Espiral AtlasMetacarpal bones
ossa metacarpi
Study entry
Parts
Five bones, numbered from the thumb (1st) to the little finger (5th); each with a base (proximal), shaft and head (distal, the "knuckles"). The 1st is the shortest and thickest; the 3rd has a styloid process at the base.
Joints
Carpometacarpal with the distal row of the carpus, intermetacarpal between the bases and metacarpophalangeal with the proximal phalanges.
Palpation
Dorsal surfaces and heads when the hand is closed.
Clinical
Fracture of the neck of the 5th metacarpal when throwing a punch ("boxer's fracture").
Source: cap. 3, «Huesos de la mano» y cuadro clínico
Clinical correlation
Fractures of the metacarpals; boxer's fracture
From the 2nd to the 5th, the metacarpals are attached to one another, so an isolated fracture is usually stable, and because they are well supplied with blood they heal quickly. An oblique (spiral) fracture may overlap or rotate the distal fragment, shortening the finger or making it flex out of alignment. Crushing may break several and leave the hand unstable. The fracture of the 5th metacarpal, the "boxer's fracture", happens when an untrained person throws a punch with a closed, abducted fist: the head rotates on the shaft and is left flexed.
Dermatoglyphics and single palmar crease
The patterns of the skin ridges of the palm (dermatoglyphics) help in examining people with certain congenital anomalies and genetic diseases. In trisomy 21 (Down syndrome) they are characteristic and a single transverse palmar crease is common; about 1% of the general population also has this crease, with nothing else of the syndrome.
Related clinical cases
- Fractures of the metacarpals; boxer's fracture
- Dermatoglyphics and single palmar crease