290 THE ANATOMY OF THE HORSE. 



to that in structure and appearance, save that it is smoother. The 

 inner layer is thinner, quite hairless, and devoid of glands, and pos- 

 teriorly it is reflected on to the penis, to become continuous with the 

 cutaneous investment of that organ. 



Directions. — Assuming that the penis is fully retracted, the student 

 will be able to bring the prepuce proper into view by dilating as widely 

 as possible the orifice of the sheath. Lying within it will be seen the 

 extremity of the penis, and by seizing the latter and dragging it for- 

 wards the student may give the parts the relationships which they 

 assume during erection. It will be observed that during this act the 

 prepuce proper becomes entirely obliterated, passing on to the body of 

 the penis, and that the tube of the sheath is also partially obliterated 

 in the same way. 



Suspensory Ligaments of the prepuce. When the outer cutaneous 

 layer of the prepuce is removed, there is exposed an elastic fibrous layer 

 which descends into it on each side from the abdominal tunic. These 

 are the suspensory ligaments of the prepuce. 



Vessels and Nerves. The cutaneous nerves of the prepuce and scro- 

 tum are branches of the inguinal nerve or nerves. One or more of 

 these, derived from the 2nd and 3rd lumbar nerves, descend through 

 the inguinal canal. The arteries are branches of the subcutaneous 

 abdominal artery. This vessel, which is a branch of the external pudic 

 artery, passes forwards a few inches from the middle line. The trunk 

 of the artery is to be left undisturbed at present. 



A rich plexus of veins exists in and around the scrotum. This 

 plexus is drained by a comparatively small vein that accompanies the 

 external pudic artery, and by a larger vessel which penetrates the 

 gracilis to empty itself into the femoral vein. 



THE PENIS. 



Directions. — While the penis is pulled forwards, reflect the integu- 

 mental covering from the upper face of its free portion, and follow back- 

 wards its dorsal vessels and nerves. 



Dorsal Arteries of the penis (Plates 39 and 46). On each side there 

 are two of these, distinguished as anterior and posterior. 1. The anterior 

 dorsal artery of the penis is one of the terminal branches of the external 

 pudic artery. It results from the bifurcation of that vessel imme- 

 diately after its emergence from the inguinal canal, and after a course 

 of a few inches it divides into an anterior branch which passes forwards 

 on the free portion of the penis, and a posterior which passes backwards 

 on the fixed portion, meeting and anastomosing with the posterior 

 dorsal artery. When the penis is non-erect the anterior of these 

 branches has a flexuous disposition, which permits it to be elongated 



