Human A & P Chapter 10: The Muscular System

Define the following terms -lever -fulcrum -effort -load

-A bar that moves a fixed point when a force is applied to it -The fixed point -The applied force that moves a resistance -The resistance

What muscle is the prime mover of finger extension and abduction? What nerve is it innervated by?

-Extensor digitorum -posterior interosseous nerve (branch of radial nerve)

A muscle that crosses on the anterior side of a joint produces...

-Flexon -pectorialis major

What muscle is the prime mover of hand flexion and abduction? What nerve is it innervated by?

-Flexor carpi radialis -median nerve

What is the prime mover of wrist and middle phalanges flexion? What nerve is it innervated by?

-Flexor digitorum superficialis -Medial nerve

What is the prime mover for flexing the thigh? What is its insertion?

-Illopsoas muscle composed of the illacus (innervated by femoral nerve) and psoas major (innervated by ventral rami) muscles -lesser trochanter of femur

What is mechanical advantage (also called the power lever)? Give example.

-The load is closer to the fulcrum and the effort is applied far from the fulcrum -lifting a car with a lever

What is mechanical disadvantage? Give example.

-The load is far from the fulcrum and the effort is applied near the fulcrum -wielding a shovel

*Of the muscles illustrated, which could shorten most? Which two would likely be the most powerful? Why?*

-The sartorius -deltoid and rectus femoris because they have more muscle fibers

A muscle that crosses on the lateral side of a joint produces...

-abduction -deltoid middle

A muscle that crosses on the medial side of a joint produces...

-adduction -teres major

Which 3 anterior arm muscles flex the forearm? (List in order of descending strength)

-brachialis -biceps brachii -brachioradialis

Zygomatics: Description Origin and Insertion Action Nerve supply

-check bone muscle pair -zygotmatic bone; skin and muscle at corner of mouth -smiling -Facial Nerve, VII

Buccinator: Description Origin and Insertion Action Nerve supply

-cheek muscle deep to masseter -maxialla and mandible; orbicularis oris -compresses cheek, holds food -Facial, VIII

What are circular fascicles arranged in? Give example.

-concentric rings -orbicularis oris

Gluteus Medius: Description Origin and Insertion Action Nerve supply

-covered by the gluteus maximus -beteween gluteal lines on lateral ilium; lateral greater trochanter of femur by tendon -abducts and medially rotates thigh, steadies pelvis, important in walking -superior gluteal nerve, lumbosacral plexus

Frontalis: Description Origin and Insertion Action Nerve supply

-covers forehead, no body attachments -epicranial aponeurosis; skin of eyebrows and roof of nose -raises eyebrowns, wrinkles forehead -Facial Nerve, VII

Masseter Description Origin and Insertion Action Nerve supply

-covers lateral mandiubular ramus -zygomatc bone; ramus of mandible -prime jaw mover in elevation -Trigeminal, V

Temporalis: Description Origin and Insertion Action Nerve supply

-covers part of temporal, frontal, and parietal bones -temporal fossa; coronoid process of mandible -closes and retracts jaw -Trigeminal, V

Pectoralis major: Description Origin and Insertion Action Nerve supply

-covers superior chest -sternal end of clavicle, sternum, ribs 1-6; greater tubercle of humerus -adducts and medially rotates arm, antagonist of flexion and extension -pectoral nerves; Cervical Plexus

Semimembranosus: Description Origin and Insertion Action Nerve supply

-deep to semitendinosus -ischial tuberosity; medial condyle of tibia -extends thigh and flexes leg, medially rotates leg -Sciatic nerve (tibial)

Sternocleidomastoid: Description Origin and Insertion Action Nerve supply

-deep to the platysma -manubrium of sternum; mastoid process of temporal bone -flexes and laterally rotates head -Accessory, XI; Cervical Plexus

Internal Intercoastals: Description Origin and Insertion Action Nerve supply

-deep, 11 pairs on ribs, right angles -superior border of rib below; costal groove of rib above -depress rib cage, forced expiration -Intercostal nerves

Transverse Rectus: Description Origin and Insertion Action Nerve supply

-deepest muscle of abdominal wall -inguinal ligament, last 6 ribs, lumbar fascia; linea alba, pubic crest -compress abdominal contents -Intercostal nerves

What is the prime mover of arm abduction? Which two muscles are the main adductors?

-deltoid -pectoralis major and latissimus dorsi

A muscle that crosses on the posteior side of a joint produces...

-extension -latissimus dorsi

What are the muscles of respiration?

-external intercostals -intetnal intercostals -diaphragm

What are pennate fascicles? What are the 3 forms?

-fascicles and muscle fibers that are short and attach obliquely (1) unipennate (2) bipennate (3) multipennate

What are convergent fascicles? Give example.

-fascicles that converge toward a tendon of insertion -pectoralis major muscle (fan shaped)

What are parallel fascicles? Give example.

-fascicles that run parallel to muscle. They are straplike or spindle shaped -biceps brachii (spindle shaped/Fusiform)

Internal Oblique: Description Origin and Insertion Action Nerve supply

-fibers run upward and medially -lumbar fascia, illiac crest, inguinal ligament; last 3-4 ribs, linea alba -same as external oblique -Intercostal nerves

What are synergists that immobilize a bone or a muscle? Give example.

-fixators -fixator muscles that immobilize the scapula

Which muscle is a prime mover of hand flexion and adduction? What nerve is it innervated by?

-flexor carpi ulnaris -ulnar nerve

Diaphragm: Description Origin and Insertion Action Nerve supply

-forms floor of the thoracic cavity, pierced by the aorta -inferior rib cage; centeral tendon -prime mover of inspiration -Phrenic nerves

Subscapularis: Description Origin and Insertion Action Nerve supply

-forms posterior wall of axilla -subscapular fossa of scapula; lesser tubercle of humerus -cheif medial rotator of arm assisted by pectoralis major; holds humerus head in glenoid cavity -subscapular nerves, cervical plexus

Deltoid: Description Origin and Insertion Action Nerve supply

-forms rounded shoulder mass -insertion of trapezius, lateral clavicle, acromion and spine of scapula; deltoid tuberosity of humerus -prime mover of arm abduction -Axillary Nerve; Cervical Plexus

Piriformis: Description Origin and Insertion Action Nerve supply

-inferior to gluteus minimus, issues from pelvis via sciatic notch -sacrum opposite greater sciatic notch; superior greater trochanter of femur -rotates extended thigh laterally -sacral plexus

Teres minor: Description Origin and Insertion Action Nerve supply

-inferior to intraspinatus muscle -lateral border of dorsal scapula; greater tubercle of humerus -same as infraspinatus muscle -Axillary nerve

Muscle contraction provides the effort that is applied at the muscle's (blank) point on a bone. The load is the...

-insertion -the bone, tissues, and anything else being moved with it

Gluteus maximus: Description Origin and Insertion Action Nerve supply

-largest and most superifical gluteus, covers ischial tuberosity (standing), exposed ischial tuberosity (sitting) -dorsal illum, sacrum, and coccyx; gluteal tuberosity of femur, illotibial tract -major extensor of thigh -Inferior gluteal nerve, lumbosacral plexus

Supraspinatus: Description Origin and Insertion Action Nerve supply

-located on posterior scapula, deep to trapezius -supraspinous fossa of scapula; superior part of greater tubercle of humerus -initates abduction of arm, prevents dislocation of humerus -suprascapular nerve

What is the function of the agonist? Give example.

-major responsibility for producing a particular movement -pectoralis major muscle, agonist of arm flexion

Which four muscles are involved in mastication? Which are prime jaw movers?

-masseter, prime -temporalis, prime -buccinator -pterygoid

Rectus abdominis: Description Origin and Insertion Action Nerve supply

-medial superficial miscle, extend from pelvis to rib cage, six pack -pubic symphysis; xiphoid process, costal cartilage of ribs 5-7 -flex and rotate lumar region, sit ups and curls -Intercoastal nerves

Semitendinosus: Description Origin and Insertion Action Nerve supply

-medial to biceps femoris -ischial tuberosity; medial upper tibial shaft -extends thigh and flexes leg, medially rotates leg with semimembranosus -Sciatic nerve (tibial)

Bicepts femoris: Description Origin and Insertion Action Nerve supply

-most lateral of the group -ischial tuberosity (long head) and distal femur(short head); head of fibula and lateral condyle of tibia by common tendon -extends thigh and flexes leg, laterally rotates leg when knee is flexed -Sciatic nerve (tibial and common fibular nerves)

External Oblique: Description Origin and Insertion Action Nerve supply

-most superifical, aponeurosis forms inguinal ligament -lower eight ribs; linea alba pubic crest -flex vertebral column, compress abdominal wall, oblique curls -interocastal nerves

Latissimus dorsi: Description Origin and Insertion Action Nerve supply

-muscle of lumbar region, covered superiorly by trapezius -thoracic and lumbar vertebrae, lower 3-4 ribs; inter-tubercular sulcus of humerus -prime mover of arm extension, powerful adductor, medially rotates arm at shoulder -Thoracodorsal nerve, Cervical Plexus

Triceps brachii: Description Origin and Insertion Action Nerve supply

-only muscle of posterior arm -long head: infraglenoid of scapula, lateral/medial head: posterior humerus shaft; by common tendon into olecranon of ulna -prime mover of arm extension -Radial Nerve, Brachial Plexus

What is the function of the antagonists? Give example.

-oppose or reverse a particular movement -latissimus dorsi muscle, antagonist of pectoralis major muscle, and agonist of arm extension

Occipitalis: Description Origin and Insertion Action Nerve supply

-overlies posterior occipital -occpital and temporal bones; epicranial aponeurosis -pulls scalp posteriorly -Facial Nerve, VII

*What criteria are used in naming each of the following muscles? Iliacus, adductor brevis, quadriceps femoris.*

-overlies the iliac bone -adducts the thigh -has 4 heads and is on the femur

Infraspinatus: Description Origin and Insertion Action Nerve supply

-partically covered by deltoid and trapezius -intraspinous fossa of scapula; greater tubercle of humerus -rotates arm laterally, holds head of humerus in glenoid cavity -suprascapular nerve

If the arm was rotating medially, which muscle would be the prime mover? Which the synergist?

-pectoralis major -deltoid

What 3 bones are prime movers of arm movement

-pectoralis major -latissiumus dorsi -deltoid muscles

What are the two pronators of the arm? Which nerve is each innervated by?

-pronator teres, median nerve -pronator quadratus, median nerve (prime mover)

What is most powerful muscle in the body? Where does it insert? What nerve innervates it?

-quadriceps femoris, sole knee extensor -into the patella via the patellar ligament into the tibial tuberosity -Femoral nerve, Lumbar Plexus

What are the 4 muscles that make up the quadricepts femoris?

-rectus femoris -vastus lateralis -vastus medialis -vastus intermedius

Medial pterygoid: Description Origin and Insertion Action Nerve supply

-runs along internal surface of mandible -medial surface of lateral pterygoid plate; medial surface of mandible -side to side jaw movements -Trigeminal, V

Plantaris: Description Origin and Insertion Action Nerve supply

-small muscle, may be absent -posterior femur above lateral condyle; calcaneus via tendon -Helps to flex leg and plantar flexes foot -Tibial nerve

Coracobrachialls: Description Origin and Insertion Action Nerve supply

-small, cylindrical muscle -coracoid process of scapula; medial humerus shaft -flexes and adducts arm -Musculocutaneous nerve, Brachial Plexus

Gluteus minimus: Description Origin and Insertion Action Nerve supply

-smallest and deepest gluteal muscle -between gluteal lines on illium; anterior greater trochanter of femur -same as gluteus medius -superior gluteal nerve, lumbosacral plexus

Orbicularis oculi: Description Origin and Insertion Action Nerve supply

-sphincter of eyelid -frontal and maxiallary bones; tissue of eyelid -blinking, drawing eyebrows together -Facial Nerve , VII

Direction of muscle fibers: Rectus Transverse Oblique

-straight -at right angles -slanting

Brachialis: Description Origin and Insertion Action Nerve supply

-strong muscle deep to bicepts branchii on distal humerus -front of distal humerus, embraces deltoid muscle insertion; coronoid process of ulna and capsule of elbow joint -major forearm flexor, lifts ulna as bicepts lifts radius -Musculocuataneous nerve

Tibialis anterior: Description Origin and Insertion Action Nerve supply

-superfical muscle of the anterior leg, parallels the tibia -lateral condyle of tibia and interossesous membrane; medial cuneiform and 1st metatarsal bone by tendon -prime mover of dorsiflexion, supports medial longitudinal arch, foot drop -Deep fibular nerve

Trapezius: Description Origin and Insertion Action Nerve supply

-superficial muscle of posterior thorax -occpital bone, C7, thoracic vertebrate; acromion and spine of scapula -adducts and elevates scapula, shoulder shrug -Accessory, XI; Cervical Plexus

External Intercostals: Description Origin and Insertion Action Nerve supply

-superficial, 11 pairs on the ribs, oblique. -inferior border of rib above; superior border of rib below -elevate rib cage, inspiration -Intercoastal nerves

Gastrocnemius: Description Origin and Insertion Action Nerve supply

-superifical muscle that forms proximal curve of calf -medial and lateral condyle of femur; posterior calcaneus -plantar flexes foot when leg is extended, can flex knee when foot is dorsiflexed -Tibial nerve

Platysma: Description Origin and Insertion Action Nerve supply

-superifical neck muscle -fasica of chest; lower mandible -tenses neck, depresses mandibule, pulls lower lip down -Facial, VIII

Brachioradialis: Description Origin and Insertion Action Nerve supply

-superior muscle of lateral forearm -lateral supracondylar ridge at distal humerus; base of radial syloid process -synergist in flexing forearm, stablizes elbow during rapid flexion and extension -Radial nerve

Lateral pterygoid: Description Origin and Insertion Action Nerve supply

-superior to medial pterygoid -greater wing and lateral pterygoid plate; condylar process of mandible -side to side movements of lower teeth, protracts mandible -Trigeminal, V

Bicepts branchii: Description Origin and Insertion Action Nerve supply

-two headed fusiform muscle -short head: coracoid process, long head: supraglenoid tubercle; by common tendon into radial tuberosity -Flexes and supinates forearm -Musculocutaneous, Brachial plexus

What movements does rotator cuff muscles act as synergist to?

Angular and rotational movements of the arm

What is the function of the synergists?

Assists agonist

What are the 3 hamstring muscles?

Biceps femoris Semitendinosus Semimembranosus

What are the 4 types of fascicle arrangements in muscles?

Circular Convergent Parallel Pennate

What is the erector spinae?

Deep back strap muscles that extend the spine by working together, or flex the spine by only one side contracting.

What is the anatagonist of the pectoralis major and latissimus dorsi, which adduct the arm?

Deltoid

Give an example of a multipennate muscle.

Deltoid muscle of the shoulder

Give an example of a unipennate muscle.

Extensor digitorum longus muscle of the leg

What muscle is the synergist of the diaphragm?

External intercostals

Which 3 muscles make up the layers of the abdominal wall?

External oblique Internal oblique Transversus abdominis

True or False: Muscles push, they never pull

False, muscles pull and they never push

What is a third class lever in the body? Where are the following Load Effort Fulcrum

Flexing the forearm by the biceps brachii -the hand and distal end of the forearm -proximal radius of the forearm -elbow joint

How is a second class level arranged?

Fulcrum, load, effort

What are the quadricepts antagonized by?

Hamstring muscles, prime movers of thigh extension and knee flexion

What muscle is the antagonist of the external intercoastals?

Internal intercostals

*What benefit is provided by a lever that operates at a mechanical advantage?*

It allows the muscle to exert less force than the load being moved

What is a first class lever in the body? Where are the following Load Fulcrum Effort

Lifting the head off the chest -weight of skeleton -atlanto-occipital joint -posterior neck muscles

How is a third class lever arranged?

Load, effort, fulcrum

How is a first class lever arranged?

Load, fulcrum, effort

What are muscles named according to? (7)

Location Shape Size Direction of muscle fibers Number of origins Location of attachments Action

Which muscle of mastication is the synergist of temporalis and masseter muscles in elevation of the mandibule?

Medial pterygoid

What is the coracobrachialls the synergist of?

Pectoralis major

What are the 3 functional groups of muscles?

Prime mover/agonist Antagonists Synergists

Give an example of a bipennate muscle.

Rectus femoris of the thigh

Which lever is being described -always operates at mechanical advantage -has strength -lacks speed and range of motion

Second class

What is a second class lever in the body? Where are the following Fulcrum Load Effort

Standing on tip toe -joint of the ball of the foot -weight of the body -calf muscles pulling upward

What are the 4 rotator cuff muscles?

Supraspinatus Infraspinatus Teres minor Subscapularis

What is the synergist of the latissimus dorsi?

Teres major: extends, medially rotates, and adducts arm

Location of the attachments: is the origin or insertion named first in "sternocleidomastoid"

The origin is always first

What is an example of a straplike parallel fascicle arrangement in a muscle?

The sartorius muscle of the thigh

*Which of the three lever systems involved in muscle mechanics would be the fastest lever?*

Third class

Which lever is being described -always operates at mechanical disadvantage -allows rapid movements with little shortening -tends to be thick and powerful

Third class

What muscle is the antagonist of forearm flexors?

Triceps brachii

True or False: Muscles with parallel fasicicle arrangments shorten most, but are not very powerful

True. The powerful muscles have the greatest number of fibers