THE HOCK JOINT 119 



whilst the other runs downwards and outwards to become inserted ' 

 into the outer aspect of the cuboid. The tendon of the extensor pedis 

 muscle crosses the anterior common ligament vertically a little to the 

 outer side of the median line. 



The tendon of the flexor perforans plays through the tarsal sheath 

 the synovial membrane of which lines the posterior face of the posterior 

 common ligament. It is therefore in close relationship to the tibio- 

 tarsal, intertarsal, and tarso-metatarsal articulations. The tendon or the 

 flexor perforatus is removed from the true hock joint, since it plays over 

 the summit of the tuber calcis. It is, however, in close relationship to 

 the calcaneo-metatarsal ligament at the back of the tuber, and a little 

 lower down is found immediately behind that of the flexor perforans. 

 The tendon of the gastrocnemius terminates at the hock, since it is 

 inserted in the depression at the summit of the tuber calcis. 



Running downwards and forwards over the outer aspect of the joint 

 is the tendon of the peroneus muscle, whilst on the inner aspect the 

 long, well-defined tendon of the flexor accessorius muscle runs down- 

 wards and slightly backwards. 



The Blood-vessels 



The anterior tibial artery, the larger of the two divisions of the 

 popliteal artery, is found on the deep surface of the flexor metatarsi 

 muscle. It passes downwards over the anterior face of the true hock 

 joint. It then deviates slightly outwards and passes beneath the cuboid 

 division of the tendon of the flexor metatarsi. Over the region of the 

 scaphoid the vessel terminates by dividing into the large metatarsal and 

 perforating metatarsal arteries. It gives ofi^ a number of small articular 

 branches. The perforating metatarsal artery passes right through the 

 hock from front to back in the canal formed between the cuboid, 

 scaphoid and cuneiform magnum, and then joins the two plantar arteries 

 to form the tarsal arch. From the .entrance to the cuboido-scaphoido- 



