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Palmar interossei muscles

Anatomy and supply

The palmar interossei are three muscles located in the metacarpus. They arise from the metacarpal bones of the index, ring and little finger. The origin surfaces of these muscles are facing towards the middle finger:

  • Palmar interosseous muscle I: ulnar side of the index finger
  • Palmar interosseous muscle II: radial side of the ring finger
  • Palmar interosseous muscle III: radial side of the little finger

From there, the muscles insert at the dorsal aponeurosis and the base of the proximal phalanx of their respective finger. The middle finger itself does not have its own palmar interosseous. The nerve supply is provided by the deep branch of the ulnar nerve (C8-Th1).


The most important function of the palmar interossei is the closing of spread fingers, which means the movement of the fingers towards the middle finger (adduction in the metacarpophalangeal joints [MCP]). In detail, the first pulls the index finger medially whereas the second and third pull the ring and little fingers laterally. Functionally, the palmar interossei act antagonistically to the dorsal interossei in the MCP (mnemonic: DAB = Dorsals ABduct, PAD = Palmars ADduct). However both muscle groups perform common functions, as they flex the fingers in the MCP and extend in the proximal and distal interphalangeal joints (PIP and DIP). An analogous muscle group can be found in the foot which fulfills identical movements in the toes (plantar interossei muscles).

An unexplored fourth muscle

Current literature assumes that there are three palmar interossei. Nevertheless, in 1858 the German anatomist Henle has described a fourth palmar interosseous between the thumb and the index finger (palmar interosseous of Henle). At first, it was assumed that the fibers he found were not an independent muscle, but instead part of either the adductor pollicis or flexor pollicis brevis. However, newest studies have shown that most people actually do have one additional short hand muscle between the thumb and the index finger. At this point, it is not clarified how this unknown muscle should be classified and which function it fulfills.

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Show references


  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2nd edition, Thieme Verlag (2007), p. 316-317
  • J. E. Muscolino: The muscular system manual – The skeletal muscles of the human body, 2nd edition, Elsevier Mosby (2005), p. 683-685
  • J. Witthaut/C. Leclercq: Der M. interosseus palmaris des Daumens, Handchirurgie Mikrochirurgie Plastische Chirurgie (1999), Thieme Verlag, Issue 21(1), p. 66-69
  • R. S. Susman/L. Nyati/ M. S. Jassal: Observations on the pollical palmar interosseous muscle (of Henle), The Anatomical Record (1999), Issue 254(2), p. 159-165


  • Achudhan Karunaharamoorthy


  • Palmar interossei muscles - Yousun Koh 
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Wrist and Hand
Wrist and Hand
The wrist is a joint area that connects the forearm to the hand and is mainly defined by the carpal bones. Let's look at the structures found in the wrist and hand.
  1. Bones of the wrist and hand
  2. Carpal bones
  3. Metacarpal bones
  4. Phalanges of the hand
  5. Muscles of the hand
  6. Neurovasculature of the hand
  7. Thenar muscles
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  8. Hypothenar muscles
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  9. Metacarpal muscles
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First look at bones and muscles
First look at bones and muscles
Before immersing in the vast amount of structures that you need to learn in anatomy, let’s start with the main bones and muscles found in the Human body.
  1. Main bones of the upper extremity
  2. Main bones of the lower extremity
  3. Main bones of the trunk
  4. Main bones of the head
  5. Main muscles of the upper extremity
  6. Main muscles of the lower extremity
  7. Main muscles of the trunk
  8. Main muscles of the head and neck

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