622 A MANUAL OF ANATOMY 



line. Each gland is a firm, round, and lobulated mass about the 

 size of a small pea. Both glands are ensheathed by the lower layer 

 of the compressor urethrae muscle, and within this there is the 

 special fibrous capsule which has an admixture of plain muscular 

 tissue. The glands belong to the class of racemose or acino-tubular 

 glands, and each is composed of several lobules. The alveoli or 

 acini are lined with columnar cells. The ducts are two in number, 

 right and left. They are lined with cubical epithelium, and their 

 walls contain plain muscular tissue. Each duct pierces the antero- 

 inferior layer of the triangular ligament on either side of the urethral 

 opening, a little behind and below the artery of the bulb. The duct 

 then pierces the side of the bulb, and opens, with its fellow, upon 

 the floor of the bulbous part of the urethra, fully i inch in front 

 of the antero-inferior layer of the triangular ligament. Each gland 

 receives a branch from the artery of the bulb. 



Cowper's glands are developed from the epithelial lining of the uro-genital 

 sinus or canal. 



Internal Pudic Artery. — ^This vessel is one of the terminal branches 

 of the anterior division of the internal iliac, the other and larger 

 terminal branch being the sciatic. Lying at first within the pelvis, 

 the artery passes downwards over the pyriformis muscle and sacral 

 nerves, having the sciatic artery usually behind it, and it emerges 

 from the cavity through the lower compartment of the great sacro- 

 sciatic foramen. It then crosses the back of the spine of the 

 ischium, after which it passes through the small sacro-sciatic 

 foramen, and so enters the ischio-rectal division of the perineum. 

 The vessel now courses along the outer wall of the ischio-rectal 

 fossa, where, contained in Alcock's canal, it lies about li inches 

 above the lower part of the tuber ischii. On approaching the 

 anterior part of the fossa the artery gradually becomes more 

 superficial, and, after leaving the fossa, it enters the interspace 

 between the two layers of the triangular ligament of the urethra by 

 piercing the postero-superior layer close to its base and near the 

 ischial ramus. It now passes forwards and upwards, embedded in 

 the compressor urethrae muscle, and lying close to the ischio-pubic 

 ramus, where it is comparatively superficial. Having given off 

 the artery of the bulb about ^ inch above the base of the triangular 

 ligament, the vessel finally divides, about i inch below the subpubic 

 angle, into its two terminal branches, the artery of the corpus 

 cavernosum and the dorsal artery of the penis. 



In considering the relations and branches of the internal pudic 

 artery it is convenient to divide the vessel into four parts — first, 

 second, third, and fourth. 



The first part represents the intrapelvic portion of the vessel, and 

 will be found described on p. 843 . 



The second part is the portion of the vessel which lies upon the 1 

 back of the spine of the ischium. For a description of it see 

 p. 433. I 



