igS OPERATIVE TECHNIQUE. 



Professor McFadyean remarks of layers 3, 4 and 5 that the dis- 

 sector will probabl}' be unable to discriminate between them. These 

 three layers, being adherent, are often referred to by Continental 

 surgeons as the processus vaginalis communis or common vaginal 

 sheath. Though anatomically incorrect, this method of regarding 

 the three coverings is sometimes convenient to the surgeon as 

 obviating a lengthy description. The tunica vaginalis reflexa is 

 sack-like in form ; above, where it lies in the inguinal canal, it 

 is much narrower than below, where it surrounds the testicles. 

 Its narrowest point is rather more than an inch below the inner 

 inguinal ring, thence it gradual)}' dilates as it descends ; as a 

 whole its outline resembles that of an hour glass. In the space 

 enclosed by this prolongation of the vaginal tunic are found the 

 testicle and spermatic cord ; in the horse the testicle lies horizon- 

 tall}*, in ruminants vertically, with the epidid}'mis pointing downwards. 



7. The testicular cord is a flattened, longish, fan-shaped structure, 

 connected at its lower, broader end to the testicle, whilst its upper 

 portion extends into the abdominal cavity. It is invested by the 

 visceral layer of the tunica vaginalis, a prolongation of the visceral 

 peritoneum, and consists of the following parts : 



(a) The vas deferens, which is placed at the posterior part of the 

 spermatic cord, is a thick-walled tube, representing the excretory 

 duct of the testicle, in large animals of the size of a goose-quill, 

 surrounded by a fold of peritoneum and situated on the inner side of 

 the spermatic cord; by its convolutions it forms the epidid}mis, ihe 

 anterior enlargement of which is termed the globus major on account 

 of its greater size, the posterior the globus minor; the intermediate 

 part is called the body. The vas deferens enters the peritoneal 

 cavity through the inguinal canal, passes backwards, surrounded by a 

 special fold of peritoneum, towards the upper surface of the urinary 

 bladder and empties b}' the ejaculatory duct into the urethra. 



{b) The spermatic vessels and nerves. The spermatic artery lies in 

 the front part of the spermatic cord and is accompanied by the large 

 and tortuous spermatic veins, the convolutions of which form the plexus 

 pampiniformis. The upper portions of the vessels pass, enveloped in 

 a fold of peritoneum, from the inner inguinal ring to the posterior 

 aorta and the posterior vena cava respectively. 



The anterior portion of the cord (the vascular portion) therefore 

 contains the important blood-vessels, whilst the posterior is com- 

 parativel}' poor in vessels, a point of great importance in connection 

 with castration. The parietal layer of the tunica vaginalis, which 

 surrounds the spermatic cord just as the parietal layer of peritoneum 

 surrounds the abdominal viscera, extends from the posterior wall of 

 the vaginal space to the posterior septum of the spermatic cord, and 

 thus binds the cord to the scrotum. 



The inguinal canal consists of a. flattened, funnel-shaped space 

 between the abdominal coats, communicating above through the 

 medium of the inner abdominal ring with the peritoneal cavity, and 

 below by the outer abdominal ring with the interior of the scrotum. 

 The outer abdominal ring, an cval opening between the inner and outer 



