208 INFERIOR EXTREMITY 



pectineus. It proceeds posteriorly through the adductor 

 brevis and adductor magnus. The arteria perforans secunda 

 takes origin a short distance lower down, or perhaps by a 

 common trunk with the first perforating. It pierces the 

 same muscles, viz. the adductor brevis and adductor magnus. 

 The arteria perforans tertia springs from the profunda distal 

 to the adductor brevis, and passes posteriorly through the 

 adductor magnus. The arteria perforans quarta, as before 

 noted, is the terminal branch of the profunda femoris ; it 

 pierces the adductor magnus alone. 



The arteria nutricia femoris superior may spring from 

 either the second or the third perforating branch. An inferior 

 nutrient artery is frequently present ; it is often derived from 

 the fourth perforating artery. 



When the adductor magnus is more fully exposed it will 

 be seen that the perforating arteries, as they pierce its tendon, 

 have a series of fibrous arches thrown over them. 



M. Pectineus. This muscle is placed between the 

 adductor longus and the ilio-psoas. It is flat and somewhat 

 broader at its origin from the brim of the pelvis than at its 

 insertion into the femur. It has a fleshy origin, from the 

 pecten pubis, and from the surface of the innominate 

 bone anterior to it (Fig. 74, p. 200). Some fibres are 

 likewise derived from the lacunar ligament. It descends 

 obliquely laterally and posteriorly, and gains insertion into 

 the femur, posterior to the lesser trochanter, and to a certain 

 extent also into the line which leads from that prominence 

 down to the linea aspera. It is supplied by the femoral nerve. 



Dissection. The pectineus may be detached from its origin, and thrown 

 distal ly and laterally. In separating the muscle from the pubis the dis- 

 sector must bear in mind that in some cases an accessory obturator nerve 

 descends into the thigh, under cover of its lateral margin, and over the brim 

 of the pelvis. Care must also be taken not to injure the anterior division 

 of the obturator nerve which lies posterior to the muscle, or the medial 

 circumflex artery which passes posteriorly in contact with its lateral border. 



The Nervus Obturatorius Accessorius when present arises within the 

 abdomen from the lumbar plexus or from (Fig. 208) the obturator trunk near 

 its origin. In the thigh it gives a branch to the hip-joint and joins the 

 anterior division of the obturator nerve. It is very rare to find a twig 

 given to the pectineus either by it or by the trunk of the obturator nerve 

 itself. 



Art. Circumflexa Femoris Medialis (O.T. Internal Circum- 

 flex) This vessel springs from the medial and posterior aspect 

 of the profunda femoris artery at the same level as the lateral 



