386 HUMAN ANATOMY. 



Superficial perineal fascia consists of superficial fat layer 

 and deep membranous layer. The former is continuous with 

 subcutaneous layer of buttocks, thigh, and labia, and posterior 

 to anus become continuous with tissue of ischio-rectal fossa. 

 The superior layer passes from rami of pubis and ischium to the 

 tuberosity of ischia, covering ischio-cavernous and bulbo-urethral 

 muscles, and becomes continuous with the deep perineal fascia. 



The deep perineal fascia (triangular ligament) is a strong 

 triangular membrane extending between the rami ischii et pubis, 

 its apex attached to the under surface of the symphysis. It is 

 often described as consisting of two layers, the anterior and poste- 

 rior (superior and inferior). It is pierced by the membranous 

 urethra, and sends a fascia surrounding the urethral glands to 

 the spongy body. In the female it is weaker, the urethra also 

 pierces it, and it is continuous with the fascia of the vagina. 



Muscles of the Perineum. 

 & 



ISCHIO-CAVERNOUS (erector penis) arises in the inner sur- 

 face of the tuberosity of the ischium, and is inserted into the 

 side and under surface of the crus penis. In the female there is a 

 similar insertion into the clitoris. It serves to maintain the 

 organ erect. Nerve, perineal. 



BULBO-CAVERNOUS (accelerator urinaa, ejaculator seminis) 

 arises from central tendon of perineum and from median raphe 

 in front. It spreads out and is inserted from behind forward to 

 anterior surface of triangular ligament, bulb and adjacent part 

 of corpus spongiosum, to join fibres of opposite side, and to sides 

 of corpora cavernosa; anterior to erector penis and in fibrous 

 expansion over dorsal blood-vessels of penis. 



It accelerates the flow of urine and semen and contributes 

 to erection of the penis. Nerve, perineal. 



VAGINAL CONSTRICTOR (sphincter vaginae), analogous to 

 foregoing muscle, surrounds the orifice of vagina. It arises 

 from the central tendon and passes forward on either side of 

 vagina to be inserted into the corpora cavernosa and body of 

 clitoris. It compresses the dorsal vein of the clitoris. 



ERECTOR CLITORIDIS corresponds to erector penis muscle in 

 the male, but smaller. 



TRANSVERSE PERINEAL arises from inner part of ramus of 

 ischium, and is inserted into perineal centre in male, into the 

 side of sphincter vaginae in the female. It steadies the perineal 

 centre. Nerve, perineal. 



DEPRESSOR URETHRA, or Jarjavay's muscle, arises from the 

 rami ischii, and joins the constrictor and its fellow of the oppo- 

 site side over the urethra. Nerve, perineal. 



