492 ANATOMY IN A NUTSHELL. 



Accelerator urinae. — ( Bulbo-cavernosus-Ejaculator seminis.) — Descrip- 

 tion. -This muscle is situated in the middle line of the perineum just in front 

 of the anus. It consists of two similar parts united in the middle line by a 

 tendinous raphe. 



Origin. From the central tendon of the perineum, and from the median 

 raphe in trout. 



Insertion.— Into the anterior surface of the triangular ligament into the 

 hull) and adjacent parts of the corpus spongiosum, and into the tunica albu- 

 genia of corpora cavernosa. 



Action.— To empty the urethra and assist the erector penis. 



Nerve Supply. —Perineal branch of the internal pudic. 



Blood Supply. — Superficial perineal from internal pudic. 



Erector penis. — ( [schio-cavernosus.) — Description. — This muscle covers 

 part of the cms penis and is situated on either side of the lateral boundary of 

 the perineum. This muscle is broad in the middle and narrow at the extrem- 

 ities. 



Origin. — From the inner surface of the tuberosity of the ischium, from 

 the surface of the cms, and from the adjacent portion of the ramus of the ischium. 



[nsertion. — Into the sides and into the under surface of the crus penis 

 by an aponeurosis. 



Action". — By compressing the crus penis, it retards the blood through the 

 veins and in this manner keeps the organ erect. 



Nerve Supply. — Perineal branch of internal pudic. 



Blood Supply.— Superficial perineal from internal pudic. 



Compressor urethra'. — (Constrictor urethra'. ) — DESCRIPTION. — This muscle 

 is situated between the two layers of the triangular ligament and surrounds the 

 membranous portion of the urethra. 



Origin.— From the junction of the rami of the os pubis and ischium, ex- 

 tending to half an inch or more. 



[nsertion. Each portion of this muscle divides into two fasciculi which 

 surround the urethra from the prostate gland behind to the bulbous portion of 

 the urethra in front. They mute at the upper and lower surfaces of this tube 

 with the muscle of the opposite side. 



Action. These muscles acting together assist expelling the fluids and 

 compressing the membranous portion of the urethra. 



Nerve Supply.— Perineal branch of the internal pudic. 



Blood Supply. — Superficial perineal from internal pudic. 



LESSON CLXI. 

 Mcs< lesofthe Perineum ixthk Female. ( Plate CCLXXI.) 



Transversus periiuei. DESCRIPTION. — This is a small muscular slip in the 

 female which passes across the back part of the perineal space. 



Okioiw From the inner and forepart of the tuberosity of the ischium by 

 a small tendon. 



