BONES OF THE PELVIC LIMB 



155 



The patella is long, narrow, and very thick. The free surface is strongly con- 

 vex and very rough and irregular. The articular surface is convex from side to 

 side and nearly straight in the vertical direction. The large prominence on the 

 medial side for the attachment of the fibro-cartilage allows prompt determination 

 of the side to which the bone belongs. The apex is more pointed than in the horse. 

 The tarsus consists of five pieces; the central and fourth and the second and 

 third tarsal bones are fused. 



The tibial tarsal bone is relatively long and narrow, and is somewhat flattened 

 from before backward. It bears a trochlea at either end. The groove and ridges 

 of the proximal trochlea are not spiral, but almost sagittal; the lateral ridge is the 

 wider, and articulates with both tibia and fibula. The distal trochlea consists 

 of two condyles divided by a groove, and articulates with the 

 combined central and fourth tarsals. The plantar surface bears 

 a large oval facet for articulation with the fibular tarsal; this 

 occupies most of the surface, and is convex and grooved from 

 above downward. The lateral surface presents two facets for 

 articulation with the fibular tarsal, and is excavated and rough 

 elsewhere. The medial surface bears a tuberosity at its upper 

 part, and is flattened below. 



The fibular tarsal bone is longer and more slender than in 

 the horse. The distal part of the body is compressed laterally, 

 and bears a projection in front which articulates with the lateral 

 malleolus. The tuber calcis is marked posteriorly by a wide 

 shallow groove, which is coated with cartilage in the fresh state. 

 The central and fourth tarsals are fused to form a large 

 bone (Os centrotarsale quartum, scapho-cuboid) , which extends 

 across the entire width of the tarsus and articulates with all of 

 the other bones. The greater part of the proximal surface is 

 molded on the chstal trochlea of the tibial tarsal, and its medial 

 part rises high above the rest posteriorly. Laterally there is a 

 narrow, undulating surface for articulation mth the distal end 

 of the fibular tarsal bone. The plantar surface bears two tuber- 

 osities, of which the lateral one is rounded, the medial more 

 prominent and narrower. 



The first tarsal bone is quadrilateral and small. It articu- 

 lates with the central above, the metatarsus below, and the 

 second tarsal in front. 



The second and third tarsals are fused to form a rhomboid 

 piece The proximal surface is concavo-convex, and articulates 

 with the central component. The distal surface is undulating 

 and rests on the metatarsus. The lateral surface bears a small 

 facet in front for the fourth tarsal component, and the plantar 

 surface a very small one for the first tarsal bone. ,, +v. 



The large metatarsal bone is about one-seventh (ca. 3 cm.) longer than the 

 corresponding metacarpal. Its shaft is <^oinwessedtr^ns.e.se^^n^^^^ 

 four-sided: The groove on the dorsal surface is deep and wide The plantar 

 surf ace is marked by variable grooves. The proximal foramen on this surface does 

 not perforate the shaft, but passes obliquely through the extremity, opening on the 

 posterior part of its pUmal surface. The medio-plantar angle of the proximal 

 end bears a facet for articulation with the small metatarsal bone. 



The small metatarsal bone is a quadrilateral disc a little less than an inch m 

 width and height. Its anterior face bears a facet for articulation with the large 

 metatarsal bone. 



Fig. 



160. — L A R G E 



Metatarsal Bone 



OF Ox; Dorsal 



View. 



1, Vascular groove; 

 2, foramen; 3, 3', con- 

 dyles. 



