546 



DISSECTION OF THE PELVIS. 



LIGAMENTS OF THE INNOMINATE BONES (fig. 191). The innominate 

 bones are united in front, at the pubic symphysis, by an interposed piece 

 of cartilage and special ligaments ; and behind, each is connected with 

 the transverse process of the last lumbar vertebra by a separate band (ilio- 

 lumbar). In the centre of the bone is a membranous structure closing the 

 thyroid aperture. 



The ilio-lumbar or ilio-vertebral ligament is triangular in form and is 

 divided into fasciculi. Internally it is attached to the tip of the trans- 

 verse process of the last lumbar vertebra ; externally the fibres spread out, 



Fig. 191. 



a. Anterior ligament of the symphysis ; d, 

 inferior, and c, cartilage of the sym- 

 physis. with a slit in the middle. 



6. Obturator membrane. 



e. Surface of the acetabulum covered with 

 cartilage. 



/. Fatty substance in the acetabulum. 



g. Cotyloid ligament, which is cut where 

 it forms part of the transverse band 

 over the notch. 



h. Deep part of the ligament over the coty- 

 loid notch. 



LIGAMENTS OF THE SYMPHYSIS PUBIS, THYROID HOLE, AND ACETABULUM. 



and are inserted into the iliac-crest for about an inch, opposite the poste- 

 rior part of the iliac fossa. To the upper border of the ligament the fascia 

 lumborum is attached ; its posterior surface is covered by the quadratus 

 lumborum, and its anterior by the iliacus muscles. 



The thin obturator membrane (fig. 191, b) closes almost entirely the 

 thyroid foramen, and is composed of fibres crossing in different directions. 

 It is attached to the bony margin of the foramen, except above where the 

 obturator vessels pass through ; and towards the lower part of the aperture 

 it is connected to the pelvic aspect of the hip-bone. The surfaces of the 

 ligament give attachment to the obturator muscles. Branches of the ob- 

 turator vessels and nerve perforate it. 



PUBIC ARTICULATION (fig. 191, a) (symphysis pubis). The oval pubic 

 surfaces of the hip bones are united by cartilage, and by fibres in front 

 of, and above the bones : they are also connected by a strong subpubic 

 ligament. 



The anterior pubic ligament (fig. 191, a) is very strong and is formed 

 of different layers of fibres. The superficial are oblique, and cross one 

 another, joining with the aponeurosis of the external oblique muscle of 



