THE PUDIC NERVE. 617 
plexus, merely accompanying the pudic nerve in the first part of its course; in 
exceptional cases the perforating cutaneous nerve of the buttock is a branch of the 
pudic nerve. 
The inferior hemorrhoidal nerve (n. hemorrhoidalis inferior) arises from the 
pudic nerve under cover of the gluteus maximus, at the posterior part of the ischio- 
rectal fossa. In cases in which it has an independent origin from the plexus, it 
arises from the third and fourth sacral nerves. It crosses the ischio-rectal fossa in 
company with the inferior hemorrhoidal vessels and separates into numerous 
branches—muscular, cutaneous, and communicating. 
The muscular branches end in the external sphincter muscle. ‘The cutaneous 
branches supply the skin around the anus. The communicating branches connect 
the inferior hemorrhoidal with three other nerves—the perineal branches of the 
small sciatic, pudic, and fourth sacral nerves. 
The perineal nerve (n. perineus), one of the two terminal branches of the 
pudic nerve, arises near the base of the triangular ligament. It almost immediately 
divides into two parts, superficial and deep. 
The superficial part is purely cutaneous and consists of two nerves, the posterior 
or external and the anterior or internal superficial perineal nerves, which pass, 
along with the superficial perineal vessels, to the anterior part of the perineum. 
Corpus cavernosum 
(cut) 
NERVE TO CORPUS_ 
CAVERNOSUM 
NERVE TO DORSUM 
OF PENIS 
Compressor urethra 
_—— Bulb of penis 
Triangular hgament 
(anterior layer) 
NERVE TO BULB 
Triangular ligament 
(posterior layer) 
INTERNAL PUDIC NERVE 
—Crus penis 
\ . 
Tga\9 Levator ani 
Fic. 448.—THE TRIANGULAR LIGAMENT OF THE PERINEUM. 
The posterior or external superficial perineal nerve, at the anterior limit of the ischio- 
rectal fossa, usually passes over the base of the triangular ligament and the trans- 
versus perinei muscle. The anterior or internal superficial perineal nerve, lying more 
deeply, pierces the base of the triangular ligament and goes underneath or through 
the transversus perinei muscle. Becoming superficial in the anterior (urethral) 
triangle of the perineum, they are distributed to the skin of the scrotum (or labium 
majus), and communicate with the perineal branch of the small sciatic nerve and 
with the inferior heemorrhoidal nerve. 
The deep part of the perineal nerve is mainly but not entirely muscular. 
Coursing forwards through the anterior part of the ischio-rectal fossa, it passes 
between the two layers of the triangular ligament towards the urethra. It supplies 
muscular branches to the anterior parts of the levator ani and external sphincter, 
to the transversus perinei, erector penis (or clitoridis), bulbo-cavernosus (ejaculator 
urine or sphincter vagine), and compressor urethre. It terminates as the nerve 
to the bulb, which, piercing the triangular ligament, enters the bulb of the urethra 
and supplies the erectile tissue of the bulb and corpus spongiosum, as well as the 
mucous membrane of the urethra as far as the glans penis (or clitoridis). 
