EXTENSOR MUSCLE OF FOREARM 

There are 12 muscle in Posterior aspect/compartment of Forearms. In this 12 muscle, 7 muscle is Superficial and 5 muscle is deep

a) Superficial muscle :-

There are 7 deep muscle in Posterior aspect/compartment of Forearm.

1) Anconeus

2) Brchioradialis

3) Extensor carpi redialis longus

5) Extensor carpi redialis brevis

6) Extensor carpi ulnaris

7) Extensor digiti minimi

8) Extensor digitorum

Deep Muscle of Forearm (left side)

ANCONEUS

ORIGIN: posterior surface of the lateral epicondyle

INSERTION: lateral surface of olecranon, body of ulna

ACTION: extension of forearm

NERVE SUPPLY : Radial Nerve 

BRACHIORADIALIS

ORIGIN: prox.2/3rd of lat.supracondylar ridge of humerus, lateral intermuscular septum

INSERTION: lateral aspect of distal radius just prox.to the styloid process

ACTION: acc. flexor of elbow

NERVE SUPPLY : Radial Nerve  (C5,C6)

EXT.CARPI RADIALIS LONGUS

ORIGIN: lateral supracondylar ridge of humerus

INSERTION: base of the 2nd MC bone

ACTION: extends and abducts the hand

NERVE SUPPLY : Radial nerve
(C6,C7)

EXTENSOR CARPI RADIALIS BREVIS

ORIGIN: lat.epicondyle of the humerus

INSERTION: base of the 3rd MC bone

ACTION: extends and abducts the wrist

NERVE SUPPLY : deep branch of radial .N(c7c8)

EXT.CARPI ULNARIS

ORIGIN: lateral epicondyle of humerus, Posterior border of ulna

INSERTION: medial side of the base of the 5th MC

ACTION: extends and adducts the hand

NERVE SUPPLY : Posterior interosseous Nerve  (C7,C8)

EXTENSOR DIGITI MINIMI

ORIGIN: lateral epicondyle of the humerus
 

INSERTION: extensor expansion of the 5th digit

ACTION: extention of 5th digit at MC, PIP ,extention of wrist when little finger in extension

NERVE SUPPLY : Posterior interosseous Nerve (C7, C8)

EXTENSOR DIGITORUM

ORIGIN: lateral epicondyle of the humerus

INSERTION: Extensor Expansions Of The Medial 4 digits

ACTION: extension at MCP, IP joints, ext of wrist when the fingers are extended

NERVE SUPPLY : Posterior interosseous Nerve (C7, C8)

b) Deep muscle :-

There are 5 deep muscle in Posterior aspect/compartment of Forearm

1) Supinator

2) Abductor policis longus

3) Extensor policies brevis

4) Extensor policies longus

5) Extensor indisis

(Attention :- First three muscle is make anatomical snuff box)

SUPINATOR

ORIGIN: lateral epicondyle of humerus, radial collateral lig. annular lig.,supinator fossa, crest of ulna

INSERTION: lateral,posterior,anterior surface of prox 1/ 3rd 0f radius

 

ACTION: supination

NERVE SUPPLY : deep Branch Of
Radial Nerve  (C5,C6)

ABDUCTOR POLLICIS LONGUS

ORIGIN: upper parts of the posterior surface of the radius & ulna and interosseous mem.

INSERTION: base of the 1st MC bone

ACTION: abducts,extends, lat.rotat
es the thumb at carpometacarpal joint, & abducts the wrist.

NERVE SUPPLY : Posterior interosseous Nerve (C7, C8)

EXTENSOR POLLICIS BREVIS

ORIGIN: posterior surface of the radius below the origin of Abductor Pollicis longusand from interosseous mem.

INSERTION: base of the prox.phalanx of the thumb

ACTION: extends pox.phalanx of the thumb at MC joint, ext.at 1st carpometacarpal joint

NERVE SUPPLY : Posterior interosseous Nerve (C7, C8)

 

EXT.POLLICIS LONGUS

ORIGIN: posterior surface of middle 1/3rd of ulna And interrosseous mem.

INSERTION: base of the diastal phalanx of the thumb

ACTION: extends distal phalanx of the thumb at MP joint, IP joint.and it can contribute abduction of the thumb

NERVE SUPPLY : Posterior interosseous Nerve (C7, C8)

EXTENSOR INDICIS

ORIGIN: posterior surface of
ulna 1/3rd below the EPL

INSERTION: extensor
expansion of the 2nd finger

ACTION: ext of index finger and wrist.

NERVE SUPPLY : Posterior interosseius nerve