22 ANTHROPOLOGY. 
8. SPECIAL ANATOMY OF THE SPINE. 
A, Bones of the Trunk. 
The trunk is constituted by the vertebral column or spine, the thorax, 
and the pelvis. 
The spine, columna vertebralis, rachis (pl. 122, fig. 3°, 4%*, fig. 5, A, B, C), 
is placed at the posterior part of the trunk, and consists of twenty-eight or 
twenty-nine pieces. Of these, twenty-four are called true vertebree, and 
connected by ligaments so as to form one strong but flexible column. The 
twenty-fifth piece, reckoning from the head, is the sacrum, and is inserted 
between the ossa innominata; the remaining three or four constitute the 
os coccyx, and in their imperfect form represent the caudal vertebree or tail 
of other vertebrate animals. | 
Each vertebra consists of a body, and of several projections or processes. 
The body occupies the anterior central part; it is thick and spongy, and 
rather circular or oval; its upper and lower surfaces are flat or slightly 
concave, and give attachment to the inter-vertebral ligaments. The mar- 
gin of each is tipped with a compact white substance, and the lower surface 
is rather larger than the upper. Anteriorly it is transversely convex and 
grooved horizontally, particularly on either side, and is likewise very 
porous. Posteriorly it is concave, so as to form part of the spinal canal or 
foramen. ‘This surface is perforated by large foramina for the escape of the 
venous canals which ramify through the bone. The processes of each ver- 
tebra are nine, two lateral or the lamine, two transverse, four oblique or 
articulating, and one spinous. | 
The lateral processes, or lamin, arise one on each side, by a sort of pedicle, 
from the posterior part of the body; they pass backwards, bounding the 
sides of the spinal hole, and unite posteriorly in the spinous process; they 
are broad behind, but narrow where they join the body, being grooved out 
above and below into a notch. The inferior of these is the larger. The 
Jaminze form the lateral and posterior portions of the spinal arch or forameft 
for the spinal cord. The roots of these lamine, or the pedicles, are con- 
sidered by some as separate portions; they form the common point of 
support for the other processes, and separate the superior. from the inferior 
notch. These notches, where the vertebrae are joined, form the inter-ver- 
tebral holes for the passage of the spinal nerves. 
The spinous process is the most projecting part of the vertebra in the 
posterior median line ; its base is bifurcated, and passes into the two lamine; 
its apex generally ends in a point or tubercle. The whole series of these 
processes presents the longitudinal prominent crest posteriorly, named spone. 
Each process receives the insertion of tendons, and serves as a lever for the 
extensor muscles of the column. 
The transverse processes arise from the roots of the lamine, or rather 
from the pedicles, and are directed outwards on each side; they serve for 
the attachment of tendons, and in the dorsal region they also support the 
ribs. 
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