First palmar interosseous muscle - MRI hand - Axial - e-Anatomy
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First palmar interosseous muscle

Musculus interosseus palmaris primus

  • Related terms: Palmar interossei (1)

Definition

Muhammad A. Javaid

First palmar interosseous muscle

Origin

From the medial side of the palmar surface of the second metacarpal bone (index finger)

Insertion

Proximal phalanx and extensor hood (extensor expansion) of the 2nd digit (index finger)

nnervation

Deep branch of the ulnar nerve (C8, T1)

Action

Adduction of hand

The first palmar interosseous muscle is located in the second metacarpal space. It arises from the ulnar side of the second metacarpal bone. Its tendon inserts into the ulnar side of the base of the proximal phalanx of the index finger and its extensor hood, enabling adduction of the index finger towards the middle finger.

The palmar interossei also assist in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints via their insertion into the extensor expansion.

References

  • Valenzuela M, Bordoni B. Anatomy, Shoulder and Upper Limb, Hand Palmar Interosseous Muscle. [Updated 2025 Apr 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537165/

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