snuffbox and inhaled through the nose.

How is movement of the thumb caused?

Movement of the thumb is caused in part by three muscles: (1) the abductor pollicis longus, (2) the extensor pollicis longus, and (3) the extensor pollicis brevis.

What are multipennate muscles?

Multipennate muscles are those with fascicles arranged at many places around the central tendon.

How do muscles function?

Muscles also tend to function in groups to accomplish specific movements. The muscles of the group are called synergists.

What do muscles and their bones perform?

Muscles and their bones perform work together through levers.

Using the terms fulcrum, lever, and force, explain how contraction of a muscle result in movement.

Muscles and their bones perform work together through levers. Levers are machines that consist of a rigid pole or beam that can pivot, or move, at a stationary hinge. The hinge is called a fulcrum (F). The lever moves at the hinge and can apply force to a weight (W). There are three classes, or types, of levers based not the location of the fulcrum, weight, and force along the lever. In the body, the joints function as fulcrums, the bones function as levers, and muscles provide the force. When muscles contract, the pull (P), or force, of muscle contraction is applied to the levers (bones), causing them to move a body part (the weight). In figure 10.2, you can see that the three classes of levers are classes I, II, and III.

FIGURE 10.1 Muscle Attachment and Movements

Muscles are attached to bones by tendons. The biceps brachii has two heads, which originate on the scapula. The triceps brachii has three heads, which originate on the scapula and the humerus. The biceps brachii inserts onto the radial tuberosity and onto nearby connective tissue. The triceps brachii inserts onto the olecranon process of the ulna.

How are muscles studied?

Muscles are typically studied in groups called agonists and antagonists. The action of a single muscle or group of muscles (agonist) is opposed by that of another muscle or group of muscles (antagonist).

FIGURE 10.6 Posterior Deep Neck Muscles

Muscles deep to the trapezius are shown in this figure.

FIGURE 10.7 Facial Muscles

Muscles involved in facial expressions are shown in this figure. (Bold terms denote the muscles involved in facial expression.)

What is the abdomis recuts?

On each side of the line alba is the rectus abdominis, surrounded by a rectus sheath.

FIGURE 10.14 Deep Neck and Back Muscles

On the right of this figure, the erector spinae group of muscles is shown. On the left o this figure, these muscles are removed to reveal the deeper back muscles (Names of muscles of the neck and back are in bold.)

What does opening the mouth wide require?

Opening the mouth wide requires the action of the depressors of the mandible (lateral pterygoid, digastric, geniohyoid, mylohyoid).

Muscle: Medial Compartment Adductor Magnus

Origin: Adductor part: pubis and ischium Hamstring part: ischial tuberosity Insertion: Adductor part: linea aspera of femur Hamstring part: adductor tubercle of femur Nerve: Adductor part: obturator Hamstring part: tibial Action: Adductor part: adducts thigh and flexes hip Hamstring part: Extends hip and adducts thigh

Muscle: Circothyroid

Origin: Anterior cricoid cartilage Insertion: Thyroid cartilage Nerve: Superior laryngeal Action: Lengthens (tenses) vocal cords

Muscle: Anterior Compartment Sartorius

Origin: Anterior superior iliac spine Insertion: Medial side of tibial tuberosity Nerve: Femoral Action: Flexes hip and knee; rotates thigh laterally and leg medially.

Muscle: Posterior and Lateral Tensor fascia latae

Origin: Anterior superior iliac spine Insertion: Through iliotibial tract to lateral condyle of tibia Nerve: Superior gluteal Action: Tenses lateral fascia and stabilizes femur on tibia when standing; flexes hip; abducts and medially rotates thigh; tilts pelvis

Muscle: Arm Brachialis

Origin: Anterior surface of humerus Insertion: Ulnar tuberosity and coronoid process of ulna Nerve: Musculocutaneous and radial Action: Flexes elbow

Muscle: Larynx Arytenoids Oblique

Origin: Arytenoid cartilage Insertion: Opposite arytenoid cartilage Nerve: Recurrent laryngeal Action: Narrows opening to larynx

Muscle: Larynx Transverse

Origin: Arytenoid cartilage Insertion: Opposite arytenoid cartilage Nerve: Recurrent laryngeal Action: Narrows opening to larynx

Muscle: Posterior Oblique capitis

Origin: Atlas Insertion: Occipital bone (inferior nuchal line) Nerve: Dorsal remus of C1 Action: Extends and laterally flexes neck; turns head

Muscle: Salpingopharyngeus

Origin: Auditory tube Insertion: Pharynx Nerve: Pharyngeal plexus Action: Elevates pharynx; opens auditory tube in swallowing

Muscle: Posterior Rectus capitis posterior

Origin: Axis, atlas Insertion: Occipital bone Nerve: Dorsal ramus of C1 Action: Extends and rotates neck; turns head

Muscle: Suprahyoid Muscles Mylohyoid

Origin: Body of mandible Insertion: Hyoid Nerve: Mandibular division of trigeminal Action: Elevates floor of mouth and tongue; depresses mandible when hyoid is fixed

Muscle: Procerus

Origin: Bridge of nose Insertion: Frontalis Nerve: Facial Action: Creates horizontal wrinkles between eyes, as in frowning

Muscle: Lateral Scalene muscles

Origin: C2-C6 Insertion: First and second ribs Nerve: Cervical and brachial plexuses Action: Flex, laterally flex, and rotate neck.

Muscle: Posterior Semispinalis capitis

Origin: C4-T6 Insertion: Occipital bone Nerve: Dorsal rami of cervical nerves Action: Extends, rotates, and laterally flexes neck

Muscle: Spinalis Cervicis

Origin: C6-C7 Insertion: Spinous processes of C2-C3 Nerve: Dorsal rami of cervical nerves Action: Extends neck

Muscle: Abductor hallucis

Origin: Calcaneus Insertion: Base of proximal phalanx of great toe Nerve: Medial plantar Action: Abducts great toe

Muscle: Extensor digitorum brevis

Origin: Calcaneus Insertion: Four tendons fused with tendons of extensor digitorum longus Nerve: Deep fibular Action: Extends toes

Muscle: Abductor digiti minimi

Origin: Calcaneus Insertion: Proximal phalanx of fifth toe Nerve: Lateral plantar Action: Abducts and flexes little toe

Muscle: Quadratus plantae

Origin: Calcaneus Insertion: Tendons of flexor digitorum longus Nerve: Lateral plantar Action: Assists flexor digitorum longus in flexing lateral four toes.

Muscle: Flexor digitorum brevis

Origin: Calcaneus and plantar fascia Insertion: Four tendons to middle phalanges of four lateral toes Nerve: Medial plantar Action: Flexes lateral four toes

Muscle: Pectoralis major

Origin: Clavicle sternum, superior six costal cartilages, and abdominal aponeurosis Insertion: Lateral crest of intertubercular groove Nerve: Medial and lateral pectoral Action: Flexes shoulder; adducts and medially rotates arm; extends shoulder from flexed position

Muscle: Perineum Anal triangle External anal sphincter

Origin: Coccyx Insertion: Central tendon of perineum Nerve: Fourth sacral and pudendal Action: Keeps orifice of anal canal closed; relaxes during defecation.

Muscle: Oblique Superior

Origin: Common tendinous ring Insertion: Scelra of eye Nerve: Trochlear Action: Depresses and laterally moves eye

Muscle: Rectus Lateral

Origin: Common tendinous ring Insertion: Sclera of eye Nerve: Abducens Action: Medially moves eye

Muscle: Rectus Inferior

Origin: Common tendinous ring Insertion: Sclera of eye Nerve: Oculomotor Action: Depresses and medially moves eye

Muscle: Rectus Medial

Origin: Common tendinous ring Insertion: Sclera of eye Nerve: Oculomotor Action: Medially moves eye

Muscle: Rectus Superior

Origin: Common tendinous ring Insertion: Sclera of eye Nerve: Oculomotor Action: Elevates and medially moves eye

Muscle: Coracobrachialis

Origin: Coracoid process of scapula Insertion: Midshaft of humerus Nerve: Musculocutaneous Action: Adducts arm and flexes shoulder

Muscle: Flexor hallucis brevis

Origin: Cuboid; medial and lateral cuneiforms Insertion: Two tendons to proximal phalanx of great toe Nerve: Medial and lateral plantar Action: Flexes great toe

Muscle: Deltoid

Origin: Deltoid tuberosity Insertion: Deltoid tuberosity Nerve: Axillary Action: Flexes and extends shoulder; abducts and medially and laterally rotates arm.

Muscle: Forearm Pronator qudratus

Origin: Distal ulna Insertion: Distal radius Nerve: Anterior interosseous Action: Pronates forearm (and hand)

Muscle: Trapezius

Origin: External occipital protuberance, ligaments nuchal, and spinous processes of C7-T12 Insertion: Clavicle, acromion process, and scapular spine Nerve: Accessory and cervical plexus Action: Elevates, depresses, retracts, rotates, and fixes scapula; extends neck.

Muscle: Platysma

Origin: Fascia of deltoid and pectoralis major Insertion: Skin over inferior border of mandible Nerve: Facial Action: Depresses lower lip; wrinkles skin of neck and upper chest; to express fear

Muscle: Posterior Compartment Plantaris

Origin: Femur Insertion: Through calcaneal tendon to calcaneus Nerve: Tibial Action: Plantar flexes foot; flexes knee

Muscle: Posterior Compartment Flexor hallucis longus

Origin: Fibula Insertion: Distal phalanx of great toe Nerve: Tibial Action: Flexes great toe; plantar flexes and inverts foot

Muscle: Anterior Compartment Fibularis tertius

Origin: Fibula and interosseous membrane Insertion: Fifth metatarsal bone Nerve: Deep fibular Action: Dorsiflexes and everts foot

Muscle: Posterior Compartment Soleus

Origin: Fibula and tibia Insertion: Through calcaneal tendon to calcaneus Nerve: Tibial Action: Plantar flexes foot

Muscle: Flexor digiti minimi brevis

Origin: Fifth metatarsal bone Insertion: Proximal phalanx of digit 5 Nerve: Lateral plantar Action: Flexes little toe (proximal phalanx)

Muscle: Anterior External abdominal oblique

Origin: Fifth to twelfth ribs Insertion: Iliac crest, inguinal ligament, and rectus sheath Nerve: Branches of lower thoracic Action: Flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

Muscle: Subclavius

Origin: First rib Insertion: Clavicle Nerve: Subclavian Action: Fixes clavicle or elevates first rib

Muscle: Serratus anterior

Origin: First to eighth or ninth ribs Insertion: Medial border of scapula Nerve: Long thoracic Action: Rotates and protracts scapula; elevates ribs

Muscle: Thenar Muscles Flexor pollicis brevis

Origin: Flexor retinaculum and first metacarpal bone Insertion: Proximal phalanx of thumb Nerve: Median and ulnar Action: Flexes thumb

Muscle: Thenar Muscles Abductor pollicis brevis

Origin: Flexor retinaculum, trapezium and scaphoid Insertion: Proximal phalanx of thumb Nerve: Median Action: Abducts thumb

Muscle: Hypothenar Muscles Opponens digiti minimi

Origin: Hamate and flexor retinaculum Insertion: Fifth metacarpal bone Nerve: Ulnar Action: Opposes little finger

Muscle: Extrinsic Muscles Hyoglossus

Origin: Hyoid Insertion: Side of tongue Nerve: Hypoglossal Action: Retracts and depresses side of tongue

Muscle: Posterior Quadratus lumborum

Origin: Iliac crest and lower lumbar vertebrae Insertion: Twelfth rib and upper lumbar vertebrae Nerve: Upper lumbar Action: Laterally flexes vertebral column and depresses twelfth rib

Muscle: Anterior Internal abdominal oblique

Origin: Iliac crest, inguinal ligament, and lumbar fascia Insertion: Tenth to twelfth ribs and rectus sheath Nerve: Lower thoracic Action: Flexes and rotates vertebral column; compresses abdominal wall; depresses thorax

Muscle: Anterior Iliopsoas Iliacus

Origin: Iliac fossa Insertion: Lesser trochanter of femur and capsule of hip joint Nerve: Lumbar plexus Action: Flexes hip

Muscle: Intercostals External

Origin: Inferior margin of each rib Insertion: Superior border of next rib below Nerve: Intercostal Action: Quiet inspiration elevates ribs

Muscle: Deep Thigh Rotators Obturator Externus

Origin: Inferior margin of obturator foramen Insertion: Greater trochanter of femur Nerve: Obturator Action: Laterally rotates thigh

Muscle: Superficial Erector spina divides into three columns Illiocostalis Thoracis

Origin: Inferior six ribs Insertion: Superior six ribs Nerve: Dorsal rami of thoracic nerves Action: Extends, laterally flexes, and rotates vertebral column

Muscle: Lateral Compartment Fibularis brevis

Origin: Inferior two-thirds of lateral fibula Insertion: Fifth metatarsal bone Nerve: Superficial fibular Action: Everts and plantar flexes foot

Muscle: Rotator Cuff Infraspinatus

Origin: Infraspinous fossa of scapula Insertion: Greater tubercle of humerus Nerve: Suprascapular C5 and C6 Action: Laterally rotates arm; holds head of humerus in place

Muscle: Obturator Internus

Origin: Interior margin of obturator foramen Insertion: Greater trochanter of femur Nerve: L5 and S1 Action: Laterally rotates thigh

Muscle: Diaphragm

Origin: Interior of ribs, sternum, and lumbar vertebrae Insertion: Central tendon of diaphragm Nerve: Phrenic Action: Inspiration depresses floor of thorax

Muscle: Perineum Transverse perineal muscle Superficial

Origin: Ischial ramus Insertion: Central perineal Nerve: Pudendal Action: Fixes central tendon

Muscle: Perineum Ischiocavernosus

Origin: Ischial ramus Insertion: Corpus cavernosum Nerve: Perineal Action: Compresses base of penis or clitoris

Muscle: Perineum Transverse perineal muscle Deep

Origin: Ischial ramus Insertion: Median raphe Nerve: Pudendal Action: Supports pelvic floor

Muscle: Pelvic Diaphragm Coccygeus

Origin: Ischial spine Insertion: Coccyx Nerve: S3 and S4 Action: Forms pelvic floor; supports pelvic organs

Muscle: Deep Thigh Rotators Gemelus Superior

Origin: Ischial spine Insertion: Obturator internus tendon Nerve: L5 and S1 Action: Laterally rotates and abducts thigh

Muscle: Obturator Quadrates femoris

Origin: Ischial tuberosity Insertion: Intertrochanteric ridge of femur Nerve: L5 and S1 Action: Laterally rotates thigh

Muscle: Posterior Compartment Semimembranosus

Origin: Ischial tuberosity Insertion: Medial condyle of tibia and collateral ligament Nerve: Tibial Action: Flexes knee; medially rotates leg; tenses capsule of knee joint; extends hip

Muscle: Deep Thigh Rotators Gemellus Inferior

Origin: Ischial tuberosity Insertion: Obturator internus tendon Nerve: L5 and S1 Action: Laterally rotates and abducts thigh

Muscle: Posterior Compartment Semitendinosus

Origin: Ischial tuberosity Insertion: Tibia Nerve: Tibial Action: Flexes knee; medially rotates leg; extends hip

Muscle: Rotator Cuff Teres minor

Origin: Lateral border of scapula Insertion: Greater tubercle of humerus Nerve: Axillary C5 and C6 Action: Laterally rotates and adducts arm; holds head of humerus in place.

Teres major

Origin: Lateral border of scapula Insertion: Medial crest of inter tubercular groove Nerve: Lower sub scapular C5 and C6 Action: Extends shoulder; adducts and medially rotates arm

Muscle: Anterior Compartment Extensor digitorum longus

Origin: Lateral condyle of tibia and fibula Insertion: Four tendons to phalanges of four lateral toes Nerve: Deep fibular Action: Extends four lateral toes; dorsiflexes and everts foot

Muscle: Posterior Forearm Extensor carpi radialis brevis

Origin: Lateral epicondyle of humerus Insertion: Base of third metacarpal bone Nerve: Radial Action: Extends and abducts wrist

Muscle: Forearm Anconeus

Origin: Lateral epicondyle of humerus Insertion: Olecranon process and posterior ulna Nerve: Radial Action: Extends elbow

Muscle: Posterior Foreram Extensor digiti minimi

Origin: Lateral epicondyle of humerus Insertion: Phalanges of digit 5 Nerve: Radial Action: Extends fingers and wrist

Muscle: Posterior Forearm Extensor carpi ulnaris

Origin: Lateral epicondyle of humerus and ulna Insertion: Base of fifth metacarpal bone Nerve: Radial Action: Extends and adducts wrist

Muscle: Forearm Supinator

Origin: Lateral epicondyle of humerus and ulna Insertion: Radius Nerve: Radial Action: Supinates forearm (and hand)

Muscle: Posterior Compartment Popliteus

Origin: Lateral femoral condyle Insertion: Posterior tibia Nerve: Tibial Action: Flexes knee; medially rotates leg

Muscle: Adductor hallucis

Origin: Lateral four metatarsal bones Insertion: Proximal phalanx of great toe Nerve: Lateral plantar Action: Adducts great toe

Muscle: Cricoarytenoids Lateral

Origin: Lateral side of circoid cartilage Insertion: Arytenoid cartilage Nerve: Recurrent laryngeal Action: Narrows opening to larynx

Muscle: Pterygoids Lateral

Origin: Lateral side of lateral pterygoid plate and greater wing of sphenoid Insertion: Condylar process of mandible and articular disk Nerve: Mandibular division of trigeminal Action: Depresses and protracts mandible; involved in excursion; side-to-side movements.

Muscle: Posterior Forearm Extensor radialis longus

Origin: Lateral supracondylar ridge of humerus Insertion: Base of second metacarpal bone Nerve: Radial Action: Extends and abducts wrist

Muscle: Forearm Brachioradialis

Origin: Lateral supracondylar ridge of humerus Insertion: Styloid process of radius Nerve: Radial Action: Flexes elbow

Muscle: Levator palpebrae superioris

Origin: Lesser wing of sphenoid Insertion: Skin of eyelid Nerve: Oculomotor Action: Elevates upper eyelid; opens eye

Muscle: Posterior Compartment Biceps femoris

Origin: Long head--ischial tuberosity Short head-femur Insertion: Head of fibula Nerve: Long head-tibial Short head-common fibular Action: Flexes knee; laterally rotates leg; extends hip

Muscle: Arm Triceps brachii

Origin: Long head-infraglenoid tubercle on lateral border of scapula Lateral head--lateral and posterior surface of humerus Medial head-posterior humerus Insertion: Olecranon process of ulna Nerve: Radial Action: Extends elbow; extends shoulder and adducts arm

Muscle: Arm Biceps brachii

Origin: Long head-supraglenoid tubercle Short head- coracoid process Insertion: Radial tuberosity and aponeurosis of biceps brachii Nerve: Musculocutaneous Action: Flexes shoulder and elbow; supinates forearm and hand

Muscle: Depressor labii inferioris

Origin: Lower border of mandible Insertion: Skin of lower lip and orbicularis oris Nerve: Facial Action: Depresses lower lip

Muscle: Depressor anguli oris

Origin: Lower border of mandible Insertion: Skin of lower lip and orbicularis oris Nerve: Facial Action: Lowers corner of mouth; "frown"

Muscle: Perineum Urogenital triangle Bulbospongiosus

Origin: Male-central tendon of perineum and median raphe of penis Insertion: Dorsal surface of penis and bulb of penis Nerve: Pudendal Action: Compresses base of penis; ejects urine or semen; erects penis

Muscle: Mentalis

Origin: Mandible Insertion: Skin of chin Nerve: Facial Action: Elevates and wrinkles skin one chin; protrudes lower lip; "pout"

Muscle: Buccinator

Origin: Mandible and maxilla Insertion: Orbicularis oris at corner of mouth Nerve: Facial Action: Draws corners of mouth posteriorly; compresses cheek to hold food between teeth

Muscle: Infrahyoid Muscles Sternothyroid

Origin: Manubrium and first or second costal cartilage Insertion: Thyroid cartilage Nerve: Upper cervical through ansa cervicalis Action: Depresses larynx; fixes hyoid when opening mouth

Muscle: Lateral Sternocleidomastoid

Origin: Manubrium and medial clavicle Insertion: Mastoid process and superior nuchal line Nerve: Accessory (cranial nerve XI) Action: One contracting alone: laterally flexes head and neck to same side and rotates head and neck to opposite side Both contracting together: flex neck.

Muscle: Suprahyoid Muscles Digastric

Origin: Mastoid process (posterior belly) Insertion: Mandible near midline (anterior belly) Nerve: Posterior belly-facial; anterior belly-mandibular division of trigeminal Action: Depresses and retracts mandible; elevates hyoid

Muscle: Nasalis

Origin: Maxilla Insertion: Bridge and side of nose Nerve: Facial Action: Dilates nostril

Muscle: Levator labii superioris

Origin: Maxilla Insertion: Sides of nostrils (aloe) and upper lip Nerve: Facial Action: Elevates sides of nose and upper lip

Muscle: Levator anguli oris

Origin: Maxilla Insertion: Skin at corner of mouth and orbicularis oris Nerve: Facial Action: Raises corner of mouth

Muscle: Orbicularis oculi

Origin: Maxilla and frontal bones Insertion: Circles orbit and inserts near origin Nerve: Facial Action: Closing eyes; blinking, winking, squinting

Muscle: Posterior Compartment Superficial Gastrocnemius

Origin: Medial and lateral condyles of femur Insertion: Through calcaneal (Achilles) tendon to calcaneus Nerve: Tibial Action: Plantar flexes foot; flexes knee

Muscle: Anterior Forearm Palmaris longus

Origin: Medial epicondyle of humerus Insertion: Palmar fascia Nerve: Median Action: Tenses palmar fascia; flexes wrist

Muscle: Anterior Forearm Flexor carpi radialis

Origin: Medial epicondyle of humerus Insertion: Second and third metacarpal bones Nerve: Median Action: Flexes and abducts wrist

Muscle: Pronator teres

Origin: Medial epicondyle of humerus and coronoid process of ulna Insertion: Radius Nerve: Median Action: Pronates forearm (and hand)

Muscle: Anterior Forearm Flexor carpi ulnaris

Origin: Medial epicondyle of humerus and ulna Insertion: Pisiform, hamate, and fifth metacarpal bones Nerve: Ulnar Action: Flexes and adducts wrist

Muscle: Anterior Forearm Flexor digitorum superficialis

Origin: Medial epicondyle of humerus, coronoid process, and radius Insertion: Middle phalanges of digits 2-5 Nerve: Median Action: Fixes fingers at interphalangeal joints and wrist

Muscle: Pharynx Pharyngeal constrictors Superior

Origin: Medial pterygoid plate, mandible, floor of mouth, and side of tongue Insertion: Pharyngeal raphe Nerve: Pharyngeal plexus Action: Narrows superior portion of pharynx in swallowing

Muscle: Pterygoids Medial

Origin: Medial side of lateral pterygoid plate and tuberosity of maxilla Insertion: Medial surface of mandible Nerve: Mandibular division of trigeminal Action: Elevates and protracts mandible; involved in excursion; side-to-side movements

Muscle: Suprahyoid Muscles Geniohyoid

Origin: Mental protuberance of mandible Insertion: Body of hyoid Nerve: Fibers of C1 and C2 with hypoglossal Action: Protracts hyoid; depresses mandible

Muscle: Extrinsic Muscles Genioglossus

Origin: Mental protuberance of mandible Insertion: Tongue Nerve: Hypoglossal Action: Depresses and protrudes tongue

Muscle: Dorsal interossei

Origin: Metatarsal bones Insertion: Proximal phalanges of digits 2, 3, and 4 Nerve: Lateral plantar Action: Abduct second, third, and fourth toes

Muscle: Anterior Compartment Extensor hallucis longus

Origin: Middle fibula and interosseous membrane Insertion: Distal phalanx of great toe Nerve: Deep fibular Action: Extends great toe; dorsiflexes and inverts foot

Muscle: Corrugator supercilli

Origin: Nasal bridge and orbiculares oculi Insertion: Skin of eyebrow Nerve: Facial Action: Dresses medial portion of eyebrow, draw eyebrows together, as in frowning.

Muscle: Orbicularis oris

Origin: Nasal septum, maxilla, and mandible Insertion: Fascia and other muscles of lips Nerve: Facial Action: Closes and purses lips; "kissing"

Muscle: Occipitofrontalis

Origin: Occipital bone Insertion: Skin of eyebrow and nose Nerve: Facial Action: Moves scalp; raises eyebrows; wrinkles forehead; "surprise"

Muscle: Posterior Trapezius

Origin: Occipital protuberance, nuchal ligament, spinous processes of C7-T12 Insertion: Clavicle acromion process, and scapular spine Nerve: Accessory (cranial nerve XI) Action: Extends and laterally flexes neck

Muscle: Oblique Inferior

Origin: Orbital plate of maxilla Insertion: Sclera of eye Nerve: Oculomotor Action: Elevates and laterally moves eye

Muscle: Hypothenar Muscles Abductor digiti minimi

Origin: Pisiform Insertion: Base of digit 5 Nerve: Ulnar Action: Abducts and flexes little finger

Muscle: Risorius

Origin: Platysma and masseter fascia Insertion: Orbicularis iris and skin at corner of mouth Nerve: Facial Action: Draws corner of mouth laterally; risor-laughter

Muscle: Soft Palate Uvalae

Origin: Posterior nasal spine Insertion: Uvula Nerve: Pharyngeal plexus Action: Elevates uvula

Muscle: Pelvic Diaphragm Levator ani

Origin: Posterior pubis and ischial spine Insertion: Sacrum and coccyx Nerve: Fourth sacral Action: Elevates anus; supports pelvic organs

Muscle: Cricoarytenoids Posterior

Origin: Posterior side of circoid cartilage Insertion: Thyroid cartilage Nerve: Recurrent laryngeal Action: Widens opening of larynx

Muscle: Posterior and Lateral Gluteus minimus

Origin: Posterior surface of ilium Insertion: Greater trochanter of femur Nerve: Superior gluteal Action: Abducts and medially rotates thigh; tilts pelvis toward supported side

Muscle: Posterior and Lateral Gluteus medius

Origin: Posterior surface of ilium Insertion: Greater trochanter of femur Nerve: Superior gluteal Action: Abducts and medially rotates thigh; tilts pelvis toward supported side.

Muscle: Posterior and Lateral Gluteus maximus

Origin: Posterior surface of ilium, sacrum, and coccyx Insertion: Gluteal tuberosity of femur and iliotibial tract Nerve: Inferior gluteal Action: Extends hip; abducts and laterally rotates thigh

Muscle: Posterior Forearm Abductor pollicis longus

Origin: Posterior ulna and radius and interosseous membrane Insertion: Base of first metacarpal bone Nerve: Radial Action: Abducts and extends thumb; abducts wrist

Muscle: Anterior Compartment Tibialis

Origin: Proximal, lateral tibia and interosseous membrane Insertion: Medial cuneiform and first metatarsal bone Nerve: Deep fibular Action: Dorsiflexes and inverts foot

Muscle Medial Compartment Pectineus

Origin: Pubic crest Insertion: Pectineal line of femur Nerve: Femoral and obturator Action: Adducts thigh; flexes hip

Muscle: Anterior Rectus abdominis

Origin: Pubic crest and symphysis pubis Insertion: Xiphoid process and inferior ribs Nerve: Branches of lower thoracic Action: Flexes vertebral column; compresses abdominal wall

Muscle: Perineum External urethral sphincter

Origin: Pubic ramus Insertion: Median raphe Nerve: Pudendal Action: Constricts urethra to stop urine flow

Muscle: Medial Compartment Adductor brevis

Origin: Pubis Insertion: Pectineal line and linea aspera of femur Nerve: Obturator Action: Adducts and laterally rotates thigh; flexes hip

Muscle: Medial Compartment Gracilis

Origin: Pubis near symphysis Insertion: Tibia Nerve: Obturator Action: Adducts thigh; flexes knee

Muscle: Anterior Forearm Flexor pollicis longus

Origin: Radius Insertion: Distal phalanx of thumb Nerve: Median Action: Flexes thumb

Muscle: Posterior Forearm Extensor pollicis brevis

Origin: Radius Insertion: Proximal phalanx of thumb Nerve: Radial Action: Extends and abducts thumb; abducts wrist

Muscle: Anterior Compartment Quadriceps femoris

Origin: Rectus femoris anterior iliac spine Vastus lateralis-greater trochanter and linea aspera of femur Vastus intermedius-body of femur Vastus medialis-linea aspera of femur Insertion: Patella and onto tibial tuberosity through patellar ligament Nerve: Femoral Action: Extends knee; rectus femoris also flexes hip

Muscle: Longissimus Thoracis

Origin: Ribs and lower thoracic vertebrae Insertion: Transverse processes of upper lumbar vertebrae and ribs Nerve: Dorsal rami of thoracic and lumbar nerves Action: Extends vertebral column

Muscle: Obturator Piriformis

Origin: Sacrum and ilium Insertion: Greater trochanter of femur Nerve: S1 and S2 Action: Laterally rotates and abducts thigh

Muscle: Superficial Erector spina divides into three columns Illiocostalis Lumborum

Origin: Sacrum, ilium, and lumbar vertebrae Insertion: Inferior six ribs Nerve: Dorsal rami of thoracic and lumbar nerves Action: Extends, laterally flexes, and rotates vertebral column

Muscles: Midpalmar Muscles Interossei Palmar

Origin: Second, fourth, and fifth metacarpal bones Insertion: Digits 2, 4, and 5 Nerve: Ulnar Action: Adducts second, fourth, and fifth digits

Muscle: Anterior Transversus abdominis

Origin: Seventh to twelfth costal cartilages, lumbar fascia, iliac crest, and inguinal ligament Insertion: Xiphoid process, linea alba, and pubic tubercle Nerve: Lower thoracic Action: Compresses abdominal wall

Muscle: Midpalmar Muscles Interossei Dorsal

Origin: Sides of metacarpal bones Insertion: Proximal phalanges of digits 2, 3, and 4 Nerve: Ulnar Action: Abducts second, third, and fourth digits

Muscle: Soft Palate Palatopharyngeus

Origin: Soft palate Insertion: Pharynx Nerve: Pharyngeal plexus Action: Narrows fauces; depresses palate; elevates pharynx

Muscle: Extrinsic Muscles: Palatoglossus

Origin: Soft palate Insertion: Tongue Nerve: Pharyngeal plexus Action: Elevates posterior tongue

Muscle: Soft Palate Palatoglossus

Origin: Soft palate Insertion: Tongue Nerve: Pharyngeal plexus Action: Narrows fauces; elevates posterior tongue.

Muscle: Soft Palate Tensor veli palatini

Origin: Sphenoid and auditory tube Insertion: Soft palate division of auditory tube Nerve: Mandibular division of trigeminal Action: Tenses soft palate; opens auditory tube

Muscle: Semispinalis Splenius cervics

Origin: Spinous processes of C3-C5 Insertion: Transverse processes of C1-C3 Nerve: Dorsal rami of cervical nerves Action: Rotates and extends neck

Muscle: Rhomboideus Major

Origin: Spinous processes of T1-T4 Insertion: Medial border of scapula Nerve: Dorsal scapular Action: Retracts, rotates and fixes scapula

Muscle: Latissimus dorsi

Origin: Spinous processes of T7-L5; sacrum and iliac crest; inferior angle of scapula in some people Insertion: Medial crest of intertubercular groove Nerve: Thoracodorsal Action: Adducts and medially rotates arm; extends shoulder

Muscle: Deep Interspinales

Origin: Spinous processes of all vertebrae Insertion: Next superior spinous process Nerve: Dorsal rami of spinal nerves Action: Extends back and neck

Muscle: Pharynx Pharyngeal constrictors Middle

Origin: Stylohyoid ligament and hyoid Insertion: Pharyngeal raphe Nerve: Pharyngeal plexus Action: Narrows pharynx in swallowing

Muscle: Suprahyoid Muscles Stylohyoid

Origin: Styloid process Insertion: Hyoid Nerve: Facial Action: Elevates hyoid

Muscle: Stylopharyngeus

Origin: Styloid process Insertion: Pharynx Nerve: Glossopharyngeus Action: Elevates pharynx

Muscle: Extrinsic Muscles Styloglossus

Origin: Styloid process of temporal bone Insertion: Tongue (lateral and inferior) Nerve: Hypoglossal Action: Retracts tongue

Muscle: Rotator cuff Subscapularis

Origin: Subscapular fossa Insertion: Lesser tubercle of humerus Nerve: Upper and lower sub scapular C5 and C6 Action: Medially rotates arm; holds head of humerus in place

Muscle: Infrahyoid Muscles Omohyoid

Origin: Superior border of scapula Insertion: Hyoid Nerve: Upper cervical through ansa cervicalis Action: Depresses hyoid; fixes hyoid when opening mouth

Muscle: Intercostals Internal

Origin: Superior margin of each rib Insertion: Inferior border of next rib above Nerve: Intercostal Action: Forced expiration depresses ribs

Muscle: Superficial Erector spina divides into three columns Illiocostalis Cervicis

Origin: Superior six ribs Insertion: Transverse processes of middle cervical vertebrae Nerve: Dorsal rami of thoracic nerves Action: Extends, laterally flexes, and rotates vertebral column

Muscle: Lateral Compartment Fibularis longus

Origin: Superior two-thirds of lateral fibula Insertion: First metatarsal bone and medial cuneiform Nerve: Superficial fibular Action: Everts and plantar flexes foot

Muscle: Rotator Cuff Supraspinatus

Origin: Supraspinous fossa Insertion: Greater tubercle of humerus Nerve: Suprascapular C5 and C6 Action: Abducts arm; holds head of humerus in place

Muscle: Spinalis Thoracis

Origin: T11-L2 Insertion: Spinous processes of middle and upper thoracic vertebrae Nerve: Dorsal rami of thoracic nerves Action: Extends vertebral column

Muscle: Deep Psoas minor

Origin: T12-L1 Insertion: Pectineal line near pubic crest Nerve: L1 Action: Flexes vertebral column

Muscle: Anterior Iliopsoas Psoas major

Origin: T12-L5 Insertion: Lesser trochanter of femur Nerve: Lumbar plexus Action: Flexes hip

Muscle: Soft Palate Levator veli palatini

Origin: Temporal bone and pharyngotympanic Insertion: Tongue Nerve: Pharyngeal plexus Action: Elevates soft palate during swallowing

Muscle: Temporalis

Origin: Temporal fossa Insertion: Anterior portion of mandibular ramus and coronoid process Nerve: Mandibular division of trigeminal Action: Elevates and retracts (move posteriorly) mandible; involved in excursion

Muscles: Lumbricales

Origin: Tendons of flexor digitorum longus Insertion: Extensor expansion of digits 2-5 Nerve: Lateral and medial plantar Action: Flex proximal and extend middle and distal phalanges

Muscles: Midpalmar Muscles Lumbricals

Origin: Tendons of flexor digitorum profundus Insertion: Digits 2-5 Nerve: Two on radial side--median; two on ulnar side--ulnar Action: Flexes proximal and extends middle and distal phalanges

Muscle: Thenar Muscles Adductor pollicis

Origin: Third metacarpal bone, second metacarpal bone, trapezoid, and capitate Insertion: Proximal phalanx of thumb Nerve: Ulnar Action: Adducts thumb

Pectoralis minor

Origin: Third to fifth ribs Insertion: Coracoid process of scapula Nerve: Medial pectoral Action: Depresses scapula or elevates ribs

Muscle: Plantar interossei

Origin: Third, fourth, and fifth metatarsal bones Insertion: Proximal phalanges of digits 3, 4, and 5 Nerve: Lateral plantar Action: Adduct third, fourth, and fifth toes

Muscle: Pharynx Pharyngeal constrictors Inferior

Origin: Thyroid and circoid cartilages Insertion: Pharyngeal raphe Nerve: Pharyngeal plexus Action: Narrows inferior portion of pharynx in swallowing

Muscle: Thyroarytenoid

Origin: Thyroid cartilage Insertion: Arytenoid cartilage Nerve: Recurrent laryngeal Action: Shortens (relaxes) vocal cords

Muscle: Vocalis

Origin: Thyroid cartilage Insertion: Arytenoid cartilage Nerve: Recurrent laryngeal Action: Shortens (relaxes) vocal cords

Muscle: Infrahyoid Muscles Thyrohyoid

Origin: Thyroid cartilage Insertion: Hyoid Nerve: Upper cervical, passage with hypoglossal Action: Depresses hyoid and elevates thyroid cartilage of larynx; fixes hyoid when opening mouth

Muscle: Posterior Compartment Deep Flexor digitorum longus

Origin: Tibia Insertion: Four tendons to distal phalanges of four lateral toes Nerve: Tibial Action: Flexes four lateral toes; plantar flexes and inverts foot

Muscle: Posterior Compartment Tibialis posterior

Origin: Tibia, interosseous membrane, and fibula Insertion: Navicular cuneiforms, cuboid, and second through court metatarsal bones Nerve: Tibial Action: Plantar flexes and inverts foot

Muscle: Levator scapulae

Origin: Transverse processes of C1-C4 Insertion: Superior angle of scapula Nerve: Dorsal scapular Action: Elevates, retracts, and rotates scapula; laterally flexes neck

Muscle: Scalene Muscles Anterior

Origin: Transverse processes of C3-C6 Insertion: First rib Nerve: Cervical plexus Action: Elevates first rib

Muscle: Scalene Muscles Posterior

Origin: Transverse processes of C4-C6 Insertion: Second rib Nerve: Cervical and brachial plexuses Action: Elevates second rib

Muscle: Semispinalis Cervicis

Origin: Transverse processes of T2-T5 Insertion: Spinous processes of C2-C5 Nerve: Dorsal rami of cervical nerves Action: Extends neck

Muscle: Semispinalis Thoracis

Origin: Transverse processes of T5-T11 Insertion: Spinous processes of C5-T4 Nerve: Dorsal rami of thoracic nerves Action: Extends vertebral column

Muscle: Deep Rotatores

Origin: Transverse processes of all vertebrae Insertion: Base of spinous process of superior vertebrae Nerve: Dorsal rami of spinal nerves Action: Extends and rotates vertebral column

Muscle: Deep Intertransversarii

Origin: Transverse processes of all vertebrae Insertion: Next superior transverse process Nerve: Dorsal rami of spinal nerves Action: Laterally flexes vertebral column

Muscle: Deep Multifidus

Origin: Transverse processes of vertebrae; posterior surface of sacrum and ilium Insertion: Spinous processes of superior vertebrae Nerve: Dorsal rami of spinal nerves Action: Extends and rotates vertebral column

Muscle: Thenar Muscles Opponens pollicis

Origin: Trapezium and flexor retinaculum Insertion: First metacarpal bone Nerve: Median Action: Opposes thumb

Muscle: Anterior Forearm Flexor digitorum profundus

Origin: Ulna Insertion: Distal phalanges of digits 2-5 Nerve: Ulnar and median Action: Flexes fingers at metacarpophalangeal joints and interphalangeal joints and wrist

Muscle: Posterior Forearm Extensor pollicis longus

Origin: Ulna Insertion: Distal phalanx of thumb Nerve: Radial Action: Extends thumb

Muscle: Posterior Forearm Extensor incidis

Origin: Ulna Insertion: Extensor tendon expansion over digit 2 Nerve: Radial Action: Extends forefinger and wrist

Muscle: Posterior Longissimus capitis

Origin: Upper thoracic and lower cervical vertebrae Insertion: Mastoid process Nerve: Dorsal rami fo cervical nerves Action: Extends, rotates, and laterally flexes neck

Muscle: Longissimus Capitis

Origin: Upper thoracic and lower cervical vertebrae Insertion: Mastoid process Nerve: Dorsal rami of cervical nerves Action: Extends head

Muscle: Longissimus Cervicis

Origin: Upper thoracic vertebrae Insertion: Transverse processes of upper cervical vertebrae Nerve: Dorsal rami of cervical nerves Action: Extends neck

Muscle: Intrinsic Muscles Longitudinal, transverse, and vertical (not illustrated)

Origin: Within tongue Insertion: Within tongue Nerve: Hypoglossal Action: Change tongue shape

Muscle: Masseter

Origin: Zygomatic arch Insertion: Lateral side of mandibular ramus Nerve: Mandibular division of trigeminal Action: Elevates and protracts (move anteriorly) mandible; involved in excursion

Muscle: Zygomaticus major

Origin: Zygomatic bone Insertion: Angle of mouth Nerve: Facial Action: Elevates and abducts upper lip and corner of mouth; "smile"

Muscle: Zygomaticus minor

Origin: Zygomatic bone Insertion: Orbicularis oris of upper lip Nerve: Facial Action: Elevates and abducts upper lip: "smile"

What are parallel muscles?

Parallel muscles, similarly to convergent muscles, have fascicles that are organized parallel to the long axis of the muscle, but they terminate on a flat tendon that spans the width of the entire muscle. As a consequence, parallel muscles can shorten to a large degree because the fascicles are in a direct line with the tendon; however, they contract with less force because fewer total fascicles are attached to the tendon. In addition to those shown in table 10.1, the hyoid muscles in the neck are examples of parallel muscles.

Summary of Muscle Actions on the Shoulder and Arm Adduction:

Pectoralis major Latissimus dorsi Teres major Teres minor Triceps brachii Coracobrachialis

Summary of Muscle Actions on the Shoulder and Arm Medial Rotation:

Pectoralis major Teres major Latissimus dorsi Deltoid Subscapularis

What are pennate muscles?

Pennate muscles have fascicles that emerge like the barbs on a feather from a common tendon that runs the length of the entire muscle. The location of the fascicles relative to the tendon is the basis for different types of pennate muscles.

What muscles are used to cause lateral and medial excursion of the jaw?

Pterygoids

Name the muscles responsible for opening and closing the jaw.

Pterygoids Masseter Temporalis

Function

Recall from chapter 8 that body movements have names, for example abduction and adduction. Abductors and adductors are the muscles that cause that type of movement. Abduction moves a structure away from the midline, and adduction moves a structure toward the midline.

What makes learning the names of muscles much easier?

Recognizing the Greek or Latin origins of muscle names makes learning those names much easier. In the following list, translations of the muscle names are given in parentheses.

FIGURE 10.11 Tongue Muscles

Right lateral view of tongue muscles. (Muscle names in bold are tongue muscles.)

Rotation and lateral flexion of the neck are accomplished by what muscles?

Rotation and lateral flexion of the neck are accomplished by muscles of both the lateral and posterior groups.

Name the major movements of the head caused by contraction of the anterior, posterior, and lateral neck muscles.

Rotation and lateral flexion of the neck are accomplished by muscles of both the lateral and posterior groups. The sternocleidomastoid muscle is the prime mover of the lateral group. It is easily seen on the anterior and lateral sides of the neck, especially if the head is extended slightly and rotated to one side. If the sternocleidomastoid muscle on only one side of the neck contracts, the neck is rotated toward the opposite side. If both contract together, they flex the neck (chin to chest). The scalene muscles, which are deep and lateral on the neck, assist the sternocleidomastoid in neck flexion. Lateral flexion of the neck (moving the head back to the midline after it has been tilted to one side) is accomplished by the lateral flexors of the opposite side.

What are the groups of muscles that originate on the hip bone?

Several hip muscles originate on the hip bone and insert onto the femur. These muscles are divided into three groups: anterior, posterolateral, and deep.

What does slight mandibular depression involve?

Slight mandibular depression involves relaxation of the mandibular elevators and the pull of gravity.

What does the zygomaticus major, minor, the levator anguli iris, and the risorius do?

Smiling is accomplished by the zygomaticus major, and minor, the levator anguli iris, and the risorius.

How is sneering accomplished?

Sneering is accomplished by the levator labii superioris.

Give an example of how all muscles are not attached to bone at both ends.

Some facial muscles attach to the skin, moving it as the muscles contract. One such movement is easily recognized as a smile.

What do tendinous intersections trasect to?

Tendinous intersections transect the rectus abdominis at three, or sometimes more, locations, causing the abdominal wall of a lean, well-muscles person to appear segmented (a "six-pack").

Summary of Muscle Actions on the Hip and Thigh Medial Rotation

Tensor fascia latae Gluteus medius Gluteus minimus

Which muscles open and close the openings to the auditory tube and to the larynx?

Tensor veli palatini Salpingopharyngeus The salpingopharyngeus also opens the auditory tube, which connects the middle ear to the pharynx. Opening the auditory tube equalizes the pressure between the middle ear and the atmosphere; this is why It is sometimes helpful to chew gum or swallow when ascending or descending a mountain in a car or when changing altitudes in an airplane.

Explain the anatomical basis for the segments ("cuts") seen on a well-muscled individual's abdomen. What are the functions of the abdominal muscles?List the muscles of the anterior abdominal wall.

The abdominal muscle help rotate the vertebral column. The muscles of the anterior abdominal wall include the (1) rectus abdominis, (2) external abdominal oblique, (3) internal abdominal oblique, and (4) transversus abdominis. These muscles flex and rotate the vertebral column. Contraction of the abdominal muscles when the vertebral column is stationary decreases the volume of the abdominal cavity and the thoracic cavity is stationary decreases the volume of the abdominal cavity and the thoracic cavity and can aid in such functions as forced expiration, vomitting, defecation, coughing, and childbirth. The criss-cross layering of all the abdominal muscles creates a strong anterior wall, which holds in and protects the abdominal viscera. This is especially important because the anterior wall is not supported by bone. In a relatively muscular person with little body fat, a vertical line called the linea alba, or white line, is visible. It is an area consisting of only dense regular connective tissue. The linea alba extends from the diploid process of the sternum through the navel to the pubis. On each side of the linea alba is the recuts abdominis, surrounded by a rectus sheath. Tendinous intersections (tendinous inscriptions) transect the rectus abdominis at three, or sometimes more, locations, causing the abdominal wall of a lean, well-muscled person to appear segmented (a "six-pack"). Lateral to the rectus abdominis is the linea semilunaris (a crescent- or half-moon-shaped line); lateral to it are three layers of muscle. From superficial (outermost) to deep (innermost), these muscles are the external abdominal oblique, internal abdominal oblique, and transversus abdominis.

A tennis player complains of pain in the shoulder when she abducts her arm while serving or reaching for an overhead volley (extreme abduction). In extreme abduction, the supraspinatus muscle rises superiorly and may be damaged by compression against what bony structure?

The acromion process, the coracoid process and lesser tubercle.

What are the anterior and posterior halves of the perineum called?

The anterior half of the perineum is the urogenital triangle, and the posterior half of the perineum is the anal triangle.

What muscles flex the hip?

The anterior hip muscles, the iliacus and the psoas major, flex the hip.

What is the iliopsoas?

Name the anterior hip muscle that flexes the hip. What muscles act as synergists to this muscle?

The anterior hip muscles, the iliacus and the psoas major, flex the hip. Because these muscles share an insertion and produce the same movement, they are often referred to collectively as the iliopsoas. When the thigh is fixed, the iliopsoas flexes the trunk on the thigh. For example, the iliopsoas does most of the work when a person does sit-ups.

What are the extensor muscles of the leg?

The anterior leg muscles are extensor muscles. They cause dorsiflexion, eversion, and inversion of the foot as well as extension of the toes.

What are the anterior thigh muscles?

The anterior thigh muscles are the quadriceps femurs and the sartorial.

FIGURE 10.32 Cross Section Through the Left Leg

The anterior, posterior, and lateral compartments are labeled.

Which muscles are responsible for moving the ears, the eyebrows, the eyelids, and the nose?

The auricular anterior, which draws the ear up and forward; the auricular superior, which raises it; and the auricular posterior, which pulls it backwards The occipitalfrontalis raises the eyebrows and furrows the skin of the forehead. The orbicularis oculi closes the eyelids and causes "crow's-feet" wrinkles in the skin at the lateral corners of the eyes. The levator palpebrae superioris raises the upper lids. The corrugated supercilii draws the eyebrows inferiorly and medially, producing vertical corrugations (furrows) in the skin between the eyes. The nasals dilates the nostrils.

What assist the brachial in elbow flexion?

The biceps brachii and the brachioradialis muscles assist the brachial in elbow flexion.

Is the biceps brachii readily visible?

The biceps brachii is readily visible on the anterior aspect of the arm.

Give an example of fusiform muscle.

The biceps brachii, which flexes the forearm, is one example of a fusiform muscle.

Where does the brachialis lie deep to?

The brachialis lies deep to the biceps brachii and can be seen only as a mass on the medial and lateral sides of the arm.

What does the brachioradialis form?

The brachioradialis forms a bulge on the anterolateral side of the forearm just distal to the elbow. If the elbow is forcefully flexed in the mid-tone position (midway between pronation and supination), the brachioradials stands out clearly on the forearm.

What does the corrugator supercilii do?

The corrugator supercilii draws the eyebrows inferiorly and medially, producing vertical corrugations (furrow) in the skin between the eyes.

What creates a strong anterior wall?

The criss-cross layering of all the abdominal muscles creates a strong anterior wall, which holds in and protects the abdominal viscera. This is especially important because the anterior wall is not supported by bone.

What muscles laterally rotate the thigh?

The deep hip muscles, as well as the gluteus Maximus, laterally rotate the thigh.

Shape

The deltoid (triangular) muscle is triangular in shape, a Quadratus (quadrate) muscle is rectangular, and a teres (round) muscle is round.

Describe the deltoid muscle.

The deltoid muscle is like three muscles in one: The anterior fibers flex the shoulder, the lateral fibers abduct the arm, and the posterior fibers extend the shoulder. The deltoid muscle is part of the group of muscles that binds the humerus to the scapula. However, the primary muscles holding the head of the humerus in the glenoid cavity are called the rotator cuff muscles because they form a cuff or cap over the proximal humerus.

While weight training, Pedro strained his back injuring the following muscles: psoas major, iliac, pectinous, sartorial, vastus lateralis, vastus medium, vastus intermedium, and rectus femoris. Predict Pedro's symptoms and which movements of his lower limb were affected, other than walking on a flat surface. What types of daily tasks would be difficult for Pedro to perform?

The description of Pedro's injury provided specific information about the regions of the body affected: the left hip and thigh. These facts will help us determine Pedro's symptoms and predict the movements that may be affected by his injury. We read in this chapter that the muscles affected by Pedro's injury (poses major, iliac, pectinous, sartorial, vastus laterals, vastus medius, vasuts intermedius, and rectus femoris) are involved in flexing the hip, the knee, or both. Therefore, we can conclude that movements involving hip and knee flexion, such as walking up and down stairs, would be affected. Any tasks that require Pedro to walk up and down the stairs would be more difficult for him. Sitting and standing may also be affected, but the weakness in Pedro's left hip and thigh may be compensated for by increased muscle strength on his right side.

What is the diaphragm responsible for?

The diaphragm is the muscle responsible for normal, quiet breathing. It is a dome-shaped muscle; when it contracts, the dome flattens slightly, causing the volume of the thoracic cavity to increase and resulting in inspiration.

List the actions of the group of back muscles that attaches to the vertebrae or ribs (or both). What is the name of the superficial subgroup?

The erector spinae group of muscles on each side of the back consists of three subgroups: (1) the ilicostalis, (2) the longissimus and (3) the spinals. The erector spinae is the superficial group. Iliocostalis -Cervicis- Extends laterally flexes, and rotates vertebral column -Thoracis- Extends laterally flexes, and rotates vertebral column -Lumborum- Extends, laterally flexes, and rotates vertebral column Longissimus Capitis- Extends head Cervicis- Extends neck Thoracis- Extends vertebral column Spinalis -Cervicis- Extends neck -Thoracis- Extends vertebral column

What do the external intercostals do?

The external intercostals elevate the ribs during quiet, resting inspiration.

Contrast the location and actions of the extrinsic and intrinsic muscles. What is the retinaculum?

The extrinsic hand muscles are located in the posterior forearm and have tendons that extend into the hand. These muscle extend the wrist and fingers. A strong ring of fibrous connective tissue, the extensor retinaculum, encircles the flexor and extensor tendons to hold them in place around the wrist, so that they do not "bowstring" (pull away from the bone) during muscle contraction. The intrinsic hand muscles are entirely within the hand. These muscles move the fingers. Abduction of the fingers is accomplished by the dorsal interossei and the abductor digiti minimi, whereas adduction is a function of the palmar interossei. A retinaculum is a band of thickened deep fascia around tendons that holds them in place. It is not part of any muscle. Its function is mostly to stabilize a tendon. The term retinaculum is New Latin, derived from the Latin ver retinere.

Where are the extrinsic hand muscles located?

The extrinsic hand muscles are located in the posterior forearm and have tendons that extend into the hand. These muscles extend the wrist and fingers.

What are the extrinsic muscles named for?

The extrinsic muscles are name for their origin and insertion.

Describe the fascicles of the trapezius muscles.

The fascicles of the trapezius muscles are shorter at the base of the neck and leave a diamond-shaped area over the inferior cervical and superior thoracic vertebral spines.

Where does the fibularis brevis insert onto?

The fibularis brevis inserts onto the fifth metatarsal bone and everts and plantar flexes the foot.

Where does the fibulas longus cross under?

The fibularis longus crosses under the lateral four metatarsal bones to insert onto the first metatarsal bone and medial cuneiform.

What are the five classes of muscle shape?

The five classes are circular, convergent, parallel, pennate, and fusiform. Within some of the classes, there patterns based on the shape of the particular muscle, including triangular, trapezium, rhomboidal, and quadrate.

How are the forearm muscles divided?

The forearm muscles are divided into anterior and posterior groups.

Class I

The fulcrum (F) is located between the weight (W) and the pull (P), or force. The pull is directed downward, and the weight, on the opposite side of the fulcrum, is lifted. In the body, the fulcrum extends through several cervical vertebrae.

Size

The gluteus Maximus (large) is the largest muscle of the buttock, and the gluteus minus (small) is the smallest. A longus (long) muscle is longer than a brevis (short) muscle. In addition, a second part to the name immediately tells us there is more than one related muscle. For example, if there is a brevis muscle, most likely a longus muscle is present in the same area.

What does the gluteus Maximus contribute?

The gluteus Maximus contributes most of the mass that can be seen as the buttocks.

When does the gluteus Maximus function at its maximum force?

The gluteus Maximus functions at its maximum force in extension of the thigh when the hip is flexed at a 45-degree angle, so that the muscle is optimally stretched, which accounts for both the spinter's stance and the bicycle racing posture.

What muscles help tilt the pelvis and maintain the trunk in an upright posture?

The gluteus medius and minimus muscles help tilt the pelvis and maintain the trunk in an upright posture during walking, as the foot of the opposite limb is raised from the ground. Without the action of these muscles, the pelvis tends to sag downward on the unsupported side.

What is the gluteus medius?

The gluteus medius, a common site for injections, creates a smaller mass just superior and lateral to the gluteus Maximus.

What muscle rotate the hip?

The gluteus medius, gluteus minimus, and tensor fasciae late medially rotate the hip.

What is the hinge called?

The hinge is called a fulcrum (F).

How are the hyoid muscles divided?

The hyoid muscles are divided into a suprahyoid group superior to the hyoid bone and an infra hyoid group inferior to it.

Explain the interaction of the suprahyoid and infrahyoid muscles in swallowing.

The hyoid muscles are divided into a suprahyoid group superior to the hyoid bone and an infrahyoid group inferior to it. When the hyoid bone is fixed by the infrahyoid muscles so that the bone is stabilized from below, the suprahyoid muscles can help depress the mandible. If the suprahyoid muscles fix the hyoid and thus stabilize it from above, the thyroid muscle (an infrahyoid muscle) can elevate the larynx.

What is the hypothenar eminence?

The hypothenar eminence on the ulnar side of the hand is formed by (1) the abductor digit minimi, (2) the flexor digiti minimi brevis, and (3) the opponens digiti minimi.

What is the extensor indicis?

The index finger also has an additional extensor, the extensor indicis.

What is the insertion?

The insertion, or mobile end, is usually the distal end of the muscle attached to the bone being pulled toward the other bone of the joint.

What do the internal intercostals and transverse thoracic do?

The internal intercostals and transverses thoracis muscles depress the ribs during forced expiration.

Where are the intrinsic hand muscles?

The intrinsic hand muscles are entirely within the hand. These muscles move the fingers.

What are the intrinsic muscles named for?

The intrinsic muscles are name for their fascicle orientation in the tongue.

What do the lateral leg muscles do?

The lateral leg muscles primarily evert the foot, but they also help plantar flex the foot.

What does the levator palpebrae superioris do?

The levator palpebrae superioris raises the upper lids. A droopy eyelid on one side, called ptosis, usually indicates that the nerve to the elevator palpebrae superioris, or the part of the brain controlling the nerve, has been damaged.

Where does the lever move?

The lever moves at the hinge and can apply force to a weight (W).

What is the extensor digiti minimi

The little finger has an additional extensor, the extensor digiti minimi.

Describe pennate muscles.

The long tendons of pennate muscles can extend for some distance between a muscle belly and its insertion. The pennate arrangement allows a large number of fascicles to attach to a single tendon, with the force of contraction concentrated at the tendon. The muscles that extend the knee, as well s the deltoid muscle as shown in table 10.1 are multipennate muscles.

FIGURE 10.30 Right Medial Thigh Muscles

The medial thigh muscles adduct the thigh. (Muscle names are in bold.)

What are the medial thigh muscles involved in?

The medial thigh muscles are involved primarily in adduction of the thigh. Some of these muscles also laterally rotate the thigh and/or flex or extend the hip. The gracilis also flexes the knee.

What are the muscles of elbow extension?

The muscles of elbow extension are the triceps brachii and the anconeus muscles.

What are some of the strongest muscles in the body?

The muscles of mastication are some of the strongest muscles of the body; they bring the mandibular teeth forcefully against the maxillary teeth to crush food.

What do the muscles of mastication include?

The muscles of mastication include (1) the temporalis, (2) the masseter, and (3) the pterygoids.

What muscle rotate the vertebral column?

The muscles of the anterior wall include the (1) rectus abdomens, (2) external abdominal oblique, (3) internal abdominal oblique, and (4) transverses abdomens. These muscles flex and rotate the vertebral column.

Where are the muscles of the leg that move the ankle and the foot?

The muscles of the leg that move the ankle and the foot are located in the leg and have tendons that extend into the foot similarly to the extrinsic hand muscles.

FIGURE 10.16 Muscles of the Thorax

The muscles of the thorax are important for respiration. (Muscle names are in bold.)

What are the thorax muscles involved in?

The muscles of the thorax are mainly involved in the control of breathing.

What do the muscles of the upper limb include?

The muscles of the upper limb include those that move the scapula and those that move the arm, forearm, and hand.

Name the seven muscles that attach the scapula to the thorax. What muscles attach the arm to the thorax?

The muscles that attach the scapula to the thorax include (1) trapezius, (2) elevator scapulae (3) rhomboideus major and (4) rhomboideus minor, (5) serrates anterior, and (6) pectoralis minor. These muscles move the scapula, permitting a wide range of movements of the upper limb, or they act as fixators to hold the scapula firmly in position when the arm muscles contract. Each of our arms is attached to the thorax by several muscles, including the pectoralis major and the latissimus dorsi. Notice that the pectoralis major is listed in 10.14 as both a flexor and an extensor. This muscle flexes the extended shoulder and extends the flexed shoulder. Try these movement and notice the position and acton of the muscle. The deltoid muscle is also listed in table 10.14 as a flexor and an extensor. The deltoid muscle is like three muscles in one: The anterior fibers flex the shoulder, the lateral fibers abduct the arm, and the posterior fibers extend the shoulder. The deltoid muscle is part of the group of muscles that binds the humerus to the scapula. However, the primary muscles holding the head of the humerus in the glenoid cavity are called the rotator cuff muscles because they form a cuff or cap over the proximal humerus.

What are the muscles that attach to scapula include?

The muscles that attach to the scapula include the (1) trapezius, (2) levator scapulae, (3) rhomboideus major and (4) rhomboideus minor, (5) serratus anterior, and (6) pectoralis minor. These muscles move the scapula, permitting a wide range of movements of the upper limb, or they act as fyxators to hold the scapula firmly in position when the arm muscles contract.

Explain what muscles rotate the vertebral column.

The muscles that extend, laterally flex, and rotate the vertebral column are divided into superficial and deep groups. In general, the muscles of the superificial group connect the vertebrae to the ribs, whereas the muscles of the deep group connect vertebrate together.

What are the muscles that pronate the forearm and hand?

The muscles that pronate (turn palm down) the forearm and hand are (1) the pronator quadratus and (2) the pronator teres.

What muscles supinate the forearm and hand?

The muscles that supinate (turn palm up) the forearm and hand are (1) the supinator and (2) the biceps brachii.

What muscles produce supination and pronation of the forearm? Where are these muscles located?

The muscles that supinate (turn palm up) the forearm and hand are (1) the supinator and (2) the biceps brachii. The muscles that pronate (turn palm down) the forearm and hand are (1) the pronator quadrates and (2) the pronator teres. Supinator Lateral posterior elbow Biceps brachii Anterior arm Pronator quadratus Anterior inferior to pronator teres Pronator teres Superior and anterior to pronator quadratus

What is the muscular ridge seen superficially in the posterior part of the neck and lateral midline composed of?

The muscular ridge seen superficially in the posterior part of the neck and lateral to the midline is composed of the trapezius muscle overlying the splenius capitis.

What is the name of a muscle based on?

The name of a specific muscle is based on at least seven characteristics, which are detailed in the following list.

Where do the oblique muscles insert onto?

The oblique (at an angle) muscles insert onto the posterolateral margin of the eyeball, so that both muscles laterally deviate the gaze as they contract. (1) The superior oblique elevates the posterior part of the eye, thus directing the pupil inferiorly and depressing the gaze. (2) The inferior oblique elevates the gaze.

What does the occipitofrontalis do?

The occipitofrontalis raises the eyebrows and furrows the skin of the forehead.

What does the orbiculares oculi do?

The orbiculares oculi closes the eyelids and causes "crow's feet" wrinkles in the skin at the lateral corners of the eyes .

What does the orbicularis oris and the buccinator do?

The orbicularis oris and buccinator, the kissing muscles, pucker the mouth.

What is the origin?

The origin, also called the fixed end, is usually the most stationary, proximal end of the muscle. Some muscles have more than one origin.

What is the belly?

The part of the muscle between the origin and the insertion is the belly.

What is the patellar ligament?

The patellar ligament is an extension of the patellar tendon onto the tibial tuberosity. The patellar ligament is the point that is tapped with a rubber hammer when eating the knee-jerk reflex in a physical examination.

What is the pelvic floor called?

The pelvic floor is called the pelvic diaphragm. It consists of the coccyges muscle and the levator ani muscle.

What is the pelvis?

The pelvis is a ring of bone with an inferior opening that is closed by a muscular wall, through which the anus and the urogenital openings penetrate.

What openings penetrate the pelvic diaphragm muscles? Name the area inferior to the pelvic diaphragm.

The pelvis is a ring of bone with an inferior opening that is closed by a muscular wall, through which the anus and the urogenital openings penetrate. The pelvic floor is called the pelvic diaphragm. It consists of the coccyges muscle and the levator ani muscle. Just inferior to the pelvic diaphragm is a diamond-shaped area called the perineum.

What are the hamstring muscles?

The posterior thigh muscles, collectively called the hamstring muscles, consist of the biceps femoris, the semimembranosus, and the semitendinosus. Their tendons are easily seen or felt on the medial and lateral posterior aspect of a slight bent knee.

What does the posterolateral hip muscles consist of?

The posterolateral hip muscles consist of the gluteal muscles and the tensor fascia latae.

What is the prime mover of elbow flexion?

The prime mover of elbow flexion is the brachial muscles.

Class III

The pull (P), or force, is located between the fulcrum (F) and the weight (W). The upward pull lifts the weight.

What do the quadriceps femoris have?

The quadriceps femoris have a common insertion, the patellar tendon, on and around the patella.

How many muscles is the quadriceps femoris?

The quadriceps femoris is actually four muscles: (1) the rectus femoris, (2) the vastus laterals, (3) the vastus medals, and (4) the vastus intermeidus. The quadriceps group extends the knee.

What does the quadriceps femoris make up?

The quadriceps femoris makes up the large mass on the anterior thigh.

What does the rectus femoris do?

The rectus femoris also flexes the hip because it crosses both the hip and knee joints.

Strabismus is a condition in which one or both eyes deviate in a medial or lateral direction. In some cases, strabismus is caused by a weakness in either the medial or the lateral rectus muscle. If the lateral rectus of the right eye is weak, in which direction does the eye deviate?

The right eye will deviate to the right and the left eye will deviate to the left.

What do the rotator cuff muscles include?

List the muscles forming the rotator cuff, and describe their function.

The rotator cuff muscles include (1) the infraspinatus, (2) the subscapularis, (3) the supraspinatus, and (4) the teres minor. A rotator cuff injury involves damage to one or more of these muscles or their tendons, usually the supraspinatus muscle. The muscles moving the arm are involved in flexion, extension, abduction, adduction, rotation, and circumduction. Infraspinatus- Laterally rotates arm; holds head of humerus in place Scapularis: Medially rotates arm; holds head of humerus in place Supraspinatus: Abducts arm; holds head of humerus in place Teres minor: Laterally rotates and adducts arm; holds head of humerus in place.

What does the salpingopharyngeus do?

The salpingopharyngeus also opens the auditory tube, which connects the middle ear to the pharynx. Opening the auditory tube equalizes the pressure between the middle ear and the atmosphere; this is why it is sometimes helpful to chew gum or swallow when ascending or descending a mountain in a car or when changing altitudes in an airplane.

What is the sartorius?

The sartorius is the longest muscle of the body, crossing from the lateral side of the hip to the medial side of the knee. As the muscle contracts, it flexes the hip and knee and laterally rotates the thigh. This is the action required for crossing the legs.

What do the scalene muscles do?

The scalene muscles elevate the first two ribs during more forceful inspiration.

What muscles assist the sternocleidomastoid in neck flexion?

The scalene muscles, which are deep and lateral on the neck, assist the sternocleidomastoid in neck flexion.

Where does the serrates anterior insert onto?

The serrauts anterior inserts onto the medial border of the scapula.

What greatly influences the degree to which a muscle can contract or the amount of force it can generate?

The shape and size of any given muscle greatly influence the degree to which it can contract and the amount of force it can generate.

What determines the type of movement for a muscle?

The shape of the muscle determines the type of movement it has.

What are the skeletal muscles of the face?

The skeletal muscles of the face are cutaneous muscles attached to the skin. Many animals have cutaneous muscles over the trunk that allow the skin to twitch to remove irritants, such as insects. In humans, facial expressions are important components of nonverbal communication, and the cutaneous muscles are confined primarily to the face and neck.

What does the soft palate, pharynx (throat), and larynx contain?

The soft palate, pharynx (throat), and larynx contain several muscles involved in swallowing and speech. The muscles of the soft palate close the posterior opening to the nasal cavity during swallowing.

What is muscle action?

The specific body movement a muscle contraction causes is called the muscle's action.

Describe the roles of the following in muscle action: agonist, antagonist, synergist, fixator, and prime mover.

The specific body movement a muscle contraction causes is called the muscle's action. Muscles are typically studied in groups called agonsits and antagonists. The action of a single muscle or group of muscles (agonist) is opposed by that of another muscle or group of muscles (antagonist). For example, the biceps brachii flexes (bends) the elbow, and the triceps brachii extends the elbow. In the example of elbow flexion, the biceps brachii is the agonist (flexes), whereas the triceps brachii is the antagonist (extends). When extending the elbow, the muscles' roles are reversed; the triceps brachii is the agonist and the biceps brachii is the antagonist. Most joins in the body have agonist and antagonist groups or pairs. Muscles also tend to function in groups to accomplish specific movements. The muscles of the group are called synergists. For example, the deltoid, biceps brachii, and pectorals major all help flex the shoulder. Furthermore, many muscles are members of more than one group, depending on the type of movement being produced. For example, the anterior part of the deltoid muscle functions with the flexors of the shoulder, whereas the posterior part functions with the extensors of the shoulder. In elbow flexion, the biceps brachii and the brachial are synergists. However, the brachial muscle is more important for elbow flexion than the biceps brachii. In a group of synergists, the muscle that contributes most of to the movement is called the prime mover. The brachial is the prime mover in elbow flexion. In some groups of synergists, the prime mover needs to be stabilized. The stabilizers of prime movers are called fixators. Usually, a fixator holds one bone in place relative to the body while a more distal bone is moved. For example, the origin of a prime mover is often stabilized by fixators, so that its action occurs at its point of insertion. When moving the humerus, the muscles of the scapula act as fixators to hold the scapular in place.

Origin and insertion.

The sternocleidomastoid has its origin on the sternum and clavicle and its insertion on the mastoid process of the temporal bone. The brachioradialis originates in the arm (brachium) and inserts on the radius.

What is the sternocleidomastoid muscle?

The sternocleidomastoid muscle is the prime mover of the lateral group. It is easily seen on the anterior and lateral sides of the neck, especially if the head is extended slightly and rotated on one side.

What muscles form the bulge of the calf?

The superficial muscles of the posterior compartment of the leg, the gastrocnemius and the soles, form the bulge of the calf. They merge with the small plantaris muscle to form the common calcaneal tendon, or Achilles tendon.

Can the superficial muscles that act on the scapula be seen?

The superficial muscles that act on the scapula can easily be seen on a living person. The trapezius forms the upper line from each shoulder to the neck, and the origin of the serrates anterior from the first eight or nine ribs can be seen along the lateral thorax.

Are the superior and inferior rectus straight?

The superior rectus and inferior rectus are not completely straight in their orientation to the eye; thus, they also medially deviate the gaze as they contract.

FIGURE 10.8 Facial Expressions

The surface anatomy of the muscles of facial expressions are shown in this figure.

What does the tendon of the flexor carpi radialis serve as?

The tendon of the flexor carpi radialis serves as a landmark for locating the radial pulse, which is lateral to the tendon.

Where can the tendons of the fibularis muscles be seen?

The tendons of the fibularis muscles can be seen on the lateral side of the ankle.

What is the thenar eminence?

The thenar eminence is a fleshy prominence at the base of the thumb formed by three muscles, which include (1) flexor policis brevis, (2) the abductor policis brevis, and (3) the opponens policis.

What does the tongue consist of?

The tongue consists of a mass of intrinsic muscles, which are found entirely within the tongue, and are involved in changing the shape of the tongue, and extrinsic muscles, which are outside of the tongue but attached to it, and help change the shape of and move th tongue.

In what ways are the tongue important to mastication and speech?

The tongue is important in mastication and speech in several ways: (1) It moves food around in the mouth; (2) with the buccinator, it holds food inlace while the teeth grind it; (3) it pushes food up to the palate and back toward the pharynx to initiate swallowing; and (4) it changes shape to modify sound during speech.

What does the triceps brachii constitute?

The triceps brachii constitutes the main mass visible on the posterior aspect of the arm.

What are the two points of attachment called?

The two points of attachment of each muscle to the bone are called the origin and the insertion.

Distinguish between the origin and the insertion of a muscle. In which direction is movement?

The two points of attachment of each muscle to the bone are called the origin and the insertion. The origin, also called the fixed end, is usually the most stationary, proximal end of the muscle. Some muscles have more than one origin. For example, the triceps brachii has three origins that join together to form one muscle. In the case of multiple origins, each origin is called a head. The insertion, or mobile end, is usually the distal end of the muscle attached to the bone being pulled toward the other bone of the joint. The part of the muscle between the origin and the insertion is the belly. At the attachment point, tendons connect each muscle to the bone. Tendons are composed of dense connective tissue and can be long and ropelike, broad and sheetlike, or very short. The specific body movement a muscle contraction causes is called the muscle's action. Muscles are typically studied in groups called agonist and antagonists. The action of a single muscle or group of muscles (agonist) is opposed by that of another muscle or group of muscles (antagonist). For example, the biceps brachii flexes (bends) the elbow, and the triceps brachii extends the elbow. In the example of elbow flexion, the biceps brachii is the agonist (flexes), whereas the triceps brachii is the antagonist (extends). When extending the elbow, the muscles' roles are reversed; the triceps brachii is the agonist and the biceps brachii is the antagonist. Most joints in the body have agonist and antagonist groups or pairs.

What is the vastus lateralis used for?

The vastus laterals is sometimes used as an injection site, especially in infants who do not have well-developed deltoid or gluteal muscles.

Class II

The weight (W) is located between the fulcrum (F) and the pull (P), or force. The upward pull lifts the weight. The movement of the mandible easier to compare to a wheelbarrow if the head is considered upside down.

Where are the wrist flexors and extensors visible?

The wrist flexors and extensors are visible on the anterior and posterior surfaces of the forearm.

Describe the different orientations of muscle fascicles, give an example of each, and explain how a muscle's shape is related to its force of contractions and the range of movement the contraction produces.

There are five classes of muscle shapes as determined by the arrangement of its fascicles. The five classes are circular convergent, parallel, pennate, and fusiform. Within some of the classes, there are different patterns based on the shape of the particular muscle, including triangular, trapezium, rhomboidal, and quadrate. Circular muscles have their fascicles arranged in a circle around an opening and act as sphincters (constrictors) to close the opening. Examples of circular muscles are those that surround the eyes, called the orbicularis oculi, and those that surround the mouth, called the orbicularis iris. Convergent muscles have fascicles that join at one common tendon from a wide area, which creates muscles that are triangular in shape. Having fibers that lie side by side can result in muscles with less strength if the total number of fibers is low. However, if the fibers are long, these muscles can have a large range of motion. One example of convergent muscles with many long fibers is the pectoralis muscles of the chest. Parallel muscles, similarly to convergent muscles, have fascicles that are organized parallel to the long axis of the muscle, but they terminate on a flat tendon that spans large degree because the fascicles are in a direct line with the tendon; however, they contract with less force because fewer total fascicles are attached to the tendon. In addition to those show in table 10.1, the hyoid muscles in the neck are examples of parallel muscles. Pennate muscles have fascicles that emerge like the bars on a feather from a common tendon that runs the length of the entire muscle. The location of the fascicles relative to the tendon is the basis for different types of pennate muscles. In unipennate muscles, the fascicles are on one side of the tendon. Bipennate muscles have fascicles arranged on two sides of the tendon. Multipennate muscles are those with fascicles arranged at many places around the central tendon. The long tendons of pennate muscles can extend for some distance between a muscle belly and its insertion. The pennate arrangement allows a large number of fascicles to attach to a single tendon, with the force of contraction concentrated at the tendon. The muscles that extend the knee, as well as the deltoid muscle as shown in table 10.1, are multipennate muscles. Fusiform muscles are those whose fascicles run the length of the entire muscle and taper at each end to terminate at tendons. Fusiform muscles have a wider belly than the ends of muscle. Because their fibers are long, but are commonly numerous, these muscles generally tend to be stronger than other muscles with parallel fascicle arrangements. The biceps brachii, which flexes the forearm, is an example of a fusiform muscle.

FIGURE 10.2 Levers

There are three classes of levers depending on the location of joints.

How many classes of levers are there?

There are three classes, or types, of levers based on the location of the fulcrum, weight, and force along the lever.

How is the erector spinae subdivided?

These back muscles are very strong to maintain erect posture. The erector spinae group of muscles on each side of the back consists of three subgroups: (1) the iliocostalis, (2) the longissimus, and (3) the spinals. The longissmimus group accounts for most of the muscle mass in the lower back. The deepest muscles of the back attach between the spinous and transverse processes of individual vertabrae.

How are extrinsic foot muscles divided?

These extrinsic foot muscles are divided into three groups, each located within a separate compartment of the leg: anterior, posterior, and lateral.

What do head and neck muscles function in?

These function primarily in lateral head movement. Most of the flexors of the head and neck lie deep within the neck along the anterior margins of the vertebral bodies (not illustrated). Extension of the neck is accomplished by the posterior neck muscles that attach to the occipital bone and mastoid process of the temporal bone, functioning as a class I lever system. These muscles also rotate and laterally flex the neck.

What do the muscles of the calfs do?

These muscles plantar flex the foot. The deep muscles of the posterior compartment plantar flex and invert the foot and flex the toes.

What does the abductor pollicis longus, extensor pollicis longus and the extensor pollicis brevis form?

These tendons form the sides of a depression on the posterolateral side of the wrist called the "anatomical snuffbox". When snuff was in use, a small pinch could be placed into the anatomical snuffbox and inhaled through the nose.

What is unusual about the insertion (and sometimes the origin) of facial muscles?

They originate from the skull and fibrous structures and use an elastic tendon in order to radiate to the skin. These muscles are unique in the way that they are positioned surrounding facial openings, such as the ears, eyes, nose, and mouth, while also having to stretch across the entirety of the skull and neck.

What does the pectoralis major do?

This muscle flexes the extended shoulder and extends the flexed shoulder. Try these movements and notice the position and action of the muscle.

How many groups of muscles have been identified based on their location in the thigh?

What movements are produced by the three muscle compartments of the leg? Name the muscles of each compartment, and describe the movements for which each muscle is responsible.

Three groups of thigh muscles have been identified based on their location in the thigh and are organized into compartments: (1) The muscles of the anterior compartment flex the hip and/or extend the knee (2) the muscles of the medial compartment adduct the thigh and (3) the muscles of the posterior compartment extend the hip and flex the knee. Anterior Compartment -Quadriceps femoris Extends knee; rectus fermoris also flexes hip -Sartorius Flexes hip and knee; rotates thigh laterally and leg medially Medial Compartment -Adductor brevis Adducts and laterally rotates thigh; flexes hip -Adductor longus Adducts and laterally rotates thigh; flexes hip -Adductor magnus Adductor part: adducts thigh and flexes hip Hamstring part: extends hip and adducts thigh -Gracilis Adducts thigh; flexes knee -Pectineus Adducts thigh; flexes hip Posterior Compartment -Biceps femoris Flexes knee; laterally rotates leg; extends hip -Semimebranosus Flexes knee; medially rotates leg; tenses capsule of knee joint; extends hip -Semitendinosus Flexes knee; medially rotates leg; extends hip

How is it possible for thigh muscles to move both the thigh and the leg? Name the six muscles that can do this, and give their actions.

Contrast the movements produced by the extrinsic and intrinsic tongue muscles.

Tongue consists of a mass of intrinsic muscles, which are found entirely within the tongue, and are involved in changing the shape fo the tongue, and extrinsic muscles, which are outside of the tongue but attached to it, and help change the shape of and move the tongue.

Explain the difference between doing chin-ups with the forearm supinate and doing them with it pronated. The action of which muscle predominates in each type of chin-up? Which type is easier? Why?

When doing chin up with your arms pronated or supinated this causes you work different muscles of your body. When the arms are supinated you work your biceps and shoulders When the arms are pronated you work you Infraspinatus, Teres minor and teres major. Doing chin ups with your arms supinated is easier because you use your arm muscles which are stronger because of everyday use compared to back muscles that aren't often used.

What happens when muscles contract?

When muscles contract, the pull (P), or force, of muscle contraction is applied to the levers (bones), causing them to move a body part (the weight). In figure 10.2, you can see that the three classes of levers are classes I, II, and III.

What happens when the hyoid bone is fixed?

When the hyoid bone is fixed by the infra hyoid muscles so that the bone is stabilized from below, the supra hyoid muscles can help depress the mandible.

What does the iliopsoas flex?

When the thigh is fixed, the iliopsoas flexes the trunk on the thigh. For example, the iliopsoas does most of the work when a person does sit-ups.

What muscles elevate when we swallow?

When we swallow, muscles elevate the pharynx and larynx and then constrict the pharynx. Specifically, (1) the palatopharyngeus elevates the pharynx and (2) the salpingopharyngeus muscles then constrict the pharynx from superior to inferior, forcing food into the esophagus.

While driving to school on slick roads and taking on her cell phone, Rachel lost control of her car. The car left the road and hit a tree. Rachel was not wearing a seat belt, and her head slammed into the steering wheel, causing a fractured left mandible, as well as nerve damage. On examination, Rachel's tongue deviated toward the injured side of her face when she tried to stick out her tongue, and the left side of her tongue was paralyzed. The nerve damage affected which muscles of her tongue?

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