Palmar interossei

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Palmar interossei
Palmar interossei.gif
System: Muscle
Function: Adduction of the index finger, ring finger and little finger
Origin: Anterior shafts of index metacarpal, ring metacarpal and little metacarpal
Branches:
Insertion: proximal phalanges and extensor expansion of medial side of index finger and lateral side of ring finger and little finger
Arterial supply:
Venous drainage:
Lymphatic drainage:
Innervation: Deep terminal branch of the ulnar nerve (C8, T1
Vertebral levels:
Search for Interossei volares in Gray's.

The three palmar interossei (singular palmar interosseous, also called volar interossei, interossei volares) are short adductors of the fingers.

Contents

Shape

The palmar interossei are smaller than the corresponding dorsal interossei, and are situated on the anterior surface of the metacarpal bones rather than between them. There are three palmar interossei, the first affecting the index finger, the second the ring finger and the third the little finger. Each arises from the length of the anterior surface of its metacarpal, to insert into the proximal phalanx and extensor expansion of its finger.

First palmar interosseous

The first palmar interosseous arises from the medial side of the index metacarpal, inserting into the medial side of the proximal phalanx and extensor expansion of the index finger.

Second palmar interosseous

The second palmar interosseous arises from the lateral side of the ring metacarpal, inserting into the lateral side of the proximal phalanx and extensor expansion of the ring finger.

Third palmar interosseous

The third palmar interosseous arises from the lateral side of the little metacarpal, inserting into the lateral side of the proximal phalanx and extensor expansion of the little finger.

Actions

Joints Affected

Origin

First palmar interosseous:

Second palmar interosseous:

Third palmar interosseous:

Insertion

First palmar interosseous:

Second palmar interosseous:

Third palmar interosseous:

Nerve Supply

Flexor pollicis brevis and naming of the palmar interossei

The medial head of flexor pollicis brevis shares many similarities with the palmar interossei, such that it is sometimes described as the 'first palmar interosseous' (interosseous volaris primus). If this is so then the numbering of the other palmar interossei changes. Because of this the palmar interossei are sometimes referred to by name, eg 'index palmar interosseous'.

See Also

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