138 



SKELETON OF THE PIG 



The occurrence of fifteen thoracic vertebra? appears to b(> quite common, and some observers 

 have recorded the existence of sixteen and even seventeen; a reduction to thirteen is rare. 



The lumbar vertebrae are six or seven in number. The iDodies are longer than 

 in the thoracic region and bear a ventral crest. They become wider and flatter 

 in the posterior part of the series. The arches are deeply notched, and are separated 

 by an increasing space dorsally. The mammillary processes project outward and 

 backward. The transverse processes are bent downward and incline a little for- 

 ward. Their length increases to the fifth and is much diminished in the last. They 

 form no articulation with each other or with the sacrum. The posterior edge of the 

 root of the process is marked by a notch in the anterior part of the series, a fora- 

 men in the posterior part. The spines 

 are broad and incline forward, with the 

 exception of the last, which is narrow 

 and vertical. 



Lesbre states that six and seven lumbar 

 vertebrae occur with almost equal frequency. 

 The number may be reduced to five, and the 

 munber of presacral vertebra? varies from 

 twenty-six to twenty-nine. 



The sacrum consists usually of four 

 vertebrae, which fuse later and less com- 

 pletely than in the other domesticated 

 animals. It is less curved than in the 

 ox. The spines are absent, excepting 

 small rudiments on the last two seg- 

 ments. The middle of the dorsal surface 

 is flattened and smooth, and presents 

 openings into the sacral canal between 

 adjacent arches (Spatia interarcualia) . On 

 either side are the superior sacral fora- 

 mina, and tubercles which indicate the 

 fused articular processes. The wings re- 

 semble those of the ox. The anterior 

 articular processes are very large. The 

 pelvic surface resembles that of the ox, 

 but is not so strongly curved, and the 

 transverse lines are very distinct. 

 The coccygeal vertebrae are specially characterized by the presence of func- 

 tional articular processes on the first four or five, beyond which these processes 

 become non-articular and smaller. The arches of the first five or six are complete. 

 The transverse processes are broad and plate-like in the anterior part of the series 

 and diminish very gradually. 



The numerical variation here is twenty to twenty-six according to the observation of several 

 anatomists. Lesbre states that he has found twenty-three most frequently. 



Curves. — The cervical region is practically straight. The thoracic and lumliar 

 regions form a gentle curve, concave ventrally, the highest point of which is at the 

 junction of the two regions. The sacral promontory is not so pronounced as in the 

 ox, and the sacral curve is flatter. 



Fig. 108. — Sacrum of Pig, Dorsal View. 

 a. Wing; b, dorsal sacral foramina; c, arfieular 

 process; I-4, segments or sacral vertebrae. (EUen- 

 berger-Baum, Anat. d. Haustiere.) 



The Ribs 



The ribs number fourteen or fifteen pairs, of which seven are sternal and seven 

 or eight asternal usually. They are in general strongly curved in the improved 



