Carpal bones are positioned in the wrist which attaches the radius and ulna of the forearm among the metacarpal bones of the hand and is composed of eight individual carpal bones which are arranged in two rows.
Proximal row of carpal bones
The proximal row of carpal bones is lateral to the medial side are (i)scaphoid, (ii)lunate, (iii) triquetral (iv) pisiform bones.
The scaphoid is boat-shaped and holds a tubercle on its lateral side.
The lunate is half-moon-shaped.
The triquetral does pyramidal in shape and becomes an isolated oval facet on the distal portion of the palmar surface.
The pisiform is pea-shaped and becomes only one oval facet on the proximal portion of its dorsal surface.
In the proximal row, the scaphoid and lunate articulate with the radius to form the wrist joint.
Distal row of carpal bones
The distal row of carpal bones is lateral to the medial side are (i) trapezium, (ii) trapezoid, (iii) capitate (iv) hamate bones.
The trapezium is quadrangular in appearance and has a crest and a groove anteriorly. It has a concavo-convex articular surface distally.
The trapezoid matches the shoe of a baby.
The capitate is the biggest carpal bone, including a rounded head.
The hamate is wedge-shaped, including a hook near its base.
In the distal row, all of the carpal bones articulate with the metacarpals.
The most commonly injured carpal bone is the scaphoid bone, located near the base of your thumb.