950 



THE URINARY BLADDER. 



The third stratum of fibres, still more deeply situated, and which might be 

 termed internal longitudinal, was first described by Ellis, who distinguished 

 it as "submucous." It is very delicate, and its fibres, directed longitu- 

 dinally, are scattered in a regular manner round the cavity of the bladder. 



The researches of Pettigrew (including an elaborate series of dissections 

 preserved in the Museum of the Royal College of Surgeons of England) 

 have led him to the conclusion that, with few exceptions, the muscular 

 fibres of all the strata are arranged in figure-8 loops. These loops are 

 directed towards the apex and base, and he regards them as disposed in 

 four sets ; an anterior and a posterior set largely developed, and a right and 

 a left lateral set accessory and less fully developed ; and they are so arranged 

 that at any one spot on the bladder there are to be found decussating 

 groups of fibres, which may be distinguished as longitudinal, horizontal or 

 transverse, and oblique. The extremities of each figure-8 are placed on one 

 aspect of the bladder, and the point of decussation on the opposite aspect ; 

 the arrangement being thus similar to that of a string wound in figure-3 

 loops round a cylinder. In each set the most superficial loops are com- 

 pressed laterally and elongated from above downwards, but the succeeding 

 loops as they become more deeply placed are more and more drawn out trans- 

 versely until those which are nearly circular are reached ; and on passing more 

 deeply than these, the loops become again gradually more and more elongated 

 until those which have been alluded to as internal longitudinal are arrived at. 

 The figure-8 arrangement, stated by Pettigrew to exist in all the groups, is 

 moat distinctly seen in the anterior set, which may here be more particularly 

 alluded to. The most superficial fibres of. this set form a narrow band some 

 of which are prolonged on the urachus, while others pass round close behind 

 its insertion ; their decussation takes place about midway between the 

 summit of the bladder and the urethra ; and inferiorly they pass forwards 

 to be inserted into the capsule of the prostate, the posterior surface of the 

 pubes, the inner border of the levator ani, and the fascia covering the 

 constrictor urethras muscle. The points of decussation of the deeper fibres 



Fig. 667. 



Fig. 667. VIEW OP THE MUSCULAR 

 FIBRES OP THE BLADDER FROM THE 

 LEFT SIDE (after Pettigrew and 

 from Nature). 



The anterior and posterior super- 

 ficial fibres are seen in profile running 

 from below upwards, crossing each 

 other by their divergence on the sides 

 of the bladder, and are indicated by 

 the same letters as in the previous 

 figures ; at c, a portion of the anterior 

 longitudinal fibres has been removed so 

 as to expose the deeper circular fibres. 



as they become more horizontal, 

 are placed lower and lower down. 

 The fibres which cross obliquely 

 are most expanded, and embrace 

 the larger parts of the bladder, 

 taking part, on the posterior 

 wall, in the formation of the so- 

 called circular layer, while the fibres which at their decussation are more 

 nearly horizontal are confined to the regions of the base and neck. The 



