FOREARM
- The forearm is divided into two compartments
- A ventromedial or flexor compartment
- A dorsolateral or extensor compartment.
- Muscles of the forearm segregate into these compartments consisting of
- (1) An anterior group (the flexors of the wrist and fingers and the pronators)
- (2) A posterior group (the extensors of the wrist and fingers and the supinator)
- Muscles of anterior forearm
- Superficial – 4 muscles
- Intermediate – 1 muscle
- Deep- 3 muscles
- Superficial group – arises mostly from a common flexor tendon that attaches to the anterior part of the medial epicondyle of the humerus, and from adjacent fascia. These muscles are supplied chiefly by the median nerve
- Pronator teres (pierced by median nerve)
- Flexor carpi radialis
- Palmaris longus
- Flexor carpi ulnaris
- Intermediate muscle- arises from this common tendon and along the anterior surface of the ulna and radius and is also supplied by the median nerve.
- Flexor digitorum superficialis
- Deep group – is supplied mostly by a branch of the median nerve(the anterior interosseous nerve)
- Flexor pollicis longus
- Flexor digitorum profundus
- Pronator quadratus
NOTE
CLINICAL EDGE Volkmann’s ischemic contracture
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KEYNOTE
- Flexion at elbow- by all superficial muscles
- Flexion at wrist- flexor carpi radialis,flexor carpi ulnaris and Palmaris longus
- Flexion at finger – flexor digitorum superficialis and flexor digitorum profundus
- Pronation- pronator teres and pronator quadratus
MUSCLES OF THE POSTERIOR FOREARM
- Five superficial muscles
- Two intermediate muscles
- Five deep muscles
- Superficial group– arises mostly from the posterior aspect of the lateral epicondyle of the humerus by a common tendon. These muscles are supplied by Radial nerve or its deep branch, which continues as the posterior interosseous nerve.
- Brachioradialis (keeps hand in mid prone position)
- Extensor Carpi Radialis Longus
- Extensor Carpi Radialis Brevis
- Extensor Carpi Ulnaris– The insertion of the extensor carpi radialis brevis into the base of the third metacarpal is a common site for the development of a “ganglion“
- Anconeus (helps in screwing movement)
- Intermediate muscles
- Extensor digitorum
- Extensor digiti minimi
- Deep muscles
- Abductor Pollicis Longus
- Extensor Pollicis Longus
- Extensor Pollicis Brevis
- Extensor Indicis
- Supinator (pierced by radial nerve)
KEYNOTE:
- Muscles helping in supination- supinator, biceps brachii,brachioradialis
- Paralysis of extensor muscle leads to wrist drop + finger drop