180 



SKELETON OF THE PIG 



Four metacarpal bones are present. The first is absent, the third and fourth 

 are large and carry the chief digits, while the second and fifth are much smaller and 

 bear the accessory digits. Their proximal ends articulate with each other and with 

 the carpus as indicated above. The distal ends fuse with the shafts at about two 

 years of age. 



The third and fourth metacarpals are flattened from before backward, three-sided, and 

 placed close together. The distal end of each bears a trochlea for articulation with the first 

 phalanx and the sesamoids. The third is the wider of the two, and articulates with all of the distal 

 row of the carpus except the first. The fourth articulates with the fourth carpal chiefly, but has a 

 small facet for the third. The second and fifth metacarpals are placed further back than the chief 

 bones. The fifth is considerably the thicker of the two. The proximal ends are small and articu- 

 late with the corresponding carpal and metacarpal bones. The distal end is relatively large; its 

 articular surface is condyloid in front, trochlear behind. 



Each chief digit comprises three phalanges and three sesamoids. The bones 

 of the chief digits resemble those of the ox in form, but there is no foramen on the 

 interdigital side of the extensor process and the proximal sesamoids are narrow and 

 ridged behind. The phalanges of the accessory digits (which do not reach the 

 ground ordinarily) are similar in form but much smaller. Fusion of the proximal 

 ends with the shafts takes place at about two years for the first phalanges, at about 

 one year for the second phalanges. 



Crest of ilium 



y 



Gluteal line 



Tuber sncrale 



Lesser sciatic 

 notch 



Tuber 

 ischii 



Tuber coxtje 



Ilium {shaft) 



Acetabulum Ischium 



Fig. 191. — Left Os Cox.e of Pig; L.^ter.^l View. 



Tuber sacrale 



Crest of ilium 



Tuber 

 ischii 



Obturator \ IHo-pectineal 



foramen \ eminence 



Pubis (acetab- 

 ular branch) 



Fig. 192. — Left Os Cox.b of Pig; Medial View, 



BONES OF THE PELVIC LIMB 



The OS coxae is long and narrow. The ilium and ischium are almost in line 

 with each other and nearly sagittal in direction. The wing of the ilium bends out- 

 ward much less than in the horse or ox. The gluteal surface is divided into two fossae 



