360 ABDOMEN 



from the margin of the pubic arch at the junction of the 

 pubic and ischial rami. Expanding as it passes medially, 

 it unites with its fellows of the opposite side in a medial 

 raphe below and behind the membranous part of the urethra. 

 Its posterior border lies in the angle between the superficial 

 and deep fascial layers of the urogenital diaphragm, and its 

 anterior border is blended with the external layer of the 

 sphincter muscle of the membranous urethra. The sphincter 

 of the membranous iirethra consists of internal and external 

 groups of fibres. The internal group is formed of circular 

 fibres which embrace the urethra ; they are continuous above 

 with the muscular fibres of the prostate and below with the 

 circular muscular fibres around the posterior part of the 

 cavernous portion of the urethra. The external layer consists 

 of transverse fibres which rise, together with the deep trans- 

 verse muscle of the perineum, from the margin of the pubic 

 arch and from the superficial layer of the urogenital diaphragm. 

 As they approach the median plane some of the fibres pass 

 anterior and some posterior to the membranous part of the 

 urethra, where they blend with the corresponding fibres of the 

 opposite side. These muscles are supplied by one or two 

 delicate twigs from the perineal division of the pudendal nerve. 



Glandulse Bulbo-urethrales (O.T. Cowper's Glands). As a 

 general rule, these glands can readily be detected by raising 

 the posterior fibres of the deep transverse perineal muscles. 

 They are small lobulated bodies of a deep yellow colour, and 

 resemble peas both in size and shape. They are placed one 

 on each side of the middle line, immediately below the 

 membranous part of the urethra, and are overlapped by the 

 posterior part of the bulb separated from it, however, by 

 the superficial fascia of the urogenital diaphragm. From 

 each a minute duct proceeds, but this duct does not open 

 into the membranous portion of the urethra. It passes 

 forwards between the wall of the urethra and the substance 

 of the bulb for the distance of one inch, and opens on the 

 floor of the cavernous part of the urethra. 



Art. Pudenda Interna (O.T. Internal Pudic). The in- 

 ternal pudendal artery is a branch of the hypogastric. It 

 is met with in three different regions of the body viz. 

 (i) within the cavity of the pelvis; (2) in the glutaeal region, 

 where it lies upon the spine of the ischium ; and (3) in 

 the perineal space. It is consequently described as con- 



