272 OUTLINES OF EQUINE ANATOMY. 



the operation of neurotomy. To expose it, only skin, 

 fascliia, and aponeurosis of triceps abductor fenioris re- 

 quire to be divided. The posterior tibial nerve, dipping 

 between the internal head of gastrocnemius externus and 

 gastrocnemius internus, follows the course of its corre- 

 sponding artery over the back of the stifle-joint, and run- 

 ning down the posterior surface of the femur between the 

 gastrocnemius and perforans, just above the hock, divides 

 to form the external and internal metatarsal nerves, which, 

 after passing with the perforans tendon over tlie inner 

 surface of os calcis, separate and take a course, and give off 

 branches exactly as the metacarpal nerves do in the fore limb. 



In the space just above the heads of the gastrocnemii 

 muscles lie the popliteal lymphatic glands. It will thus 

 be seen that the hind limb below the hock very closely 

 resembles the fore limb below the knee ; besides the differ- 

 ences between the pedal and the cannon bones of the fore 

 and hind limb, the hoofs differ, those of the hind limb being 

 smaller, more upright, and having their ground surface 

 much longer than broad, and more concave, with thicker 

 soles than those of the fore. 



The coccygeal muscles I'equire a passing notice. 



Levator coccygis arises from the lateral part of the 

 sacrum between the superior spinous and transverse pro- 

 cesses, blending anteriorly with longissimus dorsi. It 

 passes backwarcls, and its several fasciculi become attached 

 to the rudimentary transverse processes of the coccygeal 

 vertebrae. It is covered by a layer of faschia. 



Curvator coccygis arises from the postero-lateral and 

 inferior part of the sacrum, and its fibres and fasciculi run 

 along the lateral part of the tail ; they are separated from 

 levator coccygis anteriorly by faschia. 



Compressor coccygis is a broad square muscle, which 

 extends from the inner surface of the sacro- sciatic ligament 

 to the transverse processes of the two or three anterior 

 coccygeal bones. 



Depressor coccygis is attached to the under surfaces of 

 the anterior coccygeal bones, its fibres pass downwards 

 towards the anus and become confounded with those of 

 levator ani. 



The tail is supplied with blood by the lateral and middle 

 coccygeal arteries, with nerve force by coccygeal branches 

 from the posterior part of the spinal cord. 



