es. x , . be ll 
a THE CARPUS. 199 
=e 
articulation with the scaphoid, and also for the attachment of the interosseous 
ligaments which connect it with that bone. Its inner surface, of quadrilateral 
form, is cartilage-covered for 
articulation with the cuneiform, 
and the edge which separates this 
from the superior surface has 
attached to it the interosseous 
ligament which unites these two 
bones. The rough dorsal non- 
articular surface is much smaller 
than the palmar; by this means 
the front and back of the bone can 
readily be determined. The semi- 
lunar articulates with five bones 
—the scaphoid, the radius, the 
cuneiform, the unciform, and the 
os Magnum. 
Cuneiform or Pyramidal Bone 
(os triquetrum).—This bone may 
be recognised by the small oval 
or circular facet on its anterior 
surface for the pisiform. This is 
placed towards the lower part of the palmar surface, which is elsewhere rough for 
ligaments. The bone is placed obliquely, so that its surfaces cannot be accurately 
described as inferior, superior, etc.; but for convenience of description, the method 
already adopted is adhered to. The superior surface has a convex rhombic surface 
for articulation with the under 
surface of the triangular fibro- 
cartilage in adduction of the 
hand, though ordinarily it does 
{ 0s magnum not appear to be in contact with 
) that structure. To the ulnar 
side of this it is rough for 
ligaments. The inferior surface 
is elongated and concayo-convex 
from without inwards; here the 
bone articulates with the unci- 
form. The eaternal surface, 
broader in front than behind, 
Rading @tticulates with the semilunar. 
Scaphoid The inner surface, rounded and 
rough, is confluent above and 
behind with the superior and 
dorsal aspects of the bone. The 
dorsal surface, rounded and 
smooth externally, is ridged and 
Fra. 142.—Tae RIGHT SEMILUNAR BONE, grooved internally for the atitach- 
ment of ligaments. The cunei- 
form articulates with three bones, viz. the pisiform, the unciform, and the semilunar. 
The pisiform bone (0s pisiforme), about the size and shape of a large pea, rests 
on the anterior surface of the fore end of the cuneiform, with which it articulates 
by an oval or circular facet on its dorsal aspect. The rounded mass of the rest of 
the bone is non-articular, and inclines downwards and outwards so as to overhang the 
articular facet in front and externally. The mass of the bone is usually separated 
from the articular surface by a small but distinct groove. Into the summit of the 
bone the tendon of the flexor carpi ulnaris muscle is inserted, and here also the 
anterior annular ligament is attached. 
Trapezium (os multangulum majus).—The trapezium is the outermost boneof the 
second row of the carpus. It may be readily recognised by the oval saddle-shaped 
77\ Trapeziun 
al 
Semilunar 
Fig. 141.—THE RIGHT ScAPHOID BONE. 
Unciform 
Cuneiform _———— 
Unciform / 
Radius 
N/ 
