VERTEBRAL COLUMN 



129 



irregular, and often bear projections of variable size and form The first is the 

 shortest and the length increases to the fifth, the last being considerably shorter 

 ihe spinous processes are relatively low and wide, the last being the smallest- 

 their summits are moderately thickened. ' 



The sacrum is longer than that of the horse. It consists originally of five 

 segments, but fusion is more complete and involves the spinous processes, which 

 are umted to form a median sacral crest (Crista sacralis media), with a convex 

 thick and rough margin. A lateral sacral crest is formed by the fusion of the ar- 

 ticular processes. The pelvic surface is concave in both directions, and is marked 

 by a central groove (Sulcus vasculosus), which indicates the course of the middle 

 sacral artery. The ventral sacral foramina are large. The wings curve downward 

 and forward; they are quad- 

 rangular, short, compressed 

 from before backward, and 

 high dorso-ventrally. They 

 have an extensive anterior 

 surface, which is concave 

 from side to side and non- 

 articular. The posterior sur- 

 face is rough, and at its lower 

 part there is a triangular area 

 for articulation with the 

 ilium. The body of the first 

 segment is very wide, and the 

 entrance to the sacral canal 

 correspondingly wide and 

 low. The anterior articular 

 processes are large and 

 widely separated; they are 

 concave and semicylindrical 

 in curvature medially . The 

 lateral borders are thin, 

 sharp, and irregular. The 

 bone does not become nar- 

 rower posteriorly, so that the 

 apex is usually a little wider 

 than the part just behind the 

 wings; the posterior end of 

 the median crest forms a 

 pointed projection over the 

 opening of the sacral canal. 



The coccygeal vertebrae 

 are longer and better devel- 

 oped than in the horse. The first five or six have complete arches and spinous 

 processes. The transverse processes are relatively large in the anterior part of 

 the series, in which there are also anterior articular processes (which do not articu- 

 late), and a pair of ventral spines which form a groove (Sulcus vasculosus) for the 

 middle coccygeal artery. 



Vertebral Curves. — The cervical curve is very slight and is concave dorsally. 

 The thoracic and lumbar regions form a gentle curve, concave ventrally. The 

 promontory is more pronounced than in the horse, especially in subjects in which 

 the sacrum is inclined upward behind. Another prominence occurs at the junction 

 of the sacrum and first coccygeal vertebrae. 



Length. — The following table gives the lengths (inclusive of the inter- 

 9 



Fig. 126. — Sackum of Ox; Ventral View. 

 I-V, Segments; 1^, ventral sacral foramina; 5, anterior end of body 

 of first sacral vertebra; 6, vascular groove; 7, posterior end of body of 

 last sacral vertebra. 



