OBTURATOR NERVE AND BRANCHES. 577 



The accessory obturator nerve 1 (Schmidt) is derived from the trunk of 

 the obturator, near the lumbar plexus (p. 497), and passes from the abdo- 

 men over the brim of the pelvis. In the thigh it turns beneath the pecli- 

 neus, and joins the superficial part of the obturator nerve ; it supplies an 

 offset to the hip-joint with the articular artery, and occasionally one to 

 the under surface of the pectineus. 



The ADDUCTOR BKEVIS (fig. 198, D ) has a thin fleshy and aponeurotic 

 attachment, about two inches in depth, to the front of the hip-bone with 

 the gracilis. The muscle arises from the pubic border of the bone close 

 to and outside the gracilis, reaching upwards as high as the adductor lon- 

 gus, and not quite so low as the gracilis. It is inserted, behind the pecti- 

 neus, into all the line leading from the lineaaspera to the small trochanter. 



In front of the muscle are the pectineus and the adductor longus, with 

 the superficial piece of the obturator nerve, and the profunda artery ; but 

 it is gradually uncovered by the adductor longus below, and the contiguous 

 borders of the two are side by side at their insertion into the femur. Be- 

 hind the muscle is the adductor magnus, with the deep piece of the obtu- 

 rator nerve and a branch of the inner circumflex artery. In contact with 

 the upper border is the obturator externus, F, and the internal circumflex 

 artery passes between the two. 



Action. This muscle adducts the limb with slight flexion of the hip- 

 joint, like the pectineus. And if it acts from the femur it .will balance 

 and move forwards the pelvis. 



The OBTURATOR NERVE (fig. 198, ') is a branch of the lumbar plexus 

 (p. 497), and supplies the adductor muscles of the thigh, as well as the 

 hip and knee joints. The nerve issues from the pelvis through the aper- 

 ture in the upper part of the thyroid foramen ; and it divides in that open- 

 ing into two pieces, which are named superficial and deep from their posi- 

 tion with respect to the adductor brevis muscle. 



A. The superficial part ( : ) of the nerve is directed over the adductor 

 brevis, but beneath the pectineus and the adductor longus, to the femoral 

 artery, on which it is distributed ; at the lower border of the last muscle it 

 furnishes an offset or two to join in a plexus with the internal cutaneous 

 and saphenous nerves (p. 573), and supply the teguments. 2 



Near the pelvis or in the aperture of exit, this piece of the nerve sends 

 outwards an articular twig to the hip joint with the joint-artery. 



Muscular branches are furnished to the adductor longus, the adductor 

 brevis, and the gracilis. 



B. The deep part (*) of the obturator nerve pierces the fibres of the ex- 

 ternal obturator muscle, and continuing beneath the adductor brevis is con- 

 sumed chiefly in the adductor magnus. The following offsets are supplied 

 by it : 



Muscular branches enter the obturator externus as the nerve pierces it ; 

 others are furnished to the large, and sometimes to the short adductor. 



A slender articular branch (fig. 198, 5 ) enters the fibres of the adductor 

 magnus, and passes through it near the linea aspera to reach the popliteal 



1 This small nerve is often absent ; it was found only four or five times in nine 

 or ten bodies which were examined by its discoverer. The name given to it by 

 Schmidt refers to this irregularity, viz., nerv. ad obturatorem accessorius incon- 

 stans. Comuientarius de Nervis Lumbalibus. 



2 In some bodies the superficial part of the nerve is of large size, and has a dis- 

 tribution similar to that of the inner branch of the internal cutaneous nerve, whose 

 place it takes : in such instances it joins freely in the plexus. 



37 



