198 OSTEOLOGY. 
the figures in the position they occupy in the hand viewed from the front. The views 
on either side and above and below represent respectively the corresponding surfaces of 
the bone turned towards the spectator. 
Scaphoid Bone (0s naviculare).—This is the largest as well as the outermost 
bone of the first row. Its palmar surface, rough for the attachment of ligaments, 
é is irregularly triangular. 
Os MAGNUM SCAPHOID amy q . { as F << Byes f 
pre pen 1e inferior external 
TRAPEZIUM angle forms a projection 
. called the tuberosity; this 
can be felt at the base of 
eieheer corti the root of the thumb. Its 
radialis brevior superior surface 18 Gonvex 
xtensor carpi a Lies Ora} - A 
—pwalislongpr {rom side to side and be- 
I. Meracarrar, fore backwards for articu- 
ae lation with the radius. 
orsé A E 
interossei This area extends con- 
SEMILUNAR 
CUNEIFORM,. 
Extensor ossis 
PIsiFORM——, }/! i oils 
‘metacarpi pollicis. 
Extensor carpi 
ulnaris 
V. MeracarpaLt— ir q Y f) Mis o ~~ Hh A Sesamoip siderably over the pos- 
ee terior surface of the bone. 
Extensor 
brevis pollicis Its ainfervor surface 1s 
convex from before back- 
wards, and extends on to 
the dorsal aspect of the 
bone, shghtly convex from 
side to side; it 1s divisible 
into two areas, the outer 
for articulation with the 
trapezium, the inner for 
the trapezoid. The outer 
surface 1s narrow and 
wy 
iW longus 
f Dea 
W pollicis 
First 
PHALANX 
SECOND | y 
PHALANS | | rounded and forms a non- 
we ME articular border, which 
r : extends from the radial 
THIRD iW 
articular surface above 
_ Extensor communis to the tuberosity below. 
digitorum and extensor ,,, é . 
/ indicis The «inner surface 1s 
hollowed out in front 
for articulation with the 
head of the os magnum. 
Above this it displays < 
small semilunar-shaped 
facet for the semilunar 
bone. The dorsal non- 
articular surface lies he- 
Fic. 140,—THe Bones oF THE RIGHT WRIST AND HAND AS tween the radial articular 
SEEN FROM BEHIND. surface. above and the 
surface for the trapezium 
and trapezoid below. It is obliquely grooved for the attachment of the posterior 
ligaments of the wrist. The scaphoid articulates with five bones—the radius, the 
semilunar, the os magnum, the trapezoid, and the trapezium, 
Semilunar Bone (os lunatum).—So called from itsdeeply excavated form, the semi- 
lunar bone lies between the scaphoid on the outer side and the cuneiform on the inner. 
Its palmar surface, of rhombic form and considerable size, is rough for the attachment 
of ligaments; its superior surface, convex from side to side and from before back- 
wards, articulates with the radius and in part with the under surface of the 
triangular fibro-cartilage of the wrist. Its inferior aspect, deeply hollowed from 
before backwards, is divided into two articular areas, of which the outer is the 
larger; this is for the head of the os magnum; the inner, narrow from side to side, 
articulates with the unciform. Its eaternal surface, crescentic in shape, serves for 
PHALANX | @ 
i 
Bs 
