COATS OF THE BLADDER. MUCOUS MEMBRANE. 951 



whole of the muscular fibres around the prostate and prostatic portion of the 

 urethra are supposed by Pettigrew to be formed by the lower extremities of 

 the various figures-8. The general idea of this figure-8 arrangement was 

 first suggested by Sabatier, by whom the more marked examples of it are 

 described ; but it has been fully elaborated by the researches of Pettigrew. 



A strong muscular bundle already alluded to passes, as shown by Ellis, 

 with its convexity forwards between the terminations of the ureters, con- 

 tinuous with the longitudinal fibres of these tubes. Other fibres mentioned 

 by Morgagni, and more fully described under the name of the " muscles of 

 the ureters " by Sir C. Bell, pass forwards from the ureters towards the 

 urethra : they are considered by Pettigrew not as special structures, but 

 as a part of the general arrangement of fibres in that part of the bladder. 



On the muscular arrangements of the bladder, see Pettigrew, in Phil. 

 Trans, for 1866 ; Sabatier, Kech. Anat. et Phys. sur les Appareils 

 musculaires correspondents k la vessie et k la prostate dans les deux *<exes, 

 1864 ; and in Henle's Jahresbericht ; Ellis, in Trans. Med. Chir. Society, 

 1856, and Demonstrations, 1861. 



The muscular coat of the bladder forms so irregular a covering, that, when the organ 

 is much distended, intervals arise in which the walls are very thin; and, should the 

 internal or mucous lining protrude in any spot through the muscular bundles, a sort 

 of hernia is produced, which may go on increasing, so as to form what is called a 

 vesieal sacculus, or appendix vesicce, the bladder thus affected being termed sacculated. 

 Hypertrophy of the muscular fasciculi, which is liable to occur in stricture of the 

 urethra or other affections impeding the issue of the urine, gives rise to that condition 

 named the fasciculated bladder, in which the interior of the organ is marked by strong 

 reticulated ridges or columns, with intervening depressions. 



Next to the muscular coat, between it and the mucous membrane, but 

 much more intimately connected with the latter, is a well-marked layer of 

 areolar tissue,, frequently named the cellular or vascular coat. This sub- 

 mucous areular layer contains a large quantity of very fine coiled fibres of 

 elastic tissue. 



The mucous membrane of the bladder is soft, smooth, and of a pale rose 

 colour. It is continuous above with the lining membrane of the ureters 

 and kidneys, and below with that of the urethra. It adheres loosely to 

 the muscular tissue, and is thus liable to be thrown into "wrinkles, except at 

 the trigoue, where it is consequently always more even. It is covered 

 with a stratified epithelium, the particles of which are intermediate in form 

 between those of the columnar and squamous varieties. There are no villi 

 upon the vesical mucous membrane, but it is provided with minute follicles, 

 and small racemose glands lined with columnar epithelium, which are most 

 abundant in the vicinity of the neck of the bladder. The vesical mucus 

 (according to Mandl) is alkaline, and appears to contain alkaline and earthy 

 phosphates. 



Vessels. The superior vesical arteries proceed from the remaining pervious 

 portions of the hypogastric arteries; in the adult they appear as direct branches 

 of the internal iliac. The inferior vesical arteries are usually derived from the anterior 

 division of the internal iliac. In the female the uterine arteries also send branches to 

 the bladder. The neck and base of the organ appear to be the most vascular portions. 

 The veins form large plexuses around the neck, sides and base of the bladder; they 

 eventually pass into the internal iliac veins. The lymphatics follow a similar course. 



The nerves are derived partly from the hypogastric plexus of the sympathetic, and 

 partly from the sacral plexus of the cerebro-spinal system. The former are said to he 

 chiefly distributed to the upper part of the bladder, whilst the spinal nerves may be. 

 traced more directly to its neck and base. 



