Editing Carpal bones (section)

===Bones===
The eight carpal bones may be conceptually organized as either two transverse rows, or three longitudinal columns.

When considered as paired rows, each row forms an arch which is convex proximally and concave distally. On the palmar side, the carpus is concave and forms the [[carpal tunnel]], which is covered by the [[Flexor retinaculum of the hand|flexor retinaculum]].<ref name="Platzer-124">Platzer 2004, p 124</ref> The proximal row comprises the [[scaphoid bone|scaphoid]], [[lunate bone|lunate]], [[triquetral bone|triquetral]], and [[Pisiform bone|pisiform bones]] which articulate with the surfaces of the radius and distal carpal row, and thus constantly adapts to these mobile surfaces. Within the proximal row, each carpal bone has slight independent mobility.  For example, the scaphoid contributes to midcarpal stability by articulating distally with the trapezium and the trapezoid. In contrast, the distal row is more rigid as its transverse arch moves with the [[Metacarpal bones|metacarpals]].<ref name="Schmidt-29">Schmidt-Lanz 2003, p 29</ref>

[[Biomechanics|Biomechanically]] and clinically, the carpal bones are better conceptualized as three longitudinal columns:<ref name="Thieme-Atlas-224">''Thieme Atlas of Anatomy'' 2006, p 224</ref>
# Radial scaphoid column: scaphoid, trapezium, and trapezoid
# Lunate column: lunate and capitate
# Ulnar triquetral column: triquetrum and hamate
In this context the pisiform is regarded as a [[sesamoid bone]] embedded in the tendon of the [[Flexor carpi ulnaris muscle|flexor carpi ulnaris]].<ref name="Thieme-Atlas-224" /> The ulnar column leaves a gap between the ulna and the triquetrum, and therefore, only the radial or scaphoid and central or capitate columns articulate with the radius. The wrist is more stable in flexion than in extension more because of the strength of various capsules and ligaments than the interlocking parts of the skeleton.<ref name="Schmidt-29" />

Almost all carpals (except the pisiform) have six surfaces. Of these the ''palmar'' or ''anterior'' and the ''dorsal'' or ''posterior surfaces'' are rough, for ligamentous attachment; the dorsal surfaces being the broader, except in the lunate.

The ''superior'' or ''proximal,'' and ''inferior'' or ''distal surfaces'' are articular, the superior generally convex, the inferior concave; the ''medial'' and ''lateral surfaces'' are also articular where they are in contact with contiguous bones, otherwise they are rough and tuberculated.

The structure in all is similar: [[cancellous]] tissue enclosed in a layer of [[compact bone]].