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The muscles of the thumb are nine skeletal muscles located in the hand and forearm. The muscles allow for flexion , extension , adduction , abduction and opposition of the thumb . The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in the forearm, and the intrinsic hand ...
The abductor pollicis brevis is a flat, thin muscle located just under the skin. It is a thenar muscle, and therefore contributes to the bulk of the palm's thenar eminence. It originates from the flexor retinaculum of the hand, the tubercle of the scaphoid bone, and additionally sometimes from the tubercle of the trapezium.
Abductor pollicis brevis abducts the thumb. This muscle is the most superficial of the thenar group. Flexor pollicis brevis, which lies next to the abductor, will flex the thumb, curling it up in the palm. (The flexor pollicis longus, which is inserted into the distal phalanx of the thumb, is not considered part of the thenar eminence.)
The radial nerve innervates the finger extensors and the thumb abductor; that is, the muscles that extend at the wrist and metacarpophalangeal joints (knuckles) and abduct and extend the thumb. The median nerve innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, the first and second lumbricals. The ulnar ...
For patients with low median nerve palsy, it has been shown that the flexor digitorum superficialis of the long and ring fingers or the wrist extensors best approximate the force and motion that is required to restore full thumb opposition and strength. This type of transfer is the preferred method for median nerve palsy when both strength and ...
Ulnar neuropathy is a disorder involving the ulnar nerve. Ulnar neuropathy may be caused by entrapment of the ulnar nerve with resultant numbness and tingling. [3] It may also cause weakness or paralysis of the muscles supplied by the nerve. Ulnar neuropathy may affect the elbow as cubital tunnel syndrome.
The second, third, and fourth dorsal interossei have insertions both proximally on the base of the metacarpal and hood, and distally on the lateral bands and central tendon of the extensor mechanism. The abductor digiti minimi, effectively the "fifth dorsal interosseus" or the dorsal interosseus of the little finger, has only a proximal insertion.
The brachioradialis, flexor of the elbow, is unusual in that it is located in the posterior compartment, but it is actually a muscle of flexor / anterior compartment of the forearm. The anconeus , assisting in extension of the elbow joint, is by some considered part of the posterior compartment of the arm.