Metacarpal bones are the five long bones that compose the skeleton of the palm of the hand. They are found between the root of the palm (made of carpal bones) and bones of the fingers (phalanges). This region of the hand that they comprise is often simply called the metacarpus.
Metacarpals are named with numbers 1-5, with metacarpal 1 being on the thumb side and metacarpal 5 being on the pinky finger side.
Unlike the phalanges, there is only one row of metacarpal bones, meaning that there is no division to proximal, middle or distal metacarpals. Metacarpal bones are analogous to the the metatarsal bones in the foot.
This article will describe the anatomy of the metacarpal bones.
|Metacarpal bones of the hand|
|Definition||Five long bones that compose the skeleton of the palm of the hand.|
|Nomenclature||Metacarpal bone 1 (thumb side)
Metacarpal bone 2 (index finger level)
Metacarpal bone 3 (middle finger level)
Metacarpal bone 4 (ring finger level)
Metacarpal bone 5 (pinky finger level)
|Parts||Base (proximal end)
Shaft (long central part)
Head (distal end)
Anatomy and structure
Metacarpals are long bones. Each of them features a base, a shaft and a head. The bases of metacarpals are their proximal ends, those closer to the root of the hand. With their bases, the metacarpals articulate with the carpal bones. The shaft is the central, long portion of the bone, while the head is the distal end of the bone, the one that articulates with proximal phalanges.
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All five metacarpals have a uniform structure with no specific anatomical landmarks on them. Some exceptions to note are:
- The first metacarpal (metacarpal of the thumb) is the thickest metacarpal bone
- The third metacarpal is distinguishable by the presence of a styloid process on the lateral surface of its base. This process enables more stable articulation between the carpal and metacarpal bones, enabling the hand skeleton to handle a lot of pressure and to perform delicate tasks.
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- Standring, S. (2021). Gray’s Anatomy (42tst ed.). Edinburgh: Elsevier Churchill Livingstone.