BONES OF THE HIND LIMB 



203 



The inner and outer ridge each bears a projection distinguished as the 

 internal and external malleolus of the tibia. The former is very prominent, 

 so much so, sometimes, as to give the inner and upper part of the hock 

 an abnormal appearance. These projections afford attachment for strong- 

 connecting ligaments uniting the bones of the hock joint. 



The articular grooves, which they assist 

 in forming, take an oblique direction from 

 behind outward and forward. 



The Fibula (3, fig. 311) is a long slender 

 bone connected with the outer side of the 

 tibia, with the head of which it unites by 

 a small synovial articulation. It is broad 

 above and tapers downwards to the lower 

 third of the femur, where it terminates in a 

 pointed extremity. 



THE TARSUS OR HOCK 



This joint (fig. 312) is composed of six 

 bones, viz., the calcis, astragalus, cuboid, 

 cuneifoi'ni magnum, cuneiform medium, and 

 cuneiform parvum. 



The Calcis is situated at the posterior and 

 outer part of the hock, of which it forms the 

 " point ", and gives attachment to the tendons 

 of important muscles as well as to powerful 

 ligaments. It articulates in front with the 

 astragalus and below with the cuboid bone and 

 the cuneiform magnum, on which it rests. 



Astragalus or Knuckle -Bone. — This 



is the largest bone in the hock. It is placed 

 in front of the calcis, and from it project for- 

 ward two pulley -like ridges separated by a 

 deep groove. These ridges are received into 



two corresponding grooves already referred to as existing on the inferior 

 extremity of the tibia, and the central ridge on the last-named part fits 

 into the groove separating those on the astragalus. Together these two 

 bones form the true hock joint, to which the movements of flexion and 

 extension of the limb are for the most part due. The astragalus rests 

 upon the cuneiform magnum, with which it forms a flattened gliding-joint 

 of very limited movement. Behind, it articulates with the calcis. 



Fig. 311.— Tibia (Posterior Aspect) 



^ Spine of Tibia. - Articulation of 

 Fibula. 3 Fibula. •> External Malleolus. 

 ^ Internal Malleolus. ^ Shaft showing 

 Bony Ridges for Muscular Attachment. 



