154 



SKELETON OF THE OX 



The shaft is distinctly curved, so that the medial side is convex. The posterior 

 surface is not divided into two areas, and the lineae musculares are fewer and extend 

 up higher than in the horse. The articular grooves and ridge of the distal end are 

 almost sagittal in direction, and present an extensive but shallow synovial fossa. 

 The lateral groove is sepal'rated by a sharp ridge from an outer area which is for 

 articulation with the lateral malleolus. The anterior part of the medial malle- 

 olus is prolonged downward and has a pointed end. The groove behind it is broad 

 and well defined. Laterally there is a deep narrow groove which separates two 

 prominences. The proximal extremity fuses with the shaft at three and one-half 

 to four years, the distal at two to two and one-half years. 



Tuber calcis 



M. m. 



Tuber 

 calcis 



M.l. 



Mi. 2 



ML 3+4 



Mt.3+4. 



Fig. 15S. — Right Tarsus axd Adjacent Boxe; 

 Medial \'iew. 



OF Ox; 



Fig. 1.59. — Right Tarsus and Adjacent Bones of 



Ox; DORSO-LATERAL ViEW. 



M. Til., Medial malleolus; M. L, lateral malleolus (distal end of fibula) ; T, tibia; T. t., tibial tarsal bone; T.f., fibular 

 tarsal bone (sustentaculum); T. c.-\-4, fused central and fourth tarsal bones; T. 1, first tarsal bone; T. 2-\-3, fused 

 second and tbird tarsal bones; ^It. 2, small or second metatarsal bone; Mt. 5-}- 4, large metatarsal or fused third and 

 fourth metatarsal bones ; /, groove for tendon of flexor digitalis longus ; ^, groove for deep flexor tendon. 



The fibula usually consists of the two extremities only. The head is fused with 

 the lateral condyle of the tibia and is continued by a small, blunt-pointecl prolonga- 

 tion below. The distal end remains separate and forms the lateral malleolus (some- 

 times called the os malleolare) . It is quadrilateral in outline and compressed from 

 side to side. The proximal surface articulates with the distal end of the tibia, and 

 bears a small spine which fits into the groove on that bone. The distal surface 

 rests on the fibular tarsal, and the medial articulates with the lateral ridge of the 

 tibial tarsal bone. The lateral surface is rough and irregular. 



The early cartilaginous fibula is complete, but later the shaft is reduced to the 

 small prolongation noted in speaking of the head and a fibrous cord which connects 

 it with the distal end (lateral malleolus). In some cases, however, the upper part 

 undergoes partial ossification, forming a slender rod which is usually united with 

 the lateral border of the tibia and is joined to the head by fibrous tissue. 



