![]() In a normal flexed hand, the fingertips should align and point towards the scaphoid tubercle on the radial volar aspect of the wrist. Physical examination of the hand may reveal deformities, decreased grip strength, and possible finger misalignment. Findings include pain (most intense over fracture site), edema, a shortened finger or finger deformity (such as depressed or missing knuckle), and bruising. At times, a crush mechanism is responsible. ![]() Metacarpal fractures usually occur after a fistfight, car accident, or fall. The looser attachments of the fourth and fifth metacarpals allow them to oppose the thumb. The second and third metacarpals are more rigidly fixed upon the corresponding carpal bones than the fourth and fifth metacarpals. The first metacarpal is shorter and wider than the other metacarpals and has a more extreme angulation with the carpus. The head of the metacarpal receives its own blood supply from the collateral ligaments this arrangement predisposes the head to possible avascular necrosis with a ligament injury, as the ligament injury may disrupt perfusion. The dorsum of the head accommodates the extensor tendons while the palmar surface has a ridge for the flexor tendons. The metacarpal head articulates with the proximal phalanx of each finger, with tubercles on each side providing attachment for the collateral ligaments. The metacarpal neck lies just proximal to the head, distal to the shaft. ![]() The extensor tendons lie atop the flat dorsum of the metacarpal shaft. This attachment, along with the extensor and flexor muscles crossing (but not attaching to the metacarpal), produces the main deforming force that may displace shaft fractures. ![]() The medial and lateral surfaces provide attachment for the interossei muscles. There is a medial, lateral, and dorsal surface on the metacarpal shaft. The body (or shaft) of the metacarpal is concave with respect to the palmar surface. The metacarpal base is cuboidal in shape, and ligaments provide articulations between the metacarpal bones and the carpus at the carpometacarpal (“CMC”) joint. Figure 1: The 5 metacarpal bones are shown in red. ![]()
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