626 



A MANUAL OF ANATOMY 



crosses the back of the spine of the ischium, where it lies under 

 cover of the gluteus maximus and on the inner side of the internal 

 pudic vessels. It then passes through the small sacro-sciatic 

 foramen, and so enters Alcock's canal in the outer wall of the ischio- 

 rectal fossa. Immediately after doing so, it divides into three 

 branches, namely, inferior hemorrhoidal, perineal, and dorsal nerve 

 of the penis. 



The inferior hemorrhoidal nerve passes inwards across the ischio- 

 rectal fossa to the region of the anus, and is distributed to the 

 external sphincter muscle and the integument which covers the 

 ischio-rectal fossa. 



Scrotum 



Fascia of Colles 

 (right halO *"'~->^_ 



Superficial Perineal/ '~~----___ ff ^ 

 Nerves \ ~77 '^ 



■ M 



Long Pudendal Nerve of- — ^-^ 



Soemmering 



Superficial Transverse-- ». 



Perineal Muscle /// 



Inferior Hemorrhoidal 



Nerve 



Gluteal Cutaneous •-«-■ 

 Branches of Small 

 Sciatic Nerve 



Perforating Cutaneous Nerve 



— Central Tendinous Point 



. Superficial Perineal Artery 



— Transverse Perineal Artery 



-- Internal Pudic Artery in 

 Alcock's Canal 

 -Inferior Hemorrhoidal 

 Artery 



- Gluteal Cutaneous Branches 

 of Sciatic Artery 



Hemorrhoidal or Perineal Branch 

 of 4th Sacral Nerve 



Fig. 277. — Dissection of the Male Perineum 



(On the left side the bulbo-cavernosus has been removed, and the crus 



penis cut). 



The perineal nerve is a large branch which passes forwards in 

 Alcock's canal, being the lowest of its contents. It ultimately 

 divides into superficial and deep branches. 



The superficial branches are two in number, and are called the 

 external or posterior, and internal or anterior, superficial perineal 

 nerves. Both nerves, having emerged from Alcock's canal, pass 

 forwards and pierce the base of the antero-inferior layer of the 

 triangular ligament. They then run forwards with the superficial 

 perineal artery under cover of the fascia of Colles, and on approach- 



