ANATOMY OF THE FEMALE ORGANS OF GENEKATION 73 



Wilson's Muscle. — This muscle is composed of two portions, oue 

 spread over the upper, and the other over the lower surface of the mem- 

 branous portion of the urethra. At either side the two layers unite 

 together, and are attached right and left to the inner lateral wall of the 

 pelvis. 



When the two layers of this muscle contract, the walls of the urethra 

 are brought together, and the escape of urine from the bladder is pre- 

 vented. By the same means it prevents the semen from entering the 

 bladder when it emerges from the vesiculee seminales in the act of copu- 

 lation. 



Two other muscles, the " ischio-urethral " and the "transverse perinei ", 

 are also concerned in acting upon the urethra. 



MUSCLES OF THE PENIS 



Erector Penis (a, fig. 227). — These are two short, thick fleshy muscles 

 which arise from the crest of the ischium, and are inserted into the cruras 

 of the penis. 



They assist in bringing about erection, by preventing the free outflow 

 of blood from the corpora cavernosa and causing an engorgement of its 

 cells and vessels. 



Retractor Penis (c, fig. 227). — This consists of two bands of pale 

 unstriped muscle, which arise from the under surface of the coccygeal or 

 tail bones, and after winding round the rectum converge together below 

 the anal opening, and are continued forward beneath the corpus spon- 

 giosum to the extremity of the penis. 



Contracting, they draw the penis back into the sheath after erection. 



ANATOMY OF THE FEMALE ORGANS OF GENERATION 



The entrance to the uro-genital passage in the female is a vertical 

 fissure some 4 or 5 inches in length, bounded on each side by a skin 

 fold (the labium magnus). The folds meet above at an acute angle, 

 separated from the anus by a bare, usually dark-coloured patch of skin, 

 about 2 inches in extent, known as the " perineum ". Below, the meeting 

 of the lips is more obtuse. Supporting the folds, and passing round the 

 opening, is a voluntary muscle {jwst sphincte?-), which is separated from 

 the skin by a considerable quantity of loose areolar tissue. 



If the labia are separated it will be seen that they are covered inter- 

 nally by a smooth, moist, pale-coloured mucous membrane. Just within 

 the lips, in the lower angle of the fissure, will be noticed a small prominence 



