Muscles of forearm : Quick review

A) Superficial flexors:

Common flexor origin: Medial epicondyle

Nerve supply: Median nerve except Flexor carpi ulnaris which is also supplied by ulnar nerve

MuscleInsertionFunctionNerve Supply
Pronator teresMid-lateral radiusFlex forearmMedianĀ  nerve
Flexor carpi raialis2nd and 3rd metacarpal bonesFlex wristMedian nerve
Palmaris longusPalmar aponeurosisFlex wristMedian nerve
Flexor carpi ulnarisPisiformFlex wristMedian nerve and Ulnar nerve
Flexor digitorum superficialisBase of middle phalangesFlex Proximal Interphalangeal (PIP) jointMedian nerve

superficial flexors mnemonic

Mnemonic: Put your thenar/hypothenar eminence over medial epicondyle and fan out 5 fingers with thumb resting below the 4 fingers. Starting from the index finger count – “Pass, Fail, Pass, Fail, and Fail (at last)” i.e. PT, FCR, PL, FCU and FDS resectively.

B) Deep flexors

Nerve supply: Anterior interosseous branch of median nerve except Flexor digitorum profondus which is also supplied bu ulnar nerve

MuscleOriginInsertionFunction
Flexor Digitorum ProfundusAnterior and medial ulnarBase of distal phalangesFlex Distal Interphalangeal Joint (DIP)
Flexor Pollicis LongusAnterior and lateral radiusBase of distal phalange of thumbFlex Interphalangeal joint of thumb
Pronator QuadratusDistal ulnaVolar radiusPronation of hand

C) Superficial Externsors

Common extensor origin: Lateral epicondyle and supracondylar humerus

Nerve supply: Radial nerve

MuscleInsertionFunction
BrachioradialisLateral distal radiusExtend wrist
Extensor carpi radialis longus2nd Metacarpal baseExtend wrist
Extensor carpi radialis brachi3rd Metacarpal baseExtend wrist
AnconeusProximal dorsal ulnaExtend forearm
Extensor digitorumExtensor aponeurosisExtend digits
Extensor digitorum minimiiOriginates from common extensor tendon and inserts into little fingerExtend little finger
Extensor carpi ulnaris5th Metacarapal baseExtend/adduct hand

Brachioradialis is a paradoxical muscle. Its origin and innervation are characteristic of a extensor muscle, but it is actually a flexor at the elbow.

posterior compartment of forearm

D) Deep Extensors

Nerve supply: Radial nerve

MuscleOriginInsertionFunction
SupinatorLateral epicondyle of humerus, ulnaDorsolateral radiusSupination of hand
Abductor Pollicis LongusDorsal ulna/radius1st Metacarpal boneAbduction of thumb
Extensor Pollicis BrevisDorsal radiusBase of proximal phalanx of thumbMetacarpo-phalangeal (MCP) joint extension of thumb
Extensor Pollicis LongusDorsolateral ulnaBase of dorsal phalanx of thumbInterphalangeal joint extension of thumb
Extensor Indicis PropriusDorsolateral ulnaExtensor apparatus of index fingerExtension of index finger

Supinator has two heads, which the deep branch of the radial nerve passes between.

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