Anatomy of Skeleton 



The inner edge of Psoas, lying on the area of bone C, just overlaps the outer edge 

 of Pectineus, and the pubic portion of fascia lata that covers Pectineus sends a deep 

 sheet under Psoas to the pubo- femoral band and to the bone above this along the line a. 



Notice that when the bone is in its proper position the plane of the ischio-pubic 

 adductor surface looks downwards as well as outwards and forwards, so that the group 

 pf Adductor muscles is below the Obturator externus as well as in front of it. 



Arterial branches of the obturator (0.) and internal circumflex (I.C.) run on the 

 hone among the muscle origins as shown in the plate. 



Looked at from above, the bone exhibits the iliac fossa most clearly, with certain 

 other parts. Fig. 109 is a sketch of the bone seen in this way : the origin of Iliacus 

 is indicated in outline in the fossa. Examine the back and inner part (x) of its area, 

 above and external to the auricular surface, and the surface of the bone will be found 

 somewhat lined; the markings are not in the direction of the muscular fibres, and 

 are not made by them, but by a thick ligamentous layer that covers the bone as a 

 prolongation of the sacro-iliac ligamentous system. Iliacus arises from these, and from 

 the rest of its area on the bone, by muscle fibre. 



The muscle covers the bone between its origin and the mesial aspect of the anterior 

 inferior spine ; internal to it the Psoas lies on the bone. The brim of the pelvis in 

 front turns inwards away from the line of Psoas, and the triangular area thus made is 

 covered by Pectineus : observe that this has a linear origin except where it arises by 

 muscle fibre outside and behind the pubic spine. 



The line a marks the attachment of a fascial layer from the pubic part of fascia 

 lata, deep to edge of Psoas, so can be taken as showing the division between the sur- 

 faces covered by Psoas and Pectineus respectively. Notice that the pectineal area 

 can be looked on as a prolongation of the iliac fossa, and the Pectineus is considered 

 to be a portion of Iliacus, which, from the situation of its origin, has a different func- 

 tional value and therefore has separated from the main sheet : this would account 

 for its nerve supply differing from that of the adductors with which it is descriptively 

 grouped. 



Gimbernat's ligament is attached to the front end of the ilio-pectineal line behind 

 Pectineus, and conjoint tendon again immediately behind this : these two structures 

 are necessarily directly continuous with the front wall of the sheath of the Rectus, the 

 former through its connection with Poupart's ligament attached to the spine, the latter 

 along an attachment in a groove (g) just internal to the spine and immediately external 

 to the origin of Rectus from the crest. 



(These arrangements of the structures can perhaps be understood better by 

 reference to the plan in Fig. no.) 



Iliacus and Psoas are covered by the Iliac fascia, which is attached to the margins of the fossa 

 In Fig. 109 the dotted line i.f. on the inner margin of the crest marks its attachment here : in front 

 it passes on to the posterior aspect of Poupart's ligament, behind it reaches the ilio-lumbar ligament 

 below the Quadratus lumborum, and from this passes over the Psoas. 



Its inner attachment can be picked up on the ilio-pectineal line internal to the Psoas : it is 

 attached along this line; reinforced along the Pectineus by the pubic part of fascia lata, and reaches 

 Gimbernat's ligament. Its attachment is from this along the free edge of Gimbernat's to the back 

 of Poupart's ligament, and thus to the crest of the Ilium. 



The sheet of fascia can thus be regarded as a simple layer attached round the 

 margins of the fossa, and continuous at the outer and front margins with the plane of 

 transversalis fascia. 



When the main vessels, lying on it, proceed under Poupart's ligament, they must 

 carry with them a process of the fascia, attached in front or above to the back of 



