ADDENDUM TO THE ARTICLE URETHRA. 



In justice to a distinguished anatomist and surgeon, Mr. Henry Hancock, whose claims 

 to priority of the discovery of unstriped muscular fibres in the urethra were over- 

 looked by the author of the article URETHRA, the Editor thinks it right, with the as- 

 sent of the author of that article, to insert the following paragraph, drawn up by 

 Mr. Hancock, as an addendum to it : 



THE urethra itself is a membranous tube, 

 consisting of mucous membrane, presenting 

 villi on its free surface for the most part 

 arranged in rows, some being conical, others 

 tuberculated, covered by epithelial scales. 

 The outer surface of the urethra is closely 

 invested by cellular tissue, external to which 

 is found a layer of organic muscular fibres, 

 similar to, and in fact continuous with, the 

 muscular coat of the bladder. This last- 

 named structure consists of two layers, an 

 internal and an external ; the external passes 

 forwards on the outside of the prostate 

 gland ; the internal, on the contrary, accom- 

 panies the mucous lining of the bladder, when 

 it becomes urethral through the prostate 

 gland, forming a covering of involuntary 

 muscular fibre to the canal in its passage 

 through the gland. In front of the prostate, 

 the two layers of muscular fibre unite and 

 invest the membranous portion of the urethra, 

 where they may easily be distinguished from 

 the voluntary muscles of the part. Reaching 

 the bulb they again separate into an internal 

 and an external layer ; the internal continues 

 forwards to the orifice of the urethra, lying 

 between that canal and the corpus spongio- 

 sum ; the external passes on the outer sur- 

 face of the corpus spongiosum, separating 



it from its fibrous investment, to which the 

 fibres adhere pretty closely. These latter, 

 like the internal, are continued forward to 

 the orifice of the urethra, and in their course 

 they invest the spongy portion of the bulb, 

 the urethra, and the glans penis, entering 

 very largely into the formation of the peculiar 

 structure found at the orifice of the urethra, 

 and which appears to consist almost entirely 

 of involuntary muscle and cellular tissue. 

 Hence, the corpus spongiosum urethrae lies 

 between two layers of involuntary muscle, 

 the one separating it from the urethra, the 

 other from its fibrous investment ; and this 

 arrangement obtains wherever the corpus 

 spongiosum exists, whether the quantity 

 thereof be small or great. On the under and 

 lateral portion of the urethra, where the quan- 

 tity is abundant, the corpus spongiosum lies 

 between two layers of involuntary muscular 

 fibre. On the upper surface of the urethra, 

 where the quantity is comparatively small, 

 the same arrangement may be observed, whilst 

 at the glans, which is not formed merely by 

 increased development of the spongy tissue, 

 but also by a folding back, as it were, of the 

 spongy tissue over the corpora cavernosa, we 

 find these muscular layers multiplied. 



