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The first dorsal interosseous muscle is larger than the others. Between its two heads, the radial artery passes from the back of the hand into the palm. Between the heads of dorsal interossei two, three, and four, a perforating branch from the deep palmar arch is transmitted.
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.
The intrinsic muscle groups are the thenar and hypothenar (little finger) muscles; the interossei muscles (four dorsally and three volarly) originating between the metacarpal bones; and the lumbrical muscles arising from the deep flexor (and which are special because they have no bony origin) to insert on the dorsal extensor hood mechanism.
The thenar eminence refers to the group of muscles on the palm at the base of the thumb. The three muscles composing the thenar eminence are the abductor pollicis brevis, flexor pollicis brevis and opponens pollicis. [5] The other two muscles that influences movement of the thumb are the adductor pollicis and the first dorsal interosseous muscle.
All dorsal interossei are innervated by the lateral plantar nerve (S2–3). Those in the fourth interosseous space are innervated by the superficial branch and the other by the deep branch. [1] The first and second dorsal interossei muscles additionally receive innervation from the lateral branch of the deep fibular nerve. [4]
This occurs because the ulnar nerve also innervates the palmar and dorsal interossei of the hand. Patients with this deficit will become increasingly easy to identify over time as the paralysed first dorsal interosseous muscle atrophies, leaving a prominent hollowing between the thumb and forefinger.
Anatomically, the abductor pollicis brevis and first dorsal interosseous muscle are more wasted than the abductor digiti minimi. [1] If lesions affecting the branches of the ulnar nerve that run to the wasted muscles are excluded, the lesion is almost sure to be located in the anterior horn of the spinal cord at the C8-T1 level. [2]
Three dorsal forearm muscles act on the thumb: The abductor pollicis longus (APL) originates on the dorsal sides of both the ulna and the radius, and from the interosseous membrane. Passing through the first tendon compartment, it inserts to the base of the first metacarpal bone. A part of the tendon reaches the trapezium, while another fuses ...