Anatomy ~ Chapter 11

Muscle Named According to Several Criteria

1 - Muscle Action - indicate primary function or movement of the muscle: flexor, extensor, and pronator - ex - the flexor digitorum longus muscle is a long muscle responsible for flexing the digits 2 - Specific Body Region - indicate muscle location - ex - rectus femoris is on the thigh (femur), and the tibialis anterior is on the anterior surface of the tibia 3 - Muscle Attachments - indicates origin &/or intersections - ex - the sternocleidomastoid attaches to the sternum, the clavicle (cleido), and the mastoid process of the temporal bone 4 - Orientation of Muscle Fibers - indicate organization of muscle fascicles - ex - rectus abdominis muscle, rectus means "straight", internal and external oblique muscles are abdominal muscles that have angled muscle fibers

Facial Expression: General Characteristics

~ these muscles attach from the superficial fascia or skull bones to the superficial fascia of the skin - when these muscles contract, they pull on the skin, causing it to move - most of these muscles are innervated by the seventh cranial nerve (CN VII) - termed the facial nerve

Muscle Respiration: Intercostals & Diaphragm

~ External Intercostals - extend inferomedially from the superior rib to the adjacent inferior rib, assist in expanding the thoracic cavity by elevating the ribs during inspiration - Internal Intercostals - lie deep to the external intercostals, and their muscle fibers are at right angles to the external intercostals, depress the ribs only during forced expiration Diaphragm - is an internally placed, dome-shaped muscle that forms a partition between the thoracic and abdominal cavities, most important muscle associated with breathing (The term diaphragm refers to a muscle or group of muscles that covers or partitions an opening.) - The muscle fibers of the diaphragm converge from its margins toward a fibrous central tendon

Synergist

~ (syn = with, ergo = work) is a muscle that assists the agonist in performing its action - Usually, synergists are most useful at the start of a movement when the agonist is lengthened and cannot exert much power - ex - the biceps brachii of the arm is a synergist to the brachialis muscle of the arm (the agonist) when both work together to flex the elbow joint - fixators - synergists may also assist an agonist by preventing movement at a joint and thereby stabilizing the agonist

Appendicular Muscles

~ Control movements of upper and lower limbs - Control movements of pectoral and pelvic girdles - Organized into groups based on locations - the distal attachment typically is more movable than the proximal attachment, and when muscles contract, the distal attachment moves toward the proximal attachment

Forearm Muscles are Extrinsic to Wrist and Hand

~ Anterior Compartment - muscles arise from the medial epicondyle of the humerus via a common flexor tendon - Muscles in the anterior compartment of the forearm generally tend to flex the wrist, the metacarpophalangeal (MP) joints. - Some of these also flex the interphalangeal (IP) joints of the fingers ~ Posterior Compartment - muscles arise from the lateral epicondyle of the humerus via a common extensor tendon. - Muscles in the posterior compartment of the forearm tend to extend the wrist. - Some also extend the MP joints and the IP joints

Varied Organization of Fascicles

~ Bundles of muscle fibers, lie parallel to each other within each muscle, but the organization of fascicles in different muscles often varies - Fascicle Arrangement: circular, parallel, convergent, and pennate

Moves of Glenohumeral Joint

~ Latissimus Dorsi - is a broad, triangular muscle located on the inferior part of the back. - Often, it is referred to as the "swimmer's muscle," because its actions are required for many swimming strokes. - It is the prime arm extensor and adductor, and it medially rotates the arm. ~ Pectoralis Major - is a large, thick, fan-shaped muscle that covers the superior part of the thorax. - It is the principal flexor and adductor of the arm, and it medially rotates the arm - These muscles are antagonists with respect to arm flexion and arm extension - However, these two muscles work together (synergistically) when performing other movements, such as adducting and medially rotating the humerus.

Muscle Attachment

~ Most skeletal muscles extend between bones and cross at least one mobile joint. - Upon contraction, one of the bones moves while the other bone usually remains fixed. - origin - less movable attachment - insertion - more movable attachment - origin and insertion of muscles are not always easily determined by either movement or position

How are thigh muscles organized?

~ bound by the fascia lata, deep fascia that partitions them into compartments - anterior compartment muscles - extend the knee and flex the thigh - medial compartment muscles - adduct the thigh - lateral compartment muscles - abduct the thigh - posterior compartment muscles - flex knee and extend the thigh

Muscles of the Thigh: Medial Compartment

~ gracilis muscle - (in the medial compartment of the thigh) not only adducts and flexes the thigh

Fascicles 1: Circular Muscles

~ has concentrically arranged muscle fascicles around an opening - control material passage through an opening - sphincter - its contraction decreases the passageway diameter (closing the mouth)

Muscles Associated with the Mouth #2

~ mentalis - attaches to the lower lip, and when it contracts, it protrudes the lower lip (as when a person "pouts") - platysma - tenses the skin of the neck and pulls the lower lip inferiorly - If you stand in front of a mirror and tense the skin of your neck, you can see these thin muscles bulging out - buccinator - compresses the cheek against the teeth when we chew (and is the reason our cheeks don't bulge out like a squirrel's when we eat) - Infants use the buccinator when they suckle at the breast

Muscles of the Forearm Anterior Compartment

~ of the forearm may be subdivided into a superficial layer, an intermediate layer, and a deep layer. - The muscles of the superficial and intermediate layers arise from the common flexor tendon that attaches to the medial epicondyle of the humerus - superficial layer - of anterior forearm muscles is arranged from the lateral to the medial surface of the forearm in the following order: pronator teres (described previously), flexor carpi radialis, palmaris longus, and flexor carpi ulnaris. - The flexor carpi radialis - tendon is prominent on the lateral side of the forearm. This muscle flexes the wrist and abducts the hand at the wrist. - The palmaris longus - is absent in some individuals. This narrow, superficial muscle on the anterior surface of the forearm weakly assists in wrist flexion. - The flexor carpi ulnaris - flexes the wrist and adducts the hand at the wrist

Muscles of the Thigh: Posterior Compartment

~ posterior (flexor) compartment of the thigh contains the three hamstring muscles - These muscles also flex the leg. - The biceps femoris - is a two-headed muscle that attaches distally to the lateral side of the leg. - This muscle also can laterally rotate the leg when the leg is flexed. - The semimembranosus and semitendinosus - attach distally to the medial side of the leg, also medially rotate the leg when the leg is flexed

Muscle Named According to Several Criteria #2

5 - Muscle Shape - deltoid (shaped like a triangle), orbicularis (circular muscle fibers), rhomboid (shaped like a rhombus), and trapezius (shaped like a trapezoid) - small = brevis - long = longus - teres = long and round 6 - Muscle Size - Large muscles = magnus (big), major (bigger), or maximus (biggest) - Small muscles = minor (smaller) or minimus (smallest) - Ex - of muscles named by size include the buttocks muscles: gluteus maximus, gluteus medius, and gluteus minimus 7 - Number of Muscle Heads at an Attachment Site - how many muscle bellies or heads each contains at the superior or proximal attachment sites - ex - A biceps muscle has two heads at its proximal attachments, a triceps muscle has three heads, and a quadriceps muscle has four heads

Rectus Eye Muscles

1 ~ The medial rectus attaches to the anteromedial surface of the eye and pulls the eye medially (adducts the eye). It is innervated by CN III (oculomotor nerve). 2 ~ The lateral rectus attaches to the anterolateral surface of the eye and pulls the eye laterally (abducts the eye). This muscle is innervated by CN VI (abducens). (Notice that this nerve's name tells you the action of the muscle it innervates—the muscle abducts the eye.) 3 ~ The inferior rectus attaches to the anteroinferior part of the eye. The inferior rectus pulls the eye inferiorly (as when you look down) and medially (as when you look at your nose). The inferior and superior rectus muscles are innervated by CN III 4 ~ The superior rectus is located superiorly and attaches to the anterosuperior part of the sclera. The superior rectus pulls the eye superiorly (as when you look up) and medially (as when you look at your nose).

Axial Muscles

~ Have both origins and insertions on axial skeleton -Support and move the head and vertebral column -Function in facial expression, breathing, chewing and swallowing -Support and protect abdominal and pelvic organs - the superior attachment often (but not always) is more movable than the inferior attachment; thus, the superior portion of the body is pulled toward the inferior portion when the muscles contract - as in flexing your neck or doing an abdominal crunch

Hernia & Inguinal Hernia

~ Hernia - (rupture) condition in which a portion of the viscera, such as the intestine, protrudes through a weakened point of the muscular wall of the abdominopelvic cavity - A significant medical problem may develop if the herniated portion of the intestine swells, becoming trapped. Blood flow to the trapped segment may diminish, causing that portion of the intestine to die. - Inguinal Hernia - loop of small intestine protrudes through superficial inguinal ring - more likely to occur in males since there inguinal canals are larger to accommodate spermatic cord - high abdominal pressure (straining to lifting something heavy) can push intestine into canal - Physicians test for it by palpating inguinal ring while patient coughs (cough raising abdominal pressure)

Posterior Thoracic Muscles

~ Levator Scapulae - (elevates to scapula) arises from multiple heads on the transverse processes of the cervical vertebrae and attaches to the superior angle of the scapula - also inferiorly rotate the scapula so that the glenoid cavity moves inferiorly ~ Rhomboid Major and Rhomboid Minor - located deep to the trapezius - These rhomboid muscles are parallel bands that are directed inferolaterally from the vertebrae to the scapula. - They help elevate and retract (adduct) the scapula, as when you are standing up straight. - The rhomboid muscles also inferiorly rotate the scapula ~ Trapezius - is a large, diamond-shaped muscle that arises from the skull and vertebral column to both the scapula and the clavicle of the pectoral girdle laterally - The trapezius can elevate, depress, retract, or rotate the scapula, depending upon which fibers of the muscle are contracting

Muscles of Mastication

~ Mastication = process of chewing - these muscles move the mandible at the temporomandibular joint (TMJ) - There are four paired muscles of mastication: - temporalis (or temporal muscle) - is a broad, fan-shaped muscle that extends from the temporal lines of the skull and attaches to the coronoid process of the mandible. It elevates and retracts (pulls posteriorly) the mandible - masseter - elevates and protracts (pulls anteriorly) the mandible. It is the most powerful and important of the masticatory muscles. This short, thick muscle is superficial to the temporalis. - The lateral and medial pterygoid muscles - arise from the pterygoid processes of the sphenoid bone and attach to the mandible. Both pterygoids protract the mandible and move it from side to side during chewing. These movements maximize the effectiveness of the teeth while chewing or grinding foods of various consistencies. The medial pterygoid also elevates the mandible.

Anterior Thoracic Muscles

~ Pectoral Minor - is deep to the pectoralis major. - This muscle helps depress and protract (pull anteriorly) the scapula. - When your shoulders are hunched forward, the pectoralis minor muscle is contracting ~ Serratus Anterior - is a large, flat, fan-shaped muscle positioned between the ribs and the medial border of the scapula, this muscle helps stabilize the scapula against the posterior side of the rib cage - functions as both the agonist (prime mover) in scapula protraction and also is a powerful superior rotator of the scapula by moving the glenoid cavity superiorly, as occurs when you abduct the upper limb ~ subclavius extends from the clavicle to the first rib, and its main action is to stabilize and depress the clavicle

Tendon/ Aponeurosis

~ Tendon - attaches the muscle to bone, skin, or another muscle - Tendons usually have a thick, cordlike structure. - Sometimes, the tendon forms a thin, flattened sheet, termed an aponeurosis (apo = from, neuron = sinew)

Muscles Associated with the Mouth

~ The mouth is the most expressive part of the face - The orbicularis oris consists of muscle fibers that encircle the opening of the mouth, when this muscle contracts, you close your mouth - when you "pucker up" for a kiss, you are using this muscle - The depressor labii inferioris does what its name suggests—it pulls the lower lip inferiorly. - The depressor anguli oris is considered the "frown" muscle, because it pulls the corners of the mouth inferiorly.

Muscles of the Anterior Neck: The Hyoid Muscles

~ The muscles of the anterior neck are divided into the suprahyoid muscles, which are superior to the hyoid bone, and the infrahyoid muscles, which are inferior to the hyoid bone - stylohyoid bone - connects the styloid process of the skull and the hyoid bone. Upon contraction, it elevates the hyoid bone, causing the floor of the oral cavity to elongate during swallowing - thyroid cartilage of the larynx to the hyoid bone. It depresses the hyoid bone and elevates the thyroid cartilage to close off the larynx during swallowing. In addition, the omohyoid, sternohyoid, and thyrohyoid help anchor the hyoid so the digastric can depress the mandible

Oblique Eye Muscles

~ The oblique eye muscles arise from within the orbit and attach to the posterolateral part of the sclera of the eye. - The inferior oblique elevates the eye and turns the eye laterally. Since this muscle attaches to the inferior posterior part of the eye, contracting this muscle pulls the posterior part of the eye inferiorly (but elevates the anterior part of the eye). This muscle is innervated by CN III. - The superior oblique depresses the eye and turns the eye laterally. This muscle passes through a pulleylike loop, called the trochlea, in the anteromedial orbit. This muscle attaches to the superior posterior part of the eye, so contracting this muscle pulls the posterior part of the eye superiorly (but depresses the anterior surface of the eye). This muscle is innervated by CN IV (trochlear). (Notice that this nerve's name is derived from the trochlea that holds the superior oblique in place.)

Muscles that Move the Tongue

~ The tongue is an agile, highly mobile organ. It is composed of intrinsic muscles that compose the tongue, which curl, squeeze, and fold the tongue during chewing and speaking. ~ The extrinsic muscles of the tongue arise from other head and neck structures and attach to the tongue. - The extrinsic muscles end in the suffix -glossus = tongue - These extrinsic tongue muscles are used in various combinations to accomplish the precise, complex, and delicate tongue movements required for proper speech and food manipulation within the mouth. - Most of these muscles are innervated by CN XII, the hypoglossal nerve

Posterior Neck Muscles

~ The trapezius attaches to the skull and helps extend the neck(gradually) - but its primary function is to help move the pectoral girdle - When the left and right splenius capitis, splenius cervicis, semispinalis capitis, and longissimus capitis muscles bilaterally contract, they extend the neck - Unilateral contraction rotates (turns) the head and neck to the same side

Pharynx Muscles (Neck)

~ Throat muscles, is a funnel-shaped tube that lies posterior to both the oral and nasal cavities, several muscles help form or attach to this tube and aid in swallowing - The primary pharynx muscles are the pharyngeal constrictors (superior, middle, and inferior). - When food is swallowed and enters the pharynx, these muscles contract sequentially to initiate swallowing and force the bolus inferiorly into the esophagus

Arm

~ Triceps Brachii - long head originates on scapula, spans shoulder joint, helps extend and adduct the arm ~ Biceps Branchii - both heads originate on scapula and span shoulder joint, assist inn flexing the arm ~ Deltoid - Prime abductor of the arm, its anterior fibers flex and medially rotate the arm, lateral fibers abduct the arm, its posterior fibers extend and laterally rotate arm Teres Major - works synergistically with the latissimus dorsi by extending, adducting, and medially rotating the arm

Muscle Respiration

~ Two posterior thorax muscles assist with respiration - The serratus posterior superior - attaches to ribs 2-5 and elevates these ribs during forced inspiration, thereby increasing the lateral dimensions of the thoracic cavity. - The serratus posterior inferior - attaches to ribs 8-12 and depresses those ribs during forced expiration. (Normal, quiet expiration takes no active muscular effort.) - scalene muscles - (discussed previously with other neck muscles) - help elevate the first and second ribs during forced inspiration, thereby increasing the dimensions of the thoracic cavity.

Agonist

~ also called a prime mover, is a muscle that contracts to produce a particular movement- such as extending the forearm - triceps brachii on the posterior side of the humerus is an agonist when it causes extension of the forearm

Muscles of the Thigh: Anterior Compartment

~ anterior (extensor) compartment of the thigh is composed of the large quadriceps femoris, the prime mover of knee extension - The quadriceps femoris is a composite muscle with four heads: the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. - All four muscles converge on a single quadriceps tendon, which extends to the patella and then continues inferiorly as the patellar ligament and attaches distally to the tibial tuberosity - Sartorius - which acts on both the hip and knee joints, flexing and laterally rotating the thigh while flexing and medially rotating the leg. This muscle is the longest in the body and is termed the tailor's muscle because it helps us sit cross-legged, as tailors used to do

Erector Spinae

~ are used to maintain posture and to help an individual stand erect. - When the left and right erector spinae muscles contract together, they extend the vertebral column. - If the erector spinae muscles on only one side contract, the vertebral column flexes laterally toward that side 1 - iliocostalis group - is the most laterally placed of the three erector spinae components. - It is composed of three parts: cervical, thoracic, and lumbar, which attach either to the angles of the ribs or to the transverse processes of cervical vertebrae. 2 - longissimus group is medial to the iliocostalis group. The fibers of the longissimus muscle group attach to the transverse processes of the vertebrae. - The longissimus group is composed of three parts: capitis, cervical, and thoracic. 3 - spinalis group is the most medially placed of the erector spinae muscles. - The spinalis muscle fibers attach to the spinous processes of the vertebrae. - The spinalis group is composed of cervical and thoracic parts.

Posterior Compartment

~ contains elbow extensors, so this compartment is also called the extensor compartment. - These muscles receive their blood supply from the deep brachial artery and are innervated by the radial nerve. The primary muscle in this compartment is the triceps brachii. - Put your hand on your posterior arm, and then extend your elbow. ~ triceps brachii - is the large, three-headed muscle on the posterior surface of the arm. The long head of the triceps brachii also crosses the glenohumeral joint, where it helps extend the humerus

Leg Muscles That Move the Ankle, Foot, and Toes

~ crural muscles - The deep fascia partitions the leg musculature into three compartments (anterior, lateral, and posterior), each with its own blood supply and innervation, and muscles in the same compartment tend to share common functions - some of these muscles also help flex the leg

Muscles of Medial Compartment of Thigh

~ dductor longus, adductor brevis, adductor magnus, gracilis, and pectineus also flex the thigh. - The adductor magnus also extends and laterally rotates the thigh. - The obturator externus does not adduct the thigh, but it laterally rotates the thigh

Facial Expression: Muscles of Forehead, Scalp, and Eyebrow

~ epicranius is composed of the occipitofrontalis muscle and a broad epicranial aponeurosis, also called the galea aponeurotica - The frontal belly of the occipitofrontalis is superficial to the frontal bone on the forehead - When this muscle contracts, it raises the eyebrows and wrinkles the skin of the forehead. - The occipital belly of the occipitofrontalis covers the posterior aspect of the skull. - When this muscle contracts, it retracts the scalp slightly.

Fascicles 4: Pennate Muscles

~ fibers pull at an angle to tendon - more tension than does a parallel muscle (but do not pull as far) of the same size, and thus it exerts a greater force. Three Subtypes: 1 - unipennate muscle - all of the muscle fascicles are on the same side of the tendon - ex - the extensor digitorum, a long muscle that extends the fingers 2 - bipennate muscle - the most common type, has muscle fascicles on both sides of the tendon - ex - the interosseous muscles on both the palmar and dorsal sides of the metacarpals, help adduct and abduct the digits 3 - multipennate muscle - has branches of the tendon within the muscle and fascicles arranged on both sides of each tendon branch - ex - the triangular deltoid that covers the superior surface of the shoulder joint

Posterior Thigh Muscles

~ gluteus maximus - is the largest of the three gluteal muscles; it is the chief extensor of the thigh and it laterally rotates the thigh. - gluteus medius and gluteus minimus - Deep to the gluteus maximus, which abduct and medially rotate the thigh - organized from superior to inferior within the posterior thigh as the piriformis, superior gemellus, obturator internus, inferior gemellus, and quadratus femoris - Deep to the gluteal muscles are a group of muscles that collectively laterally rotate the thigh, as when the legs are crossed with one ankle resting on the knee - Hamstrings - because a ham is strung up by these muscles while being smoked - The hamstring muscles are the biceps femoris, semimembranosus, and semitendinosus. - These muscles share a common proximal attachment on the ischial tuberosity of the os coxae, and they attach distally on the leg. - Thus, these muscles move both the thigh and the knee. Their primary thigh movement is extension

Pelvic Floor Muscles

~ have two important functions; they provide 1; physical support to the pelvic viscera 2; constrictor mechanism to the anal canal, vagina and urethra. Perineum - the diamond-shaped region between the lower appendages

Intermediate Layer

~ in the anterior compartment of the forearm contains a single muscle. - The flexor digitorum superficialis - splits into four tendons, each of which attaches distally to the middle phalanges of fingers 2-5. - deep layer of the forearm anterior compartment muscles includes the flexor pollicis longus (lateral side), the flexor digitorum profundus (medial side), and the pronator quadratus (deep) - flexor pollicis longus attaches to the distal phalanx of the thumb and flexes the MP and IP joints of the thumb.

The Process of Muscle Respiration

~ inspiration - several muscles contract to increase the dimensions of the thoracic cavity to allow the lungs to fill with air - expiration - some respiratory muscles contract and others relax, collectively decreasing the dimensions of the thoracic cavity and forcing air out of the lungs - The muscles of respiration are on the posterior and anterior surfaces of the thorax. - These muscles are covered by more superficial muscles (such as the pectoral muscles, trapezius, and latissimus dorsi) that move the upper limb.

Antagonist

~ is a muscle whose actions oppose those of the agonist - the tension within the muscle being lengthened is adjusted to control the speed of the movement and ensure that it is smooth. - ex - When the triceps brachii acts as an agonist to extend the forearm, the biceps brachii muscle on the anterior side of the humerus acts as an antagonist to stabilize the movement and to produce the opposing action, which is flexion of the forearm

Muscles of the Anterior Neck: Sternocleidomastoid

~ is a thick, cordlike muscle that extends from the sternum and clavicle to the mastoid process posterior to the ear - bilateral (both sides) contraction flexes neck - unilateral (one side) contraction causes lateral flexion of head to contracting muscle's side and rotation of head to opposite side - Thus, if the left sternocleidomastoid muscle contracts, it rotates the head to the right side of the body. The three scalene muscles (anterior, middle, and posterior) work with the sternocleidomastoid to flex the neck. - the scalene muscles elevate the first and second ribs during forced inspiration - sternohyoid extends from the sternum to the hyoid bone, where it depresses the hyoid bone

Muscles of Leg: Lateral Compartment

~ leg muscles contain two synergistic muscles that are very powerful evertors of the foot and weak plantar flexors - fibularis longus (peroneus brevis)- (long, flat muscle) attaches distally to the plantar side of the foot. The fibularis brevis (peroneus brevis) lies deep to the fibularis longus, and its tendon attaches distally to the base of the fifth metatarsal

Muscles of the Leg: Anterior Compartment

~ leg muscles dorsiflex the foot, extend the toes, or both - extensor digitorum longus - dorsiflexes the foot and extends toes 2-5 - extensor hallucis longus - sends a tendon to the dorsum of the great toe (hallux), and so it dorsiflexes the foot and extends the great toe - fibularis tertius (peroneus tertius) - dorsiflexes and weakly everts the foot - tibialis anterior - is the primary dorsiflexor of the foot. This muscle attaches to the medial plantar side of the foot, so it also inverts the foot

Extrinsic Eye Muscles

~ move the eyes - They are termed extrinsic because they attach to the outer white surface of the eye, called the sclera - There are six extrinsic eye muscles: the four rectus muscles (medial, lateral, inferior, and superior) and the two oblique muscles (inferior and superior)

Fascicles 3: Convergent Muscles

~ muscle has widespread muscle fascicles over a broad area that converge on a common attachment site - raphe - this attachment site may be a single tendon, a tendinous sheet, or a slender band of collagen fibers - These muscle fibers are often triangular in shape, resembling a broad fan with a tendon at the tip - versatile—when the fibers in a convergent muscle all contract at once, they do not pull as hard on the tendon as a parallel muscle of the same size because the muscle fibers on opposite sides of the tendon are not working together; rather, they are pulling in different directions. - example - pectoralis major of the chest.

Muscles of Leg: Posterior Compartment

~ of the leg is composed of seven muscles separated into superficial and deep groups, superficial muscles and most of the deep muscles plantar flex the foot at the ankle - gastrocnemius (gastr = belly, kneme = leg) - has two thick muscle bellies that form the prominence on the posterior part of the leg often referred to as the "calf." -This muscle spans both the knee and the ankle joints; it flexes the leg and plantar flexes the foot - soleus - is a broad, flat muscle deep to the gastrocnemius (solea = sandal). - This muscle plantar flexes the foot. - The gastrocnemius and soleus are collectively known as the triceps surae, and together they are the most powerful plantar flexors of all the leg muscles

Deep Layer of Posterior Compartment of Leg

~ of the posterior compartment contains four muscles - flexor digitorum longus - attaches to the distal phalanges of toes 2-5, plantar flexes the foot, and flexes the MP, PIP, and DIP joints of these toes

Muscles of the Eyelids

~ orbicularis oculi - consists of circular muscle fibers that surround the eye's orbit, when this muscle contracts, the eyelid closes, as when you wink, blink, or squint. - The levator palpebrae superioris elevates the upper eyelid when you open your eyes.

Posterior Compartment, Superficial Layer

~ posterior compartment muscles may be subdivided into a superficial layer and a deep layer, of the forearm are primarily wrist and finger extensors. An exception is the supinator, which helps supinate the forearm - superficial layer - of posterior forearm muscles arises from a common extensor tendon on the lateral epicondyle of the humerus - extensor carpi radialis longus - is medial to the brachioradialis. It extends the wrist and abducts the hand at the wrist. - extensor digitorum - splits into four tendons that attach distally to the distal phalanges of fingers 2-5. It extends the wrist, MP joints, PIP joints, and DIP joints of fingers 2-5 - extensor digiti minimi - attaches to the distal phalanx of the pinky (finger 5). It works with the extensor digitorum to extend the little finger. - On the medial surface of the posterior forearm, the extensor carpi ulnaris - attaches distally to the fifth metacarpal bone, where it acts to extend the wrist and adduct the hand

Anterior Compartment

~ primarily contains elbow flexors, so it is also known as the flexor compartment. - Muscles in this compartment are supplied by the deep brachial artery and are innervated by the musculocutaneous nerve. - Muscles in this compartment include the coracobrachialis (note that this muscle is an arm flexor and not an elbow flexor), biceps brachii, brachialis, and brachioradialis muscles. ~ biceps brachii - is a large, two-headed muscle on the anterior surface of the humerus. This muscle flexes the elbow joint, and it is a powerful supinator of the forearm when the elbow is flexed ~ brachialis - is deep to the biceps brachii on the anterior surface of the humerus. It is the most powerful flexor of the forearm at the elbow ~ brachioradialis - is another prominent muscle on the anterolateral surface of the forearm. It is a synergist in elbow flexion, effective primarily when the prime movers of forearm flexion have already partially flexed the elbow

Muscles Of Forearm and Elbow Joint

~ pronator teres and pronator quadratus - rotate the radius across the surface of the ulna to pronate the forearm, anterior compartment of the forearm ~ antagonistic to the supinator - in the posterior compartment of the forearm. - supinator works synergistically with the biceps brachii to supinate the forearm

Rotator Cuff Muscles and Injuries

~ provide the strength and stability of the glenohumeral joint, these muscles attach the scapula to the humerus 1 - Subscapularis - is used when you wind up for a pitch. It medially rotates the arm 2 - Supraspinatus - is used when you start to execute the pitch, by fully abducting the arm 3 - infraspinatus and teres minor - help slow down the pitching arm upon completion of the pitch. - These two muscles adduct and laterally rotate the arm Injuries - - can be caused by repetitive use - can be caused by falling on the shoulder or lifting too heavy of an object - supraspinatus most commonly involved - symptoms: swelling, tenderness, and pain with movement - common in baseball players

Muscle Attaching to Anterior Thigh

~ psoas major and the iliacus - originate on the lumbar vertebrae and ilium, respectively, but they share the distal attachment at the lesser trochanter of the femur, work synergistically to flex the thigh - Because the two muscles merge and attach to the femur, they are collectively referred to as the iliopsoas

Fascicles 2: Parallel Muscle

~ run parallel to its long axis. - cylindrical with an expanded central region. - have a central body, called the belly, or gaster - contracts and shortens = the muscle increases in diameter - Parallel muscles have high endurance but are not strong. - Examples: rectus abdominis (an anterior abdominal muscle) & biceps brachii arm.

Abdominal Wall 1

~ superficial external oblique - muscle fibers are directed inferomedially - The external oblique is composed of muscle along the lateral abdominal wall and forms an aponeurosis as it projects anteriorly. - Inferiorly, the aponeurosis of the external oblique forms a strong, cordlike inguinal ligament that extends from the anterior superior iliac spine to the pubic tubercle. - Immediately deep to the external oblique is the internal oblique - muscle fibers project superomedially, which is at right angles to the external oblique. - Like the external oblique, this muscle forms an aponeurosis as it projects anteriorly. - Unilaterally, the external oblique on one side of the body and the internal oblique on the opposite side of the body work together to rotate the vertebral column.

Muscle Attachment of Lateral Thigh

~ tensor fasciae latae - It attaches to a lateral thickening of the fascia lata, called the iliotibial tract (or iliotibial band), which extends from the iliac crest to the lateral condyle of the tibia. -abducts and medially rotates the thigh

Other Muscles of Vertebral Column

~ these muscles aid in moving the vertebral column - transversospinalis muscles - Deep to the erector spinae, a group of muscles, connect and stabilize the vertebrae. This group includes several specific muscles - quadratus lumborum muscles - are located primarily in the lumbar region. When the left and right quadratus lumborum muscles bilaterally contract, they extend the vertebral column. - When either the left or right quadratus lumborum muscle unilaterally contracts, it laterally flexes the vertebral column

Abdominal Wall 2

~ transversus abdominis - deepest muscle, whose fibers project transversely across the abdomen and which has an aponeurosis as it projects anteriorly - When the transversus abdominis unilaterally contracts, it laterally flexes the vertebral column. - The rectus abdominis - is a long, straplike muscle that extends vertically the entire length of the anteromedial abdominal wall between the sternum and the pubic symphysis. - It is partitioned into four segments by three fibrous tendinous intersections, which form the traditional "six-pack" of a muscular, toned abdominal wall. - The rectus abdominis is enclosed within a fibrous sleeve called the rectus sheath, which is formed from the aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles. - The left and right rectus sheaths are connected by a vertical fibrous strip termed the linea alba