THE ABDOMEN 671 



the spermatic plexus have valves, but they are not competent. 

 There is, however, a competent valve as a rule at the termination 

 of each spermatic vein. 



The lymphatics of the testis and spermatic cord, the spermatic 

 plexus of sympathetic nerves, and the genital branch of the genito- 

 crural nerve will be afterwards described. 



Coverings of the Spermatic Cord. — ^The coverings, enumerated from 

 within outwards, are as follows : 



1. The subperitoneal areolar tissue, which is continuous with 

 that of the abdominal wall through the internal abdominal ring. 

 It contains a certain amoimt of muscular tissue, which is known as 

 the middle cremaster. 



2. The fascia transversalis, prolonged from the margins of the 

 internal abdominal ring, and known as the uUernal spermatic 

 fascia. This covering near the ring is funnel-shaped, and is thence 

 called the infundibuliform fascia, but lower down it becomes 

 incorporated with the subperitoneal areolar tissue, and forms the 

 fascia propria of Cooper. 



3. The cremasteric fascia, or middle spermatic fascia. 



4. The intercolumnar fascia, or external spermatic fascia. 



5. The tunica dartos. 



6. The skin. 



Within the innermost of these coverings there are a few scattered 

 muscular fibres, which constitute the internal cremaster of Henle, 

 and which are regarded as representing the inverted lateral bands of 

 the gubernaculum testis. 



It is to be noted that the middle cremaster is the muscular tissue 

 contained in the subperitoneal areolar tissue on the surface of the 

 cord, whilst the external cremaster is the more distinct muscular 

 structure which is derived from the lower border of the internal 

 oblique. The fibres of the external cremaster are of the striated 

 variety, but those of the middle and internal are of the plain variety. 



Descent of Testis and Formation ol Inguinal Canal. — The testis originally 

 lies in the lumbar region of the abdomen upon the psoas magnus muscle, on 

 a level with the last thoracic and first lumbar vertebrae. It is situated on the 

 mesial side of the Wolffian body or mesonephros and behind the peritoneum, 

 the epitheUal cells of the peritoneum being the superficial cells of the germinal 

 epithelium. 



In order to understand the descent of the sexual organ (testis or ovary) it 

 is necessary to refer to certain embryological structures. 



As stated, the testis (as well as the ovary) is situated on the mesial side of 

 the Wolffian body. The sexual organ is attached to the mesial part of the 

 Wolffian body by a short peritoneal fold, called the meso-testis or mesorchium 

 in the male, and the mesovarium in the female. The Wolffian body is 

 attached to the posterior abdominal wall by a peritoneal fold, the so-called 

 Wolffian mesentery (more strictly Wolffian ligament). External to the 

 Wolffian body there are (i) the Wolffian duct, which gives origin to the epi- 

 didymis, vas deferens, and common ejaculatorj' duct, and (2) the Miillerian 

 duct, from which the uterus and vagina are developed. These two ducts — 

 Wolffian and Miillerian — he within a fold of peritoneum, called the urogenital 

 lold, by which they are attached to the outer part of the Wolffian bod}', the 

 Miillerian duct, at this level lying upon the outer side of the Wolffian duct. 



k 



