THE SCROTUM. 1963 



and the tunica dartos, a layer of modified subcutaneous tissue — the superficial fascia — 

 distinguished by the presence of numerous longitudinally disposed bundles of invol- 

 untary muscle-fibres and much elastic tissue and by the entire absence of fat. 



The muscular tissue {dartos muscle), where best developed, as in the anterior 

 and lateral walls of the scrotum, is sufificient in quantity to be recognized as a dis- 

 tinct layer, but so closely attached to the integument as to form practically a part of 

 it. At the raphe, while some fibres follow the skin and remain superficial, the majority 

 enter the septum, being especially well developed in the lower part, and at the attached 

 upper border pass over into the dartos of the penis and the perineum.. The numerous 

 bundles of elastic tissue within the tunica dartos in the upper and anterior part of the 

 scrotum become condensed into robust bands which efftciently aid in supporting the 

 scrotal sac, since they are continued laterally at the sides of the penis and over the 

 spermatic cords into the superficial fascia of the abdomen, and in the mid-line blend 

 with the suspensory ligament of the penis. Those on the posterior surface are 

 attached over the pubic and ischial rami. 



Enumerated from without inward, the layers interposed between the surface of 

 the scrotum and the serous cavity surrounding the testis are : '( i) the skin, (2) the 

 modified superficial fascia or tunica dartos, (3) the inter columnar fascia, (4) the cre- 

 ■masteric fascia, (5) the infundibuliform fascia, and (6) the t^inica vaginalis. Of 

 these the first two alone, strictly considered, are contributed by the scrotum, the 

 remaining layers being derived from the deeper structures of the abdominal wall and 

 associated with the descent of the testicle. The connection between the tunica dartos 

 and the underlying intercolumnar fascia is by no means firm, being effected by a loose 

 layer of areolar tissue, devoid of fat, that permits a ready separation, particularly in 

 front, between the external scrotal envelope and the coverings proper of the testis. 

 Beneath the posterior surface of the scrotum the connection is firmer (Disse). This 

 separation, however, is arrested at the lower part of the scrotum, owing to the presence 

 of the scrotal ligament (Fig. 1723), a mass of fibrous tissue that anchors the lower 

 end of the tunica vaginalis and the testicle to the external envelopes. 



With the exception of the serous coat, the tunica vaginalis, these coverings have 

 been considered in connection with the spermatic cord (page i960) ; it remains, there- 

 fore, to describe more fully the serous coat to which incidental reference has been made 

 (page 1 941) in its relations to the testis and the epididymis. 



The production of an isolated, closed serous sac within each half of the scrotum 

 results from partial obliteration of the serous pouch, the processus vaginalis, that 

 during foetal life extends from the general peritoneal cavity into the scrotum in an- 

 ticipation of the descent of the sexual gland. 



The tunica vaginalis (tunica vaginalis propria testis), in correspondence with 

 other serous membranes, consists of a parietal and a visceral portion, the latter pro- 

 viding an extensive but incomplete investment for the testis and the epididymis and 

 the former lining the serous cavity into which these organs, thus covered, project. 

 With the exception of small spaces caused by the elevation of the epididymis, espe- 

 cially of the globus major, these two layers are practically in contact and separated 

 by only a capillary cleft. Whatever space exists is filled by a clear straw-colored 

 serous fluid. 



In addition to walling the cavity, xhe parietal layer invests the spermatic cord for 

 about 12 mm. above the testicle and the blood-vessels behind, and then is continued 

 into the visceral layer along the line of reflection that passes over the back of the 

 testis to its lower pole on the one side and along the posterior surface of the epi- 

 didymis on the other, thus leaving an intervening uncovered strip as a passage-way 

 for the duct, vessels, and nerves. 



From the line of reflection the thin visceral layer completely invests the testis 

 and the epididymis, adhering intimately with the tunica albuginea, and dipping 

 deeply between these organs to form the digital fossa (sinus epididymidis). This 

 pocket (Fig. 1650), the entrance to which is narrowed by two transverse folds (liga- 

 menta epididymidis superior et inferior), may be so deep that the serous membrane at 

 its bottom is in contact with that reflected from the median side of the testicle. Nu- 

 merous bundles of involuntary muscle — the m. cremaster interniis of Henle — radiate 

 from the scrotal ligament at the lower part of the scrotum to spread out between the 



