Muscular System

Rigid, moving structures (bones) that move on a fixed point (fulcrum) when muscles provide applied force to overcome a load; each joint is a fulcrum

The fixed point on which a lever moves; each joint acts as a fulcrum

Fixed point of attachment of a muscle to bone; usually proximal to insertion

Movable point of attachment of a muscle to bone

Movements produced by muscle contraction; described in terms of effect on bone or joint

Muscle mostly responsible for producing a particular movement

Muscle that opposes the movement of a particular agonist

A smaller muscle that assists a larger agonist

A stabilizing muscle that prevents movement at other joints

Agonists and antagonists work in pairs; when one contracts the other elongates (e.g., flexors-extensors, abductors-adductors)

Approximately 700

Muscles grouped based on location and function

Cranial nerve VII; originate on skull

Cranial nerve V; move the mandible

Cranial nerve XII; names end in glossus

Cranial nerve X; begin the swallowing process

Cranial nerves III, IV, and VI; originate on surface of orbit; control position of eyes

Control position of larynx, depress mandible, tense floor of mouth, support muscles of tongue and pharynx

Inferior rectus, medial rectus, superior rectus, lateral rectus, inferior oblique, superior oblique

Inferior rectus and superior rectus need to be remembered

Strongest jaw muscle

Helps elevate the mandible

Elevate, depress, and protract mandible; slide mandible side to side (lateral excursion)

Palatoglossus, styloglossus, genioglossus, hyoglossus; all named for origin and insertion

Extends from clavicle and sternum to mastoid; turns head obliquely to opposite side

Flex neck and elevate upper ribs

Spinal extension muscles

Semispinalis group, multifidus, interspinales, intertransversarii, rotatores

Spinal lateral flexor

Internal/ external obliques

Neck spinal flexors (deep neck flexors)

Thoracolumbar flexor between xiphoid process and pubic symphysis; divided longitudinally by linea alba

Aid in breathing movements of ribs

Wraps around waist for stabilization

Divides thoracic and abdominopelvic cavities; major muscle used in breathing

Support organs of pelvic cavity and control movement of materials through urethra and anus

Position and stabilize pectoral and pelvic girdles; move upper and lower limbs

Fan-shaped muscle on chest; originates along ribs, inserts on medial border of scapula

Originates on ribs, attaches to coracoid process of scapula

Upper elevates scapulae, middle retracts scapulae, lower depresses scapulae; originates from skull to spinous process of T12, inserts on scapula and clavicle

Deep to trapezius; attach to cervical and thoracic vertebrae, insert on medial border of each scapula

The major abductor of the arm

Assists deltoid

Produce medial rotation at shoulder

Produce lateral rotation at shoulder

Between anterior chest and greater tubercle of humerus; produces adduction and internal rotation at shoulder joint

Between thoracic vertebrae and humerus; produces extension, adduction, and internal rotation at shoulder joint

Muscles involved in shoulder rotation: supraspinatus, infraspinatus, teres minor, subscapularis

The major flexor of the elbow

Other elbow flexors

The major extensor of the elbow

Originate on scapula

Mainly on posterior and lateral surfaces of arm

Mainly on anterior and medial surfaces of arm

Originate on humerus and ulna; rotate radius

Originates on ulna; assists pronator teres in opposing actions of supinator or biceps brachii

Flexes and adducts wrist

Flexes and abducts wrist

Flexes wrist

Extends and abducts wrist

Extends and adducts wrist

Lie in forearm; only tendons cross wrist; provide strength and gross movement of hand and fingers

Originate on carpal and metacarpal bones; no muscles originate on phalanges; provide fine motor movement of the hand

Largest, most posterior gluteal muscle; produces extension and lateral rotation at hip

Works with gluteus maximus to pull on iliotibial tract of lateral surface of thigh

Originate anterior to gluteus maximus; insert on greater trochanter of femur

Group of six muscles, including the dominant piriformis

Produces hip adduction and flexion

Produce hip adduction

Produces adduction and extension

Two hip flexors that insert on the same tendon: psoas major and iliacus

Most originate on edges of pelvis; insert on tibia and fibula

Most originate on shaft of femur; insert on the patella

Biceps femoris, semitendinosus, semimembranosus

A knee flexor

Knee extensors consisting of three vastus muscles and rectus femoris

Gastrocnemius, soleus, fibularis muscles, tibialis posterior

Shared by the gastrocnemius and soleus

Extrinsic muscle producing flexion at ankle; opposes the gastrocnemius

Extrinsic muscles producing flexion at ankle

Extrinsic muscles producing flexion at toes

Originate on tarsal and metatarsal bones; move toes and maintain longitudinal arch of foot