The Wrist Joint - Computational Biomechanics of the Wrist Joint - page 5

Table 1.1 Description on the different structures of the eight carpal bones

Bone Description

Scophoid The scaphoid can be divided into three main regions: the proximal pole,

the waist and the distal pole. Several characteristics of the scaphoid have
been identified, which include a single convex distal surface for
articulation with the trapezium and trapezoid, a large concave distal
capitate surface, a flat semilunar lunate surface medially and a large
convex radial articular area extending dorsally [ 8 ]

The next bone wedged between the scaphoid and triquetrum with its
crescent shape is the lunate. This bone articulates laterally with the
scaphoid via its flat semilunar facet. The medial part, on the other hand
articulates with the triquetrum through its square surface. The radius, on
its proximal region is articulated via convex facet. Distally, its convex
surface articulates with the capitate

Lunate

Triquetrum The most medial bone of the proximal row carpal bone is the triquetrum.

This small and irregularly shaped bone has distal concavo-convex surface
which articulates with the hamate. At the anterior side of the bone, its
oval convex palmar facet articulates with the pisiform whilst radially, the
lunate is articulated with a square surface of the triquetrum

The sesamoid bone of the tendon of the flexor carpi ulnaris, which is the
pisiform has a single flat oval articular facet. This facet allows
articulation with the triquetrum on its dorsal surface [ 10 ]

Pisiform

Hamate The wedge shape bone, hamate has articular surfaces for the capitate and

triquetrum on either sides. For articulation with the fifth and fourth
metacarpals, there is a ridge at the distal articular surface, functions as a
divider between medial and lateral facets. A hook on its palmar side, also
known as hamulus, functions as an attachment point for certain
ligaments. This criterion gives the hamate its distinct shape [ 8 ]

Capitate The largest carpus namely the capitate which lies in the center of the

wrist has a convex surface of its proximal part which is articulated with
the lunate. Meanwhile, its lateral surface articulates with the trapezoid
and scaphoid, and medial surface with the hamate. A concave distal strip
on its lateral part is for articulation with the second metacarpal base
whilst the third metacarpal base was articulated via a concavo-convex
distal facet. The name of capitate is derived from the Latin word
'capitãtus' which means 'containing head' due to a rounded head-shaped
on its surface

(continued)