244 



DISSECTION OF THE PERINEUM. 



Define parti- 

 tion be- 

 tween thigh 

 and perineal 

 space. 



On right 

 side seek 

 inferior 

 pudendal 

 nerve. 



Superficial 

 fascia : 



subcuta- 

 neous part ; 



and mem- 

 branous 

 layer. 



The latter 

 forms a 

 pouch, open 

 in front ; 

 and divided 

 by a septum 



Course of 

 air and 

 effused 

 urine. 



Dissection 

 of nerves 

 and vessels 

 on right 



side. 



Superficial 

 vessels of 

 pudic. 



To show more completely the attachment of this layer to the hip. 

 bone between the perineal space and the thigh, it will be necessary to 

 take away from the left limb the fat on the fascia lata, external to the 

 margin of the bone. 



In the fat of the thigh on the right side the student should seek 

 the inferior or long pudendal nerve (fig. 92), which pierces the fascia 

 lata one inch in front of the ischial tuberosity, and about the same 

 distance from the margin of the bone ; and he should trace its junc- 

 tion in the fat with the inferior haemorrhoidal nerve. Afterwards the 

 nerve is to be followed forwards to where it passes beneath the 

 superficial fascia nearer the middle line. 



The superficial fascia of the anterior half of the perineum is com- 

 posed of two layers, which differ in their characters and relations. 



One is the subcutaneous fatty part, continuous with that of the 

 adjoining regions : its thickness, and the quantity of fat in it vary 

 with the condition of the body. Passing in front into the scrotum, 

 it there loses its fat, and contains involuntary muscular fibres, forming 

 the layer known as the tunica dartos. 



The other layer (fascia of Colles, and beneath which the air was 

 injected) is a more membranous stratum of limited extent, and is con- 

 nected with the firm subjacent structures. Externally it is fixed to the 

 conjoined rami of the ischium and pubis, outside the line of the cms 

 penis and its muscle, extending as far back as the ischial tuberosity. 

 Posteriorly this layer bends upwards to join the triangular ligament 

 of the urethra ; but in front it is unattached, and is continued to the 

 scrotum and penis. By means of the connections of the mem- 

 brane on both sides, a space is enclosed over the anterior half of the 

 perineum. From its deep surface a septum extends upwards in the 

 . middle line, and divides posteriorly the subjacent space into two: 

 but anteriorly this partition is less perfect, or may disappear. 



Air blown beneath the fascia passes forwards to the scrotum; 

 which is the only possible direction owing to the deep connections 

 of the membrane with parts around. Should urine be effused 

 beneath the superficial fascia, the fluid will be directed forwards, 

 like the air, through the scrotum to the penis and the front of the 

 abdomen. 



Dissection, The superficial vessels and nerves are to be dissected 

 on the right side .of the perineum, by cutting through the super- 

 ficial fascia in the same manner as on the left side. The long 

 slender artery then visible is the superficial perineal, which gives 

 a transverse branch near its commencement. Two superficial peri- 

 neal nerves accompany the artery ; and the inferior pudendal nerve 

 is to be traced forward to the scrotum. Communications are to be 

 sought between these nerves anteriorly, and between one of the 

 perineal and the inferior haemorrhoidal posteriorly ; and all the 

 nerves are to be followed backwards (figs. 92 and 93). 



ARTEBIES (figs. 92 and 93). The superficial and transverse perineal 

 arteries beneath the fascia are branches of the pudic, and are two or 

 three in number. 



