E1E Flashcards
posterior compartment of the forearm
extensor retinaculum
- thickening of deep fascia of forearm that stretches across back of wrist holds long extensor tendons in position and prevents them from bowstringing as they cross wrist joint
- converts grooves on posterior aspects of distal ends of radius and ulna into 6 separate compartments (tunnels) for long extensor tendons (surrounded by synovial sheaths)
superficial muscle of the posterior compartment of the forearm
brachioradialis extensor carpi radialis longus extensor carpi radialis brevis extensor digitorum extensor digiti minimi extensor carpi ulnaris anconeus
brachioradialis origin
upper part of lateral supracondylar ridge of humerus
brachioradialis insertion
lateral side of distal end of radius, just superior to styloid process
brachioradialis innervation
radial nerve
brachioradialis action
flexion of forearm at elbow joint and assists with supination of forearm
extensor carpi radialis longus origin
lower part of lateral supracondylar ridge of humerus
extensor carpi radialis longus insertion
tendon passes under extensor retinaculum and inserts into base of 2nd metacarpal
extensor carpi radialis longus innervation
radial nerve
extensor carpi radialis longus action
extension and abduction of hand at wrist joint
extensor carpi radialis brevis origin
ommon extensor tendon (attached to lateral epicondyle of humerus)
extensor carpi radialis brevis insertion
tendon passes under extensor retinaculum and inserts into base of 3rd metacarpal
extensor carpi radialis brevis innervation
deep branch of radial nerve
extensor carpi radialis brevis action
extension and abduction of hand at wrist joint
extensor digitorum origin
common extensor tendon (attached to lateral epicondyle of humerus)
extensor digitorum insertion
- muscle belly gives rise to 4 tendons (for medial 4 digits)
- tendons pass under extensor retinaculum and fan out over dorsum of hand, where adjacent tendons are interconnected
- near proximal interphalangeal joint, each tendon divides into 3 bands
- central band inserts into base of middle phalanx and 2 lateral bands converge to insert into base of distal phalanx
extensor digitorum innervation
deep branch of radial nerve
extensor digitorum action
extension of distal, middle and proximal phalanges of medial 4 digits
extension of hand at wrist joint
extensor expansion (extensor hood, dorsal digital expansion)
- each tendon of extensor digitorum is held in a central position over dorsum of corresponding metacarpophalangeal (MCP) joint by a flat fibrous sheet called extensor expansion
- extensor expansion wraps around dorsum and sides of metacarpal head and proximal phalanx and forms movable hood that moves distally when MCP joint is flexed and proximally when MCP joint is extended
- tendons of interosseous and lumbrical muscles of hand insert into extensor expansions
extensor digiti minimi origin
common extensor tendon (attached to lateral epicondyle of humerus)
extensor digiti minimi insertion
tendon passes under extensor retinaculum and joins tendon of extensor digitorum for little finger
extensor digiti minimi innervation
deep branch of radial nerve
extensor digiti minimi action
extension of distal, middle and proximal phalanges of little finger and assists with extension of hand at wrist joint
extensor carpi ulnaris origin
humeral head: common extensor tendon (attached to lateral epicondyle of humerus)
ulnar head: posterior border of shaft of ulna
extensor carpi ulnaris insertion
tendon passes under extensor retinaculum and inserts into base of 5th metacarpal
extensor carpi ulnaris innervation
deep branch of radial nerve
extensor carpi ulnaris action
extension and adduction of hand at wrist joint