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The muscles of the hand are innervated by the radial, median, and ulnar nerves. 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.
Thus, the flexor muscle is used to aid the lumbrical muscles in their role as extensors of the interphalangeal joints. As the lumbrical muscles originate on the palmar side of the hand and attach on the dorsal aponeurosis, power is transferred from the flexor digitorum profundus muscle to fully extend the fingers as well as flex the ...
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 lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints, [1] and extend the interphalangeal joints. [ 1 ] [ 2 ] The lumbrical muscles of the foot also have a similar action, though they are of less clinical concern.
The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand.
In anatomy, flexor is a muscle that contracts to perform flexion (from the Latin verb flectere, to bend), [1] a movement that decreases the angle between the bones converging at a joint. For example, one's elbow joint flexes when one brings their hand closer to the shoulder, thus decreasing the angle between the upper arm and the forearm.
It tends to separate the fingers as it extends them. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint. Extension of the proximal and distal interphalangeal joints, however, is mediated predominantly by the dorsal and palmar interossei and lumbricals of the hand.
Fingers do not contain muscles (other than arrector pili). The muscles that move the finger joints are in the palm and forearm. The long tendons that deliver motion from the forearm muscles may be observed to move under the skin at the wrist and on the back of the hand. Muscles of the fingers can be subdivided into extrinsic and intrinsic muscles.