The Lower Extremity and Pelvis 133 



the falciform ridge to the lower border of the everted surface : this shows the attach- 

 ment of Colics' fascia to the bone. 



The deep layer of the triangular ligament is attached to the bone in the line of the 

 lower and front attachment of the parietal fascia, and this can as a rule be found on 

 the bone without difficulty : the Compressor urethrae can now be placed on the bone, 

 and behind this the two layers of the triangular ligament are seen to fuse, so that they 

 form a single layer at their bony attachment, when they are joined by Colics' fascia. 



The various lines of fasciae are shown in No. 2 in Fig. in, where the superficial 

 layer and deep are placed as blue lines and Colics' fascia green : observe that the deep 

 layer is continuous on the bone with the fascia covering the Levator (black). 



The crus is firmly fastened by fibrous tissue to the everted surface : behind and 

 internal to it is the origin of Ischio-cavernosus and behind this Transversus perinei, 

 and all these must be between the blue and green lines. 



The extent to which these different areas can be traced backwards varies in 

 individual bones, and they are of course badly marked and much smaller in female 

 bones, but the plan of arrangement remains the same. The everted surface ends below 

 in a thick edge to the inner lip of which Colics' fascia is attached, while the outer 

 lip is for the fascia of the inner side of the thigh. 



No. 4, Fig. in, is a plan of the areas just described on the inner aspect of the 

 pubic ramus as shown by section : (a) surface of origin of obturator, (b) surface for 

 compressor, (c) everted surface. 



Now examine the area above the falciform ridge. The lower margin of the obturator 

 internus comes down to the ridge, for the muscle is a fairly thick one and makes a 

 mass that fills the slight concavity and has a convex lower margin. The parietal 

 fascia covers this part and is attached below it to the falciform process, making a 

 sheath (Alcock's canal) for the internal pudic vessels and nerve, which are thus carried 

 along the top of the falciform process and brought by it to the back of the triangular 

 ligament. They reach the sheath by crossing the inner or ischio-rectal aspect of the 

 obturator tendon. In No. 3 the vessels are shown piercing * the lining fascia above 

 the level of the ischial spine (S) ; thus, when they come in again below the spine they 

 are deep to the fascia and below the level of the pelvic floor. The figure also shows the 

 course of the canal. 



The extent of origin of the Levator from the pubis is variable : it may be as shown 

 in No. 2, Fig. in, or its level may be at the dotted line la in No. 3, or even higher. 

 There may be tendinous fibres causing roughnesses, but as a rule the rough area near 

 this region is for the Obturator, as in No. 2. The covering fasciae also reach the bone, 

 and thickenings in the visceral layer form the anterior pubo-prostatic ligaments, 

 which may apparently be sometimes indicated. 



Borders. 



Crest of Ilium. ObserveJ:he curved line formed by this crest, and notice that it 

 is thick and lipped in its anterior half or two-thirds. Certain areas can be found 

 on it without much difficulty. It ends behind at the posterior superior spine, and for 

 the first few inches in front of this it presents a blunt edge with sloping surfaces on 



* In the figure this is shown very schematically indeed, and no other vessels are represented : as a 

 matter of fact the sciatic and pudic vessels are very variable both in the position of their points of exit and 

 their relations to each other as they leave the cavity of the pelvis. 



It may be remarked also that the description of the pelvic fasciae given above is naturally very incom- 

 plete for instance, no mention is made of the double layer above the Levator ani, etc. But from the 

 present standpoint the account given is sufficient to enable the student to place the various structures 

 properly on the bone. 



