Question | Answer |
zygomaticus major | O/zygomatic bone | I/skin at angle of mouth and orbicularis orbis |
masseter | O/maxilla and zygomatic arch | I/angle and ramus of mandible |
sternocleidomastoid | O/sternum and clavicle | I/mastoid process of temporal bone |
pectoralis major | O/clavicle, sternum, and costal cartilages of the second to sixth ribs | I/greater tubercle and lateral lip of the intertubular sulcus of humerus |
deltoid | O/acromial extremity of clavicle (anterior fibers), acromion of scapula (lateral fibers), and spine of scapula (posterior fibers) | I/deltoid tuberosity of humerus |
action of the zygomaticus major | draws angle of mouth superiorly and laterally, as in smiling |
action of the masseter | elevates mandible, as in closing mouth |
action of the sternocleidomastoid | acting together (bilaterally), flex cervical portion of vertebral column, flex head; acting singly (unilaterally), laterally extend and rotate head to side opposite contracting muscle |
action of the pectoralis major | as a whole, adducts and medially rotates arm at shoulder joint; clavicular head flexes arm |
action of the deltoid | lateral fibers abduct arm at shoulder joint; anterior fibers flex and medially rotate arm at shoulder joint; posterior fibers extend and laterally rotate arm at shoulder joint |
biceps brachii | O/long head: tubercle above glenoid cavity of scapula; short head: coracoid process of scapula | I/radial tuberosity of radius and bicipital aponeurosis |
action of the biceps brachii | flexes forearm at elbow joint, supinates forearm at radioulnar joints, and flexes arm at shoulder joint |
pronator teres | O/medial epicondyle of humerus and coronoid process of ulna | I/midlateral surface of radius |
action of the pronator teres | pronates forearm at radioulnar joints and weakly flexes forearm at elbow joint |
flexor carpi radialis | O/medial epicondyle of humerus | I/second and third metacarpals |
action of the flexor carpi radialis | flexes and abducts hand (radial deviation) at wrist joint |
psoas major | O/transverse processes and bodies of lubar vertebrae | I/with iliacus into lesser trochanter of femur |
action of the psoas major | psoas major and iliacus muscles acting together flex thigh at hip joint, rotate thigh laterally, and flex trunk on hip as in sitting up from supine position |
gluteus maximus | O/ileac crest, sacrum, coccyx, and aponeurosis of sacrospinalis | I/iliotibial crest of fascia lata and lateral part of linea aspera (gluteal tuberosity) under greater trochanter of femur |
action of the gluteus maximus | extends thigh at hip joint and laterally rotates thigh |
gluteus medius | O/ileum | I/greater trochanter of femur |
action of the gluteus medius | abducts thigh at hip joint and medially rotates thigh |
rectus femoris | [part of the quadriceps femoris] O/anterior inferior ileac spine | I/patella via quadriceps tendon and then tibial tuberosity via patellar ligament |
action of the rectus femoris | extends leg at knee joint; flexes thigh at hip joint |
semimembranosus | O/ischial tuberosity | I/medial condyle of tibia |
action of the semimembranosus | flexes leg at knee joint and extends thigh at hip joint |
gastrocnemius | O/lateral and medial condyles of femur and capsule of knee | I/calcaneus by way of calcaneal (Achilles) tendon |
action of the gastrocnemius | plantar flexes foot at ankle joint and flexes leg at knee joint |
belly | the fleshy portion of the muscle between the tendons |
origin | the attachment of a muscle's tendon to the stationary bone |
insertion | the attachment of a muscle's tendon to movable bone [the origin is usually proximal and the insertion is usually distal] |
prime mover, aka agonist | a muscle that causes a desired action |
antagonist | a muscle that relaxes as the agonist contracts; stretches and yields to the movement of the agonist |
synergists | muscles that contract and stabilize the intermediate joints when an agonist is acting on a joint that is multiple joints away from the agonist's origin [e.g., stabilizing wrist when certain muscles with origins high up the arm act on the fingers |
action of the frontalis (occipitofrontalis frontal belly) | raises eyebrow, wrinkles forehead |
action of the orbicularis orbis | closes and protrudes lips |
action of the orbicularis oculi | closes eye |
action of the temporalis | elevates mandible |
action of the rectus abdominis | compresses abdomen, flexes vertebral column |
action of the external oblique | unilaterally: rotates vertebral column || bilaterally: compress abdomen and flex verterbral column |
action of the erector spinae | extends vertebral column |
action of the diaphragm | increases size of thoracic cavity for inspiration |
action of the external intercostals | elevates ribs for inspiration |
action of the internal intercostals | depresses ribs for expiration |
action of the pectoralis major | pulls scapula anteriorly and downward |
action of the serratus anterior | pulls scapula anteriorly |
action of the trapezius | elevates, depresses, and adducts scapula || extends neck (moves head back) |
action of the latissimus dorsi | extends and adducts arm at shoulder; depresses shoulder |
action of the teres major | extends and adducts arm at shoulder |
action of the triceps brachii | extends forearm at elbow |
action of the supinator | supinates forearm |
action of the flexor digitorum superficialis | flexes fingers |
action of the extensor digitorum | extends fingers |
action of the extensor carpi ulnaris | extends and adducts wrist |
action of the iliacus | flexes hip, flexes vertebral column |
action of the adductor longus | flexes and adducts hip |
action of the gracilis | adducts hip, flexes knee |
action of the vastus lateralis | extends knee |
action of the vastus medialis | extends knee |
action of the vastus intermedius | extends knee |
action of the sartorius | flexes hip and knee; laterally rotates hip |
action of the biceps femoris | extends hip, flexes knee |
action of the semitendinosus | extends hip, flexes knee |
action of the tibialis anterior | dorsiflexion and inversion of foot at ankle |