DISSECTING MANUAL. 



at the lower border of the Popliteus it becomes the posterior 

 tibial when the upper part is called the internal popliteal. Its 

 branches to the hip- joint and muscles of the thigh arise appar- 

 ently from the great sciatic and have just been described. Its 

 branches below the knee-joint will be described with the leg. 

 Branches arising in popliteal space. Articular; an azygos 

 branch pierces the posterior ligament of the knee-joint; an in- 

 ternal branch (inconstant) crosses the popliteal vessels and de- 

 scends with the lower internal articular artery to the inner side 

 of the knee-joint. Muscular; one each to the Plantaris and 

 both heads of the Gastrocnemius, entering them at the borders 

 of the popliteal space; one to the Sole us, entering it superfi- 

 cially; one to the Popliteus, descending over it and around its 

 lower border to its anterior surface. The latter branch also 

 supplies the Tibialis posticus, interosseous membrane, tibia, 

 and upper tibio-fibular joint. Cutaneous (tibial communicat- 

 ing) ; descending between the heads of the Gastrocnemii to the 

 back of the leg. [652] 



PUDENDAL PLEXUS. 



This lies on the back wall of the pelvis and is formed by 

 fibres from the first three sacral nerves and all the fourth and 

 fifth sacral and the coccygeal. A visceral branch (white ramus 

 communicans) runs from the third (and second or fourth) sa- 

 cral to the pelvic plexus and viscera. The other branches are 

 the small sciatic, perforating cutaneous, pudic, muscular, and 

 sacro-coccygeal. The perforating cutaneous arises from the 

 back of the second and third sacral nerves and runs through 

 the great sacro-sciatic ligament to the buttock. The muscular 

 branches arise from a loop between the third and fourth sacral 

 and supply the Levator ani, Coccygeus, and External sphincter; 

 offsets from the latter branch supply the skin on the ischio- 

 rectal fossa and fold of the nates behind the anus. The ante- 

 rior sacro-coccygeal consist of descending branches from the 

 fourth and fifth sacral and the coccygeal which form a 

 plexus (coccygeal) besides the coccyx; twigs from this run 



[286] 



