338 MUSCLES OF THE ANUS. 



Inserted into the accelerator urinae, and into that part of the 

 sphincter ani which covers the bulb. The place of junction of 

 these muscles is called the perineal point or centre. 



Use. To dilate the bulb, and draw the perineum and verge of 

 the anus a little outwards and backwards. 



There is often a fourth muscle, named 







Transversus Perinei Alter, 



Arises behind the former, runs more obliquely forwards, and is 

 Inserted into that part of the accelerator urinae which covers 

 the anterior part of the bulb of the urethra. 

 Use. To assist the former. 



In the Medico-Chirurgical Transactions, James Wilson, Esq. F. R. S. gives 

 the following account of two small muscles of the membranous part of the 

 urethra, viz: Each muscle has a tendon which, at first, is round, but soon be- 

 comes flattened as it descends. It is affixed to the back part of the symphysis 

 pubis, about one-eighth of an inch above the lower edge of the cartilaginous 

 arch of the pubes, and nearly at the same distance, below the attachment of the 

 tendon of the bladder : to which, and to the tendon of the corresponding muscle, 

 it is connected by very loose cellular membrane. The tendon descends at first 

 in contact with, and parallel to, its fellow : it soon becomes broader, and sends 

 off fleshy fibres, which also increase in breadth, and, when near the upper sur- 

 face of the membranous part of the urethra, separate from those of the opposite 

 side, spread themselves on the side of the membranous part of the urethra 

 through its whole extent ; then fold themselves under it, and meet in a middle 

 tendinous line with similar fibres of the opposite side. 



Its action seems to be to draw up the membranous part of the urethra, and 

 compress it against the inside of the cartilaginous arch of the pubes ; and also 

 to contract the circle round the membranous portion, so as to diminish and even 

 close up the passage of the urine.* It is known under the name of the muscle 

 of Wilson .f 



* I have frequently dissected for this muscle, and in only two or three cases have been 

 able to satisfy myself of its having an existence distinct from that of the Levator Ani. My 

 friend, Mr. Shaw, who occupies a distinguished rank among the cultivators of anatomy in 

 London, admits of this muscle, but says there is much difficulty in distinguishing it from the 

 ligament of the urethra, meaning, I presume, its triangular ligament. H. 



f The vertical muscular fibres discovered by Mr. Wilson and a transverse band connected 

 with it, described by Mr. Guthrie, and both together commonly considered now as forming 

 the proper compressor urethra muscle. From repeated examination, I have no doubt of 

 their being properly entitled to this name. The muscle of Guthrie arises by a tendinous 

 point from the ranus of the Ischium and passing transversely inwards, splits into two layers 

 which by junction with its fellow of the opposite side, embrace the upper and lower surface 

 of the membranous portion of the urethrae from the bulb to which it is connected as front 

 to the point of the mastale to which it is attached behind. p. 



