256 ELEMENTS OF HISTOLOGY. [Ch ; , P . xxxi. 



met with around it. The matrix of the corpus 

 cavernosum consists of trabeculse of fibrous tissue, 

 between which pass bundles of non-striped muscular 

 tissue all in different directions. Innumerable 

 cavernse or sinuses, intercommunicating with one 

 another, are present in this matrix, capable of such 

 considerable repletion, that in the maximum degree 

 of this state the sinuses are almost in contact, 

 and the trabeculse compressed into very delicate 

 septa. The sinuses are lined with a single layer of 

 flattened endothelial plates, and their wall in many 

 places is strengthened by the bundles of non-striped 

 muscular tissue. The sinuses during erection become 

 filled with blood, being directly continuous with capil- 

 lary blood-vessels. These are derived from the arte- 

 rial branches which take their course in the above 

 trabeculse of the matrix. The blood passes from the 

 sinuses into small efferent veins. But the blood 

 passes also directly from the capillaries into the 

 efferent veins, and this is the course the blood takes 

 under passive conditions, while during erection it 

 passes chiefly into the above sinuses. 



342. In the peripheral part of the corpus caver- 

 nosum there exists a direct communication between the 

 sinuses and minute arteries (Langer), but in the rest 

 the arteries do not directly communicate with the 

 sinuses except through the capillary blood-vessels. 

 In the passive state of the corpus cavernosum, the 

 muscular trabeculse forming part of the matrix are 

 contracted, and the minute arterial branches embedded 

 in them are therefore much coiled up ; these are the 

 arterise helicinae. 



