160 ERECTILE TISSUE. 



find it assisting in forming the organ of the nose, ear, and 

 trachea, and consequently taking part in the functions of 

 respiration, hearing and smelling. By being placed be- 

 tween articular surfaces, it prevents concussion, and in the 

 trochleas, it facilitates the movement of tendons. 



CHAPTEK XL 



ERECTILE TISSUE. 



THE corpora cavernosa, in the penis of the male, the 

 clitoris of the female, the nymphas, the tissues around the 

 vaginae, and the nipple in both sexes, are all regarded as 

 specimens of the erectile tissue. 



This tissue, it is believed, consists essentially of a plexus 

 of varicose veins, surrounded by a fibrous envelope. The 

 cause of erection, or turgescence, in the penis and clitoris, 

 called turgor-vitaliSj has been ascribed to compression of 

 the vena dorsalis against the symphysis pubis, and to the 

 action of the ischio-cavernosi muscles. That such cannot 

 be the cause in all cases, may be safely inferred from the 

 fact that there is no such compression nor any such muscles 

 acting upon the nipple where this erection equally occurs. 



According to Gerber the venous plexus is traversed by 

 numerous contractile fibres, whose contraction causes ob- 

 struction in the venous circulation, producing thereby the 

 turgescence and erection. Valentin describes a tendinous 

 tissue between the anastomosing veins, having muscles at- 

 tached to it, which he supposes the active cause of the erec- 

 tion ; but his reasons for regarding such structure as mus- 

 cular, are not considered conclusive. Muller says the ex- 

 citing cause is nervous irritation, proceeding from the brain 

 and spinal marrow, or arising in the part itself, and that 

 the pudic nerves are the means of transmitting the nervous 

 influence ; as from the experiments of Guenther, it seems 

 the penis was incapable of erection when these nerves were 

 divided. Muller has discovered a set of arteries which he 



