Muscles of forearm and hand

brachioradialis

origin: proximal 2/3 of lateral supracondylar ridge of humerus

insertion: distal radius, lateral side just above styloid process

actions: flexes forearm

innervation: radial nerve (C6)

extensor carpi radialis longus

origin: distal 1/3 of lateral supracondylar ridge of humerus

insertion: base of 2nd metacarpal

actions: extends and abducts hand at wrist

innervation: radial nerve (C6,7)

extensor carpi radialis brevis

origin: lateral epicondyle of humerus

insertion: base of 3rd metacarpal

actions: extends hand, weak abduction of hand

innervation: deep radial nerve

extensor digitorum

origin: lateral epicondyle of humerus

insertion: via 4 tendons to bases of middle and distal phalanges of digits 2-5 (forms extensor expansion)

actions: extends digits 2-5 at metacarpophalangeal & interphalangeal joints, extends hand

innervation: posterior interosseous nerve

extensor digiti minimi

origin: lateral epicondyle of humerus

insertion: extensor expansion of 5th digit

actions: extends 5th digit; weak abductor of 5th digit

innervation: posterior interosseous nerve

extensor carpi ulnaris

origin: lateral epicondyle of humerus and posterior border of ulna

insertion: base of 5th metaarpal

actions: extends and adducts hand

innervation: posterior interosseous nerve

supinator

origin: lateral epicondyle of humerus, capsule of elbow joint, and supinator crest of ulna’

insertion: proximal third of radius-posterior, lateral, and anterior sides

actions: supinates forearm

innervation: deep radial nerve (C6)

abductor policis longus

origin: middle third of forearm- posterior ulna, interosseous membrane & radius

insertion: base of 1st metacarpal

actions: abducts thumb, abducts hand, extends thumb at carpometacarpal joint

innervation: posterior interosseous nerve

extensor policis brevis

origin: distal third dorsal radius & interosseous membrane

insertion: base of proximal phalanx of thumb

actions: extends proximal phalanx of thumb at metacarpophalangeal joint

innervation: posterior interosseous nerve

extensor policis longus

origin: middle third dorsal ulna & interosseous membrane

insertion: base of distal phalanx of thumb

actions: extends distal phalanx of thumb

innervation: posterior interosseous nerve

extensor indicis

origin: distal third, dorsal ulna & interosseous membrane

insertion: extensor expansion of index finger (digit 2)

action: extends index finger at metacarpophalangeal joint and interphalangeal joints

innervation: posterior interosseous nerve

pronator teres

origin: humeral head= medial epicondyle of humerus. ulnar head=coronoid process of ulna

insertion: lateral side of mid-radius

actions: pronates forearm, some flexion of forearm

innervation: median nerve (C7)

flexor carpi radialis

origin: medial epicondyle of humerus

insertion: base of 2nd metacarpal

actions: flexes, abducts hand at wrist

innervation: median nerve (C7)

palmaris longus

origin: medial epicondyle of humerus

insertion: palmar aponeurosis

actions: tightens palmar aponeusrosis; flexion of hand at wrist

innervation: median nerve (C7,8)

flexor carpi ulnaris

origin: humeral head= medial epicondyle of humerus. ulnar head= olecranon & proximal half of posterior ulna

insertion: base of 5th metacarpal, hook of hamate

actions: flexion and adduction of hand

innervation: ulnar nerve (C8)

flexor digitorum superficialis

origin: humeroulnar head= medial epicondyle of humerus & coronoid process of ulna. radial head= oblique line of radius

insertion: via 4 tendons to palmar aspect of shafts of middle phalanges, digits 2-5

actions: flexes middle & proximal phalanges of digits 2-5; flexes hand at wrist

innervation: medial nerve (C8)

flexor pollicis longus

origin: middle half of anterior radius & interosseous radius

insertion: base of distal phalanx of thumb (digit 1)

actions: flexes distal & proximal phalanges of thumb; flexes 1st metacarpal, flexes hand at wrist

innervation: anterior interosseous nerve

flexor digitorum profundus

origin: proximal ¾ of anterior-medial ulna, interosseous membrane

insertion: via 4 tendons to base of distal phalanges of digits 2-5

actions: flexes distal, middle & proximal phalanges of digits 2-5, flexes hand at wrist

innervation: medial 1/2= ulnar nerve (C8). lateral 1/2= anterior interosseous nerve

pronator quadratus

origin: distal ¼ of anterior ulna

insertion: distal ¼ of anterior radius

actions: pronates forearm

innervation: anterior interosseous nerve

abductor pollicis brevis

origin: lateral flexor retinaculum; trapezium; scaphoid

insertion: base of proximal phalanx of thumb

actions: abducts thumb

innervation: recurrent median nerce (C8)

flexor pollicis brevis

origin: lateral flexor retinaculum; trapezium; scaphoid

insertion: base of proximal phalanx of thumb

actions: flexes metacarpophalalngeal joint of thumb

innervation: recurrent median nerve (C8)

opponens pollicis

origin: lateral flexor retinaculum; trapezium; scaphoid

insertion: body of 1st metacarpal

actions: abducts, flexes, and medially medially rotates 1st metacarpal

innervation: recurrent median nerce (C8)

abductor digiti minimi

origin: medial flexor retinaculum; pisiform

insertion: base of proximal phalanx of 5th digit

actions: abducts 5th digit

innervation: deep ulnar nerve (T1)

flexor digiti minimi

origin: medial flexor retinaculum; hook of hamate

insertion: base of proximal phalanx of 5th digit

actions: flexes metacarpophalangeal joint of 5th digit

innervation:deep ulnar nerve (T1)

opponens digiti minimi

origin: medial flexor retinaculum, hook of hamate

insertion: body of 5th metacarpal

actions: flexes and rotates 5th metaarpal

innervation:deep ulnar nerve (T1)

adductor pollicis

origin: oblique head= trapezium;trapezoid; capitate; bases of 2nd and 3rd metacarpals. transverse head= anterior surface of 3rd metacarpal

insertion: base of proximal phalanx of thumb

actions: adducts thumb at carpometacarpal and metacarpophalangeal joints

innervation: deep ulnar nerve (T1)

lumbricals (4)

origin: tendons of flexor digitorum profundus

insertion: extensor expansions of digits 2-5

actions: flex metacarpophalangeal joint and extend interphalangeal joints of digits 2-5

innervation: median nerve (lateral 2 muscles), deep ulnar nerve (medial 2 muscles)

palmar interossei (3)

origin: palmar surface of metacarpals 2,4,5’

insertion: base of proximal phalanx & extensor expansion of digits 2,4,5

actions: addicts digits 2,4,5; via extensor expansion; assist lumbricals with flexing metacarpophalangeal joint and extending interphalangeal joints

innervation: deep ulnar nerve (T1)

dorsal interossei (4)

origin: sides of adjacent metacarpals, 1-5

insertion: base of proximal phalanx abd extensor expansion of digits 2,3,4

actions: abduct digits 2-4, via extensor expansion: assist lumbricals with flexing metacarpophalangeal joint and extending interphalangeal joints

innervation: deep ulnar nerve (T1)