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A myotome is the group of muscles that a single spinal nerve innervates. [1] Similarly a dermatome is an area of skin that a single nerve innervates with sensory fibers. Myotomes are separated by myosepta (singular: myoseptum). [2] In vertebrate embryonic development, a myotome is the part of a somite that develops into muscle.
In human anatomy, the dorsal interossei (DI) are four muscles in the back of the hand that act to abduct (spread) the index, middle, and ring fingers away from the hand's midline (ray of middle finger) and assist in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints of the index, middle and ring fingers. [1]
It is an abductor of the little finger [1] at the metacarpophalangeal joint. [6] It is also possible that the muscle contributes to extension of the middle phalanx of the little finger through its connection to finger's extensor mechanism. [5] It plays an important role when the hand is grasping large objects with outspread fingers. [7]
The interosseous muscles of the hand are muscles found near the metacarpal bones that help to control the fingers. They are considered voluntary muscles. They are generally divided into two sets: 4 Dorsal interossei - Abduct the digits away from the 3rd digit (away from axial line) and are bipennate.
Abduction of the thumb is defined as the movement of the thumb anteriorly, a direction perpendicular to the palm. The abductor pollicis brevis does this by acting across both the carpometacarpal joint and the metacarpophalangeal joint. It also assists in opposition and extension of the thumb.
Wartenberg's sign is a neurological sign consisting of involuntary abduction of the fifth (little) finger, caused by unopposed action of the extensor digiti minimi. [ 1 ] [ 2 ] This commonly results from weakness of some of the ulnar nerve innervated intrinsic hand muscles -in particular the palmar interosseous muscle to the little finger ...
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 ...
The palmar interosseous muscles adduct the fingers towards the middle finger. This is in contrast to the dorsal interossei, which abduct the fingers away from the middle finger. In addition (like dorsal interossei) they flex the finger at the metacarpo-phalangeal joint and extend the finger at the interphalangeal joint and thus assist the ...