THE PENIS. 1965 



side on account of the greater length of the left spermatic cord) and lax. Advantage 

 of these facts is taken in certain operative procedures, as in making the flaps in Roux's 

 operation for vesical exstrophy, or excising a portion of the scrotum (to secure firmer 

 support for the vascular structures of the cord) in varicocele. 



The redundancy, thinness, and elasticity of the skin and the laxity of the fatless 

 areolar tissue connecting the internal and external layers combine to favor : (a) marked 

 discoloration and great extravasation of blood in cases of hemorrhage from the vessels 

 between the two layers ; hence in orchitis leeches are applied, not over the scrotum, 

 but in the line of the cord in the groin ; (<5) extreme distention, as in large scrotal 

 herniae, in hydrocele, in bulky testicular tumors ; (c) extensive oedema in general 

 anasarca, as a result of pelvic venous thrombosis, or accompanying an infectious cellu- 

 litis or an extravasation of urine, which, when it proceeds from a solution of contin- 

 uity anterior to the triangular ligament, is directed by Colles's fascia into this cellular 

 space between the two layers. The thinness of the scrotal skin, increased when it 

 is distended, makes it, in spite of its vascularity, very susceptible to gangrene from 

 pressure, as in " strapping' ' an inflamed testicle, or from underlying celluUtis. 



The longitudinal contractile fibres of the dartos draw the redundant skin into 

 transverse rugae which, by retaining extraneous dirt and the secretions of the sweat- 

 glands and sebaceous follicles, become often the starting-point of eczema, of mucous 

 patches, or even (as in " chimney-sweep's cancer" ) of epithelioma. The contractil- 

 ity of the dartos is marked in young and robust persons, and is increased by cold, by 

 sexual excitement, and by light friction. It is lessened in old age, by debility, or by 

 continued warmth and moisture, the scrotum, in the presence of those conditions, 

 becoming smooth, elongated, and pendulous. It is useful in aiding the scrotum to 

 regain its normal size after distention, as following the tapping of a hydrocele or the 

 removal of a tumor. On the other hand, the dartos tends to inxert the edges of a 

 scrotal wound (as the platysma does those of a wound of the neck), and warm appli- 

 cations may therefore be useful before a scrotal incision is sutured. 



The muscular (cremasteric ) element of the inner layer gives it contractility, and 

 the intimate connection between it, the deeper (infundibuliform) plane of fascia, and 

 the parietal layer of the tunica vaginalis enables it to elevate the testicle with its 

 coverings when it is excited to contraction. This may be done {cremasteric rejlex) 

 by drawing the finger-nail over the skin of the thigh a little below Poupart's liga- 

 ment, the sensory impression being conveyed from the skin through the crural branch, 

 and to the cremaster through the genital branch, of the genito-crural nerve. 



The infundibuliform (internal spermatic) fascia, by its close relation to the pos- 

 tero-inferior portion of the testicle, on the one hand, and to the external scrotal layer, 

 on the other, assists the scrotal ligament (page 2042) in preventing the testicle from 

 being floated up when the space between the two layers of the tunica vaginalis is 

 filled with fluid (hydrocele, haematocele), and holds it in the lower back part of the 

 scrotum. 



In exploratory puncture, or in the tapping of hydrocele, the spot selected is 

 therefore on the anterior surface of the upper two-thirds of the scrotum, care being 

 taken to avoid the large superficial veins. 



THE PENIS. 



The penis, the organ of copulation of the male, consists of three cylinders of 

 erectile tissue — the paired corpora cavernosa and the single corpus spongiosum — 

 united with one another and invested by coverings of fascia and skin. Since the 

 upper or proximal portion of the penis fpars perinealis) is buried beneath the integu- 

 ment and fascia of the perineum and the scrotum, only the free pendulous distal 

 portion of the organ is visible in the undissected subject. 



When exposed throughout its entire extent, the penis presents a cylindrical shaft 

 or body (corpus penis), which begins above in a three-pronged root (radix penis) 

 attached to the pubic arch and the triangular ligament and terminates below in a 

 blunted conical end, the glayis penis. The anterior or upper surface (dorsum penis) 

 is somewhat flattened and formed by the corpora cavernosa. The posterior, under, 

 or urethral surface (facies urethralis) corresponds to the corpus spongiosum, traversed 



