MUSCLES OF THE PERINEUM AND ANUS. 123 



of the scrotum ; behind it is continuous with the base of the 

 triangular ligament by its anterior lamina,^'^ and also with the anal 

 fascia,'^^ a portion of the pelvic fascia. It is this connexion which 

 prevents the urine infiltrating the fascia lining the cavity of the 

 pelvis, which would be most disastrous, and which also renders 

 fluctuation indistinct in abscess of the perineum. If this be turned 

 up, the muscles of the perineum will be exposed. 



The triangular ligament^ fills up the arch of the pubis, and is 

 shaped as its name implies. It is a fibrous membrane, separating 

 the pelvis from the perineum ; the base is not so dense and fibrous 

 as its apex, and joins the perineal and anal fascia.^^ It is perforated 

 by the membranous portion of the urethra, about one inch below the 

 symphysis. 



It consists of two laminse,^^ ^ between which are situated Cowper's 

 and the prostate gland 'i' thus the fascia of the prostate, as it is 

 usually called, is merely the posterior lamina of the triangular 

 ligament. 



PELVIC FASCIA. 



This fascia is continuous with the transversalis and iliac fascia, 

 surrounding that portion of the peritoneum which lines the pelvis. 

 Like all fascise it is easily divided into laminee ; different portions 

 receiving different names. 



It may be said to commence at the brim of the pelvis, and by its 

 intervention the different viscera are united with each, and held in 

 their proper positions. Thus, two processes of it on the sides of 

 the bladder form the anterior ligaments of the bladder. A layer 

 covering the obturator muscle is called the obturator fascia. The 

 levator ani is included between two layers of this fascia ; that por- 

 tion between the rectum and bladder is called the recto-vesical fascia ; 

 and that which covers the lower part of the rectum is the anal 

 fascia. 



MUSCLES OF THE PERINEUM AND ANUS. 



Erector penis.^ — Origi?t, from the tuberosity of the ischium. 

 Insertion^ by a broad flat tendon into corpus cavernosum. 



Accelerator urincE,^ or ejaciilator seminis. — It lies on the bulb of 

 the corpus spongiosum. Ongi?t, from the crus of the penis, and 

 the ramus of the pubes ; and also by a tendinous membrane which 

 is between the corpus spongiosum and corpus cavernosum, and 

 continuous with the fascia of the penis. The fibres are semi-pennate, 

 and with those of its fellow surround the bulb. Insertion, by a 

 white tendinous line into its fellow, and into the perineal centre, 

 which is formed by the junction of several muscles. 



Tra?isversus perinei.* — Arises from the tuberosity of the ischium, 



