What is the Third Metacarpal Bone
The third metacarpal (3rd metacarpal) is the bone associated with the middle finger, forming the palm of the human hand along with the other four metacarpals . It is the second longest metacarpal , and like the others, has a head, body or shaft, and base .
Where is it Located
It is located between the distal carpal row, and the third proximal phalanx, with the metacarpals of the index finger and ring finger located on its two sides .
Development and Ossification
Like the other metacarpals (apart from the thumb), this one also has an ossification center for its head and another for the shaft . The second and third metacarpals are the first to begin ossifying, with the ossification centers for their shaft starting to appear around the 8th-9th week of fetal growth. The head starts to ossify when a child is about 3 years old .
Anatomy of the Middle Finger Metacarpal: Surfaces and Joints
This metacarpal has multiple articular facets on its base, which is shaped somewhat like a styloid process with an articular facet on the radial-dorsal surface, for articulating with the distal carpal bone capitate. Apart from that, one articular facet on the medial surface communicates with the metacarpal of the index finger, and another facet on the medial side articulates with the fourth metacarpal .
At its distal end, the third metacarpal head articulates with the third proximal phalanx .
Common Injuries and Associated Conditions
Fracture and dislocation are among the common injuries of the third metacarpal, usually present with other hand bone injuries, occurring due to an accident . Arthritis of the third carpometacarpal joint is also relatively rare.