THE LIMBS OF THE HORSE 115 



that supply the biceps, semitendinosus, semimembranosus, superficial 

 gluteal, and coccygeus muscles. Branches also anastomose with the 

 obturator and deep femoral arteries. 



]Sr, GLUTEUS CRANiALis. — As will be seen in the dissection of the 

 pelvis, the cranial gluteal nerve arises by roots derived from the sixth 

 lumbar and first sacral nerves. As a single nerve-trunk it can scarcely 

 be said to exist, for it almost immediately divides into three, four, or 

 five branches, which the dissector of the gluteal region will find travers- 

 ing the greater sciatic foramen along with the cranial gluteal vessels 

 and the sciatic nerve. These branches supply the gluteal muscles, and 

 one runs between the middle and deep gluteal to end in the tensor of 

 the fascia lata. 



N. gluttEUS caudalis. — Of the two nerves that run backwards 

 (caudalwards) on the surface of the blended sacro-spinous and sacro- 

 tuberous ligaments, the more dorsal is the caudal gluteal. Its origin 

 from the sacral nerves will be revealed during the dissection of the 

 pelvis. At the present time the dissector has to note the exit of 

 the nerve from the greater sciatic foramen and its distribution in 

 the middle gluteal, piriformis, and biceps muscles. One of its branches 

 — to the superficial gluteal muscle — has been previously observed as it 

 bends round the border of the piriformis muscle. 



N. CUTANEUS FEMORis POSTERIOR. — The posterior cutaneous nerve 

 of the thigh leaves the pelvis by the greater sciatic foramen along with 

 the sciatic nerve, with which it is connected for a longer or shorter 

 distance. The nerve runs along the surface of the sacro-spinous and 

 sacro-tuberous ligaments in the direction of the sciatic arch. After 

 giving a communicating branch to the pudendal nerve it divides into 

 two branches. The more dorsal of these ends in the semitendinosus 

 muscle.^ The ventral branch is mainly cutaneous in its distribution. 

 After passing over the lateral aspect of the sciatic tuber it runs between 

 the biceps and semitendinosus muscles to gain the surface of the limb, 

 where it is distributed to the skin of the lateral and posterior part of 

 the thigh. 



N. iscHiADicus. — The sciatic nerve leaves the pelvis by the greater 

 sciatic foramen in jcompany with the gluteal nerves and vessels. As a 

 broad band of nerve fibres it passes backwards (caudalwards) obliquely 

 to the level of the hip joint, where it ends by dividing into two branches 

 of unequal size — the tibial and common peroneal nerves. The exact 

 point of division of the sciatic is variable, being occasionally so early 

 as to be close to the greater sciatic foramen. 



In its course the nerve lies in succession on the sacro-spinous 

 1 Some writers regard this branch as a part of the caudal gluteal nerve. 



