VERTEBRAL COLUMN J 187 
The last three have accessory processes also. The first three or four spinous proc- 
esses are about equal inlength. Behind this they become gradually shorter to the 
tenth, and then remain equal. The backward slope is most marked in the ninth 
and tenth. The eleventh is practically vertical (anticlinal vertebra), and the last 
two incline slightly forward. 
The bodies of the seven lumbarvertebre are decidedly flattened dorso-ventrally, 
and increase in width from first to last. The length increases to the sixth. The 
transverse processes are plate-like and are directed forward and downward. Their 
length increases to the fifth and sixth. They form no joints with each other or 
with the sacrum. Their extremities are enlarged, with the exception of the last. 
The accessory processes project backward over the posterior notches of the first 
five. The anterior articular processes are large, compressed laterally, and bear 
mammillary processes. The spinous processes are broad below, narrower above, 
and with the exception of the last, incline a little forward. Their height diminishes 
behind the fourth. . 
The sacrum results from the early fusion of three vertebree. It is short, 
Fic. 206.—Firra Lumpar VERTEBRA OF Doc; Dorsat View. Fic. 207.—Sacrum oF Doc; VenTRAL View. 
1, Anterior end of body; 2, spinous process; 3, 3’, artic- I, II, IIT, Bodies of vertebrx; 1, 2, ventral saec- 
ular processes; 4, transverse process; 5, accessory process; ral foramina; 3, 4, linew transverse; 5, anterior end 
6, groove for spinal nerve. of body of first sacral vertebra; 6, 6’, anterior artic- 
ular processes; 7, 7’, wings; 8, posterior end of body 
of last sacral vertebra; 9, 9’, posterior articular proc- 
esses; 10, sacral canal; 11, spinous [process; 12, 
12’, transverse processes; 13, auricular surface. 
wide, and quadrangular. The spines are fused to form a median crest, which is 
notched, however, between the summits of the spines. On either side are two 
tubercles, vestiges of the fused articular processes. The pelvic surface is deeply 
concave and presents two pairs of foramina. The wings are prismatic and very 
high. Their lateral surfaces are extensive, face almost directly outward, and bear 
an auricular surface on the lower part. The anterior surface of the body of the 
first vertebra is extensive, depressed in its middle, and bears a prominent lip below. 
The anterior articular processes are large and have extensive, slightly concave 
facets which face dorso-medially. The posterior articular processes are small. 
The transverse processes of the last vertebra project backward and may articulate 
or fuse with those of the first coccygeal. The sacral canal is strongly compressed 
dorso-ventrally. 
The coccygeal vertebre are fully developed in the anterior part of the region. 
The arch is complete in the first six usually. The first three or four have well de- 
veloped articular processes at each end. Behind this the posterior processes 
quickly disappear, and the anterior ones become non-articular and gradually re- 
