Palmar interossei muscles

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Palmar interossei muscles
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The Interossei volares of left hand.
Latin musculi interossei palmares
Gray's subject #126 465
Origin: metacarpals
Insertion: proximal phalange
Artery:
Nerve: deep branch of ulnar nerve
Action: adduction
Antagonist: Dorsal interossei of the hand
Dorlands/Elsevier m_22/12549407

The palmar interossei (interossei volares) are small muscles in the hand that lie on the anterior aspect of the metacarpals. They are smaller than the dorsal interossei of the hand, which lie between the metacarpals.

Structure

Each palmar interosseous muscle arises from the entire length of the metacarpal bone of one finger, and is inserted into the side of the base of the proximal phalanx and extensor expansion of the extensor digitorum tendon to the same finger.

There are three palmar interossei:

# Origin Insertion
first from the ulnar side of the second metacarpal bone into the same side of the proximal phalanx of the index finger
second from the radial side of the fourth metacarpal bone into the same side of the ring finger
third from the radial side of the fifth metacarpal bone into the same side of the little finger

The palmar interossei are unipennate.

From this account it may be seen that each finger is provided with two interossei, with the exception of the little finger, in which the abductor digiti minimi muscle takes the place of one of the pair.

Some texts consider the medial head of the flexor pollicis brevis to be a palmar interosseous muscle. This muscle would then be considered the first palmar interosseous muscle, and the total number of palmar interosseous muscles in the hand would be four.

Innervation

All of the interosseous muscles of the hand are innervated by the deep branch of the ulnar nerve.

Actions

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. The interossei also assist the lumbricals.

See also

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

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