Muscles of Posterior Compartment Flashcards
Brachioradialis
Insertion
Lateral surface of distal end of radius of promixal to styloid process
Brachioradialis
Origin
Proximal two thirds of lateral supraepicondylar ridge of humerus
Brachioradialis
Innervation
Radial Nerve (C5, C6, C7)
Brachioradialis
Actions
Relatively weak flexion of elbow joint, maximal when forearm is in midpronated position
Extensor Carpi Radialis Longus
Origin
Lateral supra-epicondylar ride of humerus
Extensor carpi radialis longus
Insertion
Dorsal aspect of base of 2nd metacarpal
Extensor Carpi Radialis Longus
Innervation
Radial nerve (C6, C7)
Extensor Carpi Radialis Longus
Actions
Extend and abduct wrist joint
Extensor carpi radialis brevis active during fist clenching
Extensor carpi radialis brevis
Lateral epicondyle of humerus (common extensor origin)
Extensor carpi radialis brevis
Insertion
Dorsal aspect of base of 3rd metacarpal
Extensor carpi radialis brevis
Innervation
Deep branch of radial nerve (C7, C8)
Extensor carpi radialis brevis
Actions
Extend and abduct wrist joint
Extensor carpi radialis brevis active during fist clenching
Extensor Digitorum
Origin
Lateral epicondyle of humerus (common extensor origin)
Extensor Digitorum
Insertion
Extensor expansions of medial four fingers
Extensor Digitorum
Innervation
Posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve
Extensor Digitorum
Actions
Extend wrist joint
Extend medial four fingers primarily at metacarpophalangeal joints
Secondarily at interphalangeal joints
Extensor Digiti Minimi
Origin
Lateral epicondyle of humerus (common extensor origin)
Extensor Digiti Minimi
Insertion
Extensor expansion of 5th finger
Extensor Digiti Minimi
Innervation
Posterior interosseous nerve (C7, C8) continuation of deep branch of radial nerve
Extensor Digiti Minimi
Actions
Extends wrist joint
Extends 5th finger primarily at metacarpophalangeal joint, secondarily at interphalangeal joint
Extensor Carpi Ulnaris
Origin
Lateral epicondyle of humerus
Posterior border of ulna via a shared aponeurosis
Extensor Carpi Ulnaris
Insertion
Dorsal aspect of base of 5th metacarpal
Extensor Carpi Ulnaris
Innervation
Posterior interosseous nerve (C7,C8), continuation of deep branch of radial nerve
Extensor Carpi Ulnaris
Actions
Extends and adducts wrist joint (also active during fist flenching)
Supinator
Origin
Lateral epicondyle of humerus, radial collateral and anular ligaments, supinator fossa, crest of ulna
Supinator
Insertion
Lateral, posterior, and anterior surfaces of proximal third of radius
Supinator
Innervation
Deep branch of radial nerve (C7,C8)
Supinator
Actions
Supinates forearm
Rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
Abductor pollicis longus
Origin
Posteiror surface of proximal halves of ulna, radius, and interosseous membrane
Abductor pollicis longus
Insertion
Base of 1st metacarpal
Abductor pollicis longus
Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Abductor pollicis longus
Actions
Extends wrist joint
Abducts thumb and extends it at carpometacarpal joint
Extensor pollicis longus
Origin
Posterior surface of middle third of ulna and interosseous membrane
Extensor pollicis longus
Insertion
Dorsal aspect of base of distal phalanx of thumb
Extensor pollicis longus
Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor pollicis longus
Actions
Extends wrist joint
Extends distal phalanx of thumb at interphalangeal joint
Extends metacarpophalangeal and carpometacarpal joints
Extensor pollicis brevis
Origin
Posterior surface of distal third of radius and interosseous membrane
Extensor pollicis brevis
Insertion
Dorsal aspect of base of proximal phalanx of thumb
Extensor pollicis brevis
Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor pollicis brevis
Actions
Extends wrist joint
Extends proximal phalanx of thumb at metacarpophalangeal joint
Extends carpometacarpal joint
Extensor Indicis
Origin
Posterior surface of distal third of ulna and interosseous membrane
Extensor indicis
Insertion
Extensor expansion of 2nd finger
Extensor Indicis
Innervation
Posterior interosseous nerve (C7, C8), continuation of deep branch of radial nerve
Extensor Indicis
Actions
Extends wrist joint
Extends 2nd finger (enabling its independent extension)
Helps extend hand at wrist