The muscles in the hand are divided into intrinsic and extrinsic groups; however, the intrinsic muscles are contained entirely within the hand. There are four muscle groups comprising the intrinsic hand muscles: thenar, hypothenar, interossei, and lumbrical muscles [2, 3, 9, 1].
Intrinsic Hand Muscles: A Detailed Look
Here's a breakdown of the four intrinsic muscle groups of the hand:
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Thenar Muscles: These three muscles are located at the base of the thumb on the palm side (palmar aspect) and control thumb movements. The thenar muscle group is also known as the thenar eminence [2].
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Hypothenar Muscles: Found at the base of the little finger (pinky), these muscles control the movement of the little finger.
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Interossei Muscles: Located between the metacarpal bones, these muscles are responsible for finger abduction (moving fingers apart) and adduction (bringing fingers together).
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Lumbrical Muscles: These unique muscles originate from the tendons of the flexor digitorum profundus and assist in finger flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.
| Muscle Group | Location | Function |
|---|---|---|
| Thenar | Base of the thumb (palmar aspect) | Thumb movement |
| Hypothenar | Base of the little finger | Little finger movement |
| Interossei | Between metacarpal bones | Finger abduction and adduction |
| Lumbrical | Originate from flexor digitorum profundus | Finger flexion at metacarpophalangeal joints, extension at interphalangeal joints |
