Palmar Interossei Muscles – Origins & Function – Human Anatomy | Kenhub

Palmar Interossei Muscles – Origins & Function – Human Anatomy | Kenhub


Hey there! It’s Matt from Kenhub, and in
this tutorial, we will discuss the palmar interossei muscles. The palmar interossei
muscles are three unipennate muscles located in the metacarpus. They arise from the metacarpal
bones of the index, ring, and little fingers or fingers 2, 4 and 5 respectively. The surfaces of origin of all three of these
muscles face towards the middle finger and are located on the shaft of the finger they
act on, fingers 2, 4 and 5 to be exact. For example, as you can see here on the palmar
interosseus muscle 1 highlighted in green on this first image, it has its origin on
the ulnar side of the second metacarpal. Even though the palmar interosseus muscle 2 has
its origin on the radial side of the fourth metacarpal and the palmar interosseus muscle
3 has its origin on the radial side of the fifth metacarpal bone, both their muscle bellies
face the middle finger, as you can see on the images. The muscles insert at the dorsal aponeurosis
and the base of the proximal phalanx of their respective finger. Note that the middle finger
itself does not have its own palmar interosseus muscle. The nerve supply to these muscles
is provided by the deep branch of the ulnar nerve. The most important function of the palmar
interossei muscles is the closing of spread fingers, which means the movement of the fingers
towards the middle finger. In other words, the contraction of the palmar interossei muscles
results in the adduction of the little finger, ring finger and index finger toward the middle
finger. Other functions include flexion of the metacarpophalangeal joint and the extension
of the interphalangeal joint on those same fingers. Functionally, the palmar interossei act antagonistically
to the dorsal interossei in the MCP. There is a mnemonic that can help you remember this.
DAB equals Dorsals ABduct. PAD equals Palmar ADduct. However, both muscle groups perform
common functions as they flex the fingers in the metacarpophalangeal joints and extending
the proximal and distal interphalangeal joints. This video is more fun than reading a textbook,
right? If you want more videos, interactive quizzes, articles, and an atlas of human anatomy,
click on the “Take me to Kenhub” button. It is time to say goodbye to your old textbooks
and say hello to your new anatomy learning partner, Kenhub! See you there! https://www.kenhub.com

12 Replies to “Palmar Interossei Muscles – Origins & Function – Human Anatomy | Kenhub”

  1. Excellent Video. Good graphics and explanatinon.

    I would like to add that there are "usually" 4 palmar interosseous (PI). As high as 90 % of population have interossei originating from thumb MC. (Pollical palmar interossei muscle -PPIM)

    Some anatomist consider it as a part of adductor pollicis. One thing is for sure nobody will penalise students for mentioning that there are only 3 PI

    Thank you

    Dr. Sharad Singhai

    Reference: 
    1- And then there were four: Anatomical observations on the pollical palmar interosseous muscle in humans.
    Morrison PE1, Hill RV.

    2- "Pollical palmar interosseous muscle" (musculus adductor pollicis accessorius): attachments, innervation, variations, phylogeny, and implications for human evolution and medicine.

  2. 🙂 I would like to thank you for all useful tutorials
    !!but I noticed that in the figures there is no palmar interossei muscle in the thumb

  3. Hi guys! Hope you enjoyed watching our video on the palmar interossei muscles. Please let us know what you would like us to cover on the next videos! Are you ready to test your knowledge? Check out our quiz about the muscles of the hand available to premium members: https://khub.me/4tal1 Good luck!

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