| Palmar interossei muscles | |
|---|---|
| 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 |
| Actions | adduction |
| Antagonist | Dorsal interossei of the hand |
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.
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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 dorsla interossei (abduction).
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.
All of the interosseous muscles of the hand are innervated by the deep branch of the ulnar nerve.
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 lumbricals.[1]
Mnemonic to remember action: PAD DAB Palmar - adduct, Dorsal Interossei - Abduct
It is currently accepted that more than 80% of individuals present a pollical palmar interosseous muscle (of the thumb) as suggested by Henle's description in 1858 and verified by numerous investigations such as those carried out by Randall S. Susman, Lukhanyo Nyati, and Mandeep S. Jassal.[2]
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