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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]
Joints of the hand, X-ray Interphalangeal ligaments and phalanges. Right hand. Deep dissection. Posterior (dorsal) view. The PIP joint exhibits great lateral stability. Its transverse diameter is greater than its antero-posterior diameter and its thick collateral ligaments are tight in all positions during flexion, contrary to those in the metacarpophalangeal joint.
The dorsal venous network of the hand is a venous network on the dorsum (backside) of hand. It is formed by the dorsal metacarpal veins (three in number), a dorsal digital vein from the radial (lateral) side of the index finger and one from the ulnar (medial) side of the little finger, and both dorsal digital veins of the thumb.
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 dorsal branch of ulnar nerve arises about 5 cm. proximal to the wrist; it passes backward beneath the Flexor carpi ulnaris, perforates the deep fascia, and, running along the ulnar side of the back of the wrist and hand, divides into two dorsal digital branches; one supplies the ulnar side of the little finger; the other, the adjacent sides of the little and ring fingers.
An extensor expansion (extensor hood, [1] dorsal expansion, dorsal hood, dorsal aponeurosis [citation needed]) is the special connective attachments by which the extensor tendons insert into the phalanges. These flattened tendons (aponeurosis) of extensor muscles span the proximal and middle phalanges. [2]
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 dorsal branch of the ulnar nerve divides into two dorsal digital branches; one supplies the ulnar side of the little finger; the other, the adjacent sides of the little and ring fingers. It also sends a twig to join that given by the superficial branch of the radial nerve for the adjoining sides of the middle and ring fingers, and assists ...