THE INTERNAL FEMORAL REGION. 513 



This muscle is pierced, near its insertion, by the middle perforating branch of 

 the profunda femoris artery. 



The Adductor brevis should now be cut away sear its origin, and turned outward, when 

 the entire extent of the Adductor -inagnus will be exposed. 



The Adductor magnus is a large triangular muscle forming a septum between 

 the muscles on the inner and those on the back of the thigh. It arises from a 

 small part of the descending ramus of the os pubis, from the ascending ramus 

 of the ischium, and from the outer margin and under surface of the tuberosity 

 of the ischium. Those fibres which arise from the ramus of the os pubis 

 are very short, horizontal in direction, and are inserted into the rough line 

 leading from the great trochanter to the linea aspera, internal to the Gluteus 

 maximus; those from the ramus of the ischium are directed downward and 

 outward with different degrees of obliquity, to be inserted, by means of a broad 

 aponeurosis. into the linea aspera and the upper part of its internal prolonga- 

 tion below. The internal portion of the muscle, consisting principally of those 

 fibres which arise from the tuberositv of the ischium, forms a thick fleshy mass 

 consisting of coarse bundles which descend almost vertically, and terminate about 

 the lower third of the thigh in a rounded tendon, which is inserted into the 

 Adductor tubercle on the inner condyle of the femur, being connected by a fibrous 

 expansion to the line leading upward from the tubercle to the linea aspera. 

 Between the two portions of the muscle an interval is left, tendinous in front, 

 fleshy behind, for the passage of the femoral vessels into the popliteal space. The 

 external portion of the muscle at its attachment to the femur presents three or four 

 osseo-aponeurotic openings, formed by tendinous arches attached to the bone, from 

 which muscular fibres arise. The three superior of these apertures are for the 

 three perforating arteries, and the fourth, when it exists, for the terminal branch 

 of the profunda. 



Relations. By its anterior surface, with the Pectineus. Adductor brevis. 

 Adductor longus, and the femoral and profunda vessels and obturator nerve ; by 

 its posterior surface, with the great sciatic nerve, the Gluteus maximus. Biceps, 

 Semitendinosus, and Semimembranosus. By its superior or shortest border it lies 

 parallel with the Quadratus femoris, the internal circumflex artery passing between 

 them : by its internal or longest border, with the Gracilis, Sartorius, and fascia 

 lata : by its external or attache-: 1 border it is inserted into the femur behind the 

 Adductor brevis and Adductor longus, which separate it from the Vastus internus, 

 and in front of the Gluteus maximus and short head of the Biceps, which separate 

 it from the A astus externus. 



Nerves. All the muscles of this group are supplied by the obturator nerve. 

 The Pectineus receives additional branches from the accessory obturator and ante- 

 rior crural, and the Adductor magnus an additional branch from the great sciatic. 



Actions. The Pectineus and three Adductors adduct the thigh powerfully : 

 they are especially used in horse exercise, the flanks of the horse being grasped 

 between the knees by the actions of these muscles. In consequence of the obliquity 

 of their insertion into the linea aspera they rotate the thigh outward, assisting 

 the external Rotators, and when the limb has been abducted they draw it inward, 

 carrying the thigh across that of the opposite side. The Pectineus and Adductor 

 brevis and longus assist the Psoas and Iliacus in flexing the thigh upon the pelvis. 

 In progression, also, all these muscles assist in drawing forward the hinder limb. 

 The Gracilis assists the Sartorius in flexing the leg and rotating it inward ; it is 

 also an adductor of the thigh. If the lower extremities are fixed, these muscles 

 may take their fixed point from below and act upon the pelvis, serving to maintain 

 the body in an erect posture, or, if their action is continued, to flex the pelvis 

 forward upon the femur. 



Surgical Anatomy. The Adductor longus is liable to be severely strained in those 

 who ride much on horseback, or its tendon to be ruptured by suddenly gripping the saddle. 

 And. occasionally, especially in cavalry soldiers, the tendon may become ossified, constituting the 

 "rider's bone/' 



33 



