Chapter 10 Muscles of the upper limb

triceps brachii

A. D- large fleshy muscle; the only muscle of posterior compartment of arm A- powerful forearm extesor; antagonist of forearm flexors; elbow extensor

pronator teres and pronator quadratus

B and C two muscles that pronate the hand

biceps brachii

B. D- two-headed fusiform muscle; bellies unite as insertion point is approached A- flexes and supinates forearm; weak flexor of arm at shoulder; flexes the forearm and supinates the hand

brachialis

C. D- strong muscle that is immediately deep to biceps brachii on distal humerus A- a major forearm flexor; no role in supination

extensor digitorum

D- lies medial to extensor carpi radialis brevis A- prime mover of finger extension; extends hand; can abduct fingers; extends wrist and digits

extensor carpi radialis longus

D- parallels brachioradialis on lateral forearm and may bend with it A- extends hand in conjunction with extensor carpi ulnaris and abducts hand in conjunction with flexor carpi radialis; extends and abducts the wrist

pronator teres

D. D- two- headed muscle; seen in superficial view between proximal margins of brachioradialis and flexor carpi radialis A- pronates forearm; weak flexor of elbow

brachioradialis

E. D- superficial muscle of lateral forearm; forms lateral boundary of cubital fossa; extends from distal humerus to distal forearm A- synergist in flexing forearm; acts to best advantage when forearm is partially flexed and semipronated; stabilizes elbow during rapid flexion and extension

supinator

F. D- deep muscle at posterior aspect of elbow; largely concealed by superficial muscles A- assists biceps brachii to forcibily supinate forearm; works alone in slow supination; antagonist of pronator muscles

flexor carpi radialis

G. D- runs diagonally across forearm A- powerful flexor and abductor of hand; weak synergist of elbow flexion; power wrist flexor and abductor

palmaris longus

H. D- small fleshy muscle with a long insertion tendon A-flexion of the hand at the wrist.

flexor carpi ulnaris

I. D- most medial muscle of this group A- powerful flexor and adductor of hand in synergy with extensor carpi ulnaris; stabilizes wrist during finger extension

flexor digitorum superficialis

J. D- two-headed muscle; more deeply placed; overlain by muscles above but visible at distal end of forearm A- flexes wrist and middle phalanges of second to fifth fingers; the important finger flexor for speed and flexion against resistance; flexes wrist and middle phalanges

flexor pollicis longus

K. D- partly covered by flexor digitorum superficialis A- flexes distal phalanx of thumb

pronator quadratus

L. D- deepest muscle of distal forearm; passes downward and laterally; only muscle that arises solely from ulna and inserts solely into radius A- prime mover of forearm pronation; acts with pronator teres; also helps hold ulna and radius together

biceps brachii and supinator

two muscles that places the palm upward