S 



ANATOMY OF THE PERINEUM. 203 



superficial perineal artery ; this passes forward to the 

 scrotum, giving off in its course a branch called the trans- 

 versalis perinei, which crosses the perineum upon the 

 trans versus perinei muscle. 



These arteries are accompanied by small branches from 

 the internal pudic and perineal cutaneous nerves. 



The internal pudic nerve is an offset from the sacral 

 lexus, which takes the course of the internal pudic artery, 

 nd divides into a superior and inferior branch, the former 

 oing to the penis, the latter to the scrotum and perineum. 



The perineal cutaneous nerve comes from the lesser 



iatic, and ascends along the ramus of the ischium to 

 apply the scrotum and the integument below the penis. 



The preceding dissection will have exposed several mus- 

 cles, small in size, but, with a single exception, sufficiently 

 well marked to be readily recognized. 



The SPHINCTER ANI is an elliptical-shaped muscle, sur- 

 ounding the anus. It arises from the tip of the coccyx, 



d is inserted an inch or more in front of the anus in 

 common with two other muscles, hereafter to be described, 

 into a fibrous spot called the perineal centre. Deeper in 

 the pelvis, but continuous with this muscle, will be seen 

 the circular fibres proper to the rectum itself; these con- 

 stitute the sphincter ani internus ; by removing all the fat 

 and cellular tissue from the ischio-rectal fossa, it will be 

 seen that these muscles blend with, and become lost in the 

 lower part of the levator ani muscle, which comes down 

 from each side of the pelvis, and surrounds the gut, as 

 will hereafter be observed on making a section of the pelvic 

 cavity. 



The TRANSVERSUS PERINEI MUSCLE is a small bundle of 

 fibres, occasionally wanting on one or both sides, which 

 arises from the tuberosity of the ischium, and is inserted 

 into the perineal centre. A slip, arising in common with 

 this, sometimes passes forward, and becomes blended with 

 the accelerator urinae ; this is called the transversus perinei 

 alter. 



The ERECTOR PENIS arises from the tuberosity and ramus 

 of the ischium by a strong tendon, and forming a round, 

 fleshy belly, is inserted on the side of the penis into the 

 strong fascia investing the corpus cavernosum. 



The ACCELERATORES TIRING lie upon the corpus spon- 

 giosum of the penis; arising from the perineal centre and 

 the raphe that separates them, their fibres diverge to 



