THE PENIS 



1261 



composed of fibrous connective tissue, which has resting upon it the m. ischio- 

 cavernosus (see Section IV). The two crura are situated in the lateral portions 

 of the superficial perineal interspace and pass forward parallel with the rami of 

 the ischia and pubis, gradually becoming transformed into cavernous erectile 

 tissue. Shortly before they reach the level of the symphysis pubis the two 

 corpora come into contact in the median line, their medial walls fusing to form a 

 septum, and thus united they extend throughout the entire length of the body of 

 the penis, occupying the dorsal portion of the space enclosed by the fascia penis 

 (fig. 1022) . They terminate at the posterior surface of the glans, where they taper 



Fig. 1023. 



-Dissection of the Perineum Showing the Structure and Relations of the 



Penis. 



Corona glandis — 



Corpus cavernosum penis- 



Glans perns 



Corpus cavernosum urethraE 



Pubis ■ 



■ M. ischio-cavernosus 



_Bulb 



Ischium 



. Urogenital trigone 

 (diaphragm) 



Prostate gland 



somewhat to be received into its basal concavity (fig. 1024). The septum in its 

 proximal part forms a complete partition between the two bodies, but distally it 

 is broken through by numerous clefts by which the blood lacunae of the two bodies 

 are placed in communication. 



Each corpus cavernosum penis cons'sts of a strong elastic fibrous sheath, the tunica albu- 

 ginea, from which trabeculse extend into the substance of the organ, dividing it into a network 

 of communicating cavities, into which open terminal branches of the a. profunda penis, which 

 traverses the axis of the corpus. These cavities consequently are to be regarded as vascular 

 laciinse, which, becoming engorged with blood, produce the enlargement and erection of the 

 organ. 



The third erectile organ is the corpus cavernosum urethras (formerly "corpus 

 spongiosum") (fig. 1023), so called because it is traversed throughout its entire 

 length by the urethra (fig. 1024). It is an unpaired, median structure, having no 



