SACRAL AND COCCYGEAL 655 



rior branch of the internal cutaneous; below the knee, with other branches of the 

 long saphenous; and, on the outer side of the joint, with branches of the middle 

 and external cutaneous nerves, forming a plexiform network, the plexus patellae. 

 The cutaneous nerve of the patella is occasionally small, and terminates by 

 joining the internal cutaneous, which supplies its place in front of the knee. 



Below the knee, the branches of the long saphenous nerve are distributed to 

 the integument of the front and inner side of the leg, communicating with the 

 cutaneous branches from the internal cutaneous, or obturator nerve. 



The Deep Group of branches of the anterior crural nerve are muscular and 

 articular. 



The muscular branches supply the Pectineus, and all the muscles on the front 

 of the thigh, except the Tensor Vaginas Femoris, which is supplied from the 

 superior gluteal nerve, and the Sartorius, which is supplied by filaments from 

 the middle or internal cutaneous nerves. 



The branches to the Pectineus, usually two in number, pass inwards behind 

 the femoral vessels, and enter the muscle on its anterior surface. 



The branch to the Rectus muscle enters its under surface high up. 



The branch to the Vastus Externus, of large size, follows the course of the 

 descending branch of the external circumflex artery, to the lower part of the 

 muscle. It gives off an articular filament. 



The branches to the Vastus Internus and Crureus enter the middle of those 

 muscles. 



The articular branches, two in number, supply the knee-joint. One, a long 

 slender filament, is derived from the nerve to the Vastus Externus. It pene- 

 trates the capsular ligament of the joint on its anterior aspect. The other is 

 derived from the nerve to the Vastus Internus. It descends along the internal 

 intermuscular septum, accompanying the deep branch of the anastomotica 

 magna artery, pierces the capsular ligament of the joint on its inner side, and 

 supplies the synovial membrane. 



THE SACRAL AND COCCYGEAL NERVES. 



The sacral nerves are five in number on each side. The four upper ones pass 

 from the sacral canal, through the sacral foramina; the fifth through the fora- 

 men between the sacrum and coccyx. 



The roots of origin of the upper sacral (and lumbar) nerves are the largest of 

 all the spinal nerves; whilst those of the lowest sacral and coccygeal nerve are 

 the smallest. 



The roots of these nerves are of very considerable length, being longer than 

 those of any of the other spinal nerves, on account of the spinal cord not 

 extending beyond the first lumbar vertebra. From their great length, and the 

 appearance they present in connection with the spinal cord, the roots of origin 

 of these nerves are called collectively the cauda equina. Each sacral and 

 coccygeal nerve divides into two branches, anterior and posterior. 



The posterior sacral nerves are small, diminish in size from above down- 

 wards, and emerge, except the last, from the sacral canal by the posterior sacral 

 formina. 



The three upper ones are covered, at their exit from the sacral canal, by the 

 Multifidus spinse, and divide into external and internal branches. 



The internal branches are small, and supply the Multifidus Spinae. 



The external branches communicate with one another, and with the last 

 lumbar and fourth sacral nerves, by means of anastomosing loops. These 

 branches pass outwards, to the outer surface of the great sacro-sciatic ligament, 

 where they form a second series of loops beneath the Gluteus Maximus. Cuta- 

 neous branches from this second series of loops, usually three in number, pierce 

 the Gluteus Maximus, one near the posterior inferior spine of the ilium; another 

 opposite the end of the sacrum; and the third, midway between the other twoi 

 They supply the integument over the posterior part of the gluteal region. 



