996 THE DIGESTIVE SYSTEM. 
The pelvic cavity is bounded in front and at the sides by the portions of the in- 
nominate bones below the level of the iliopectineal lines. These bony walls are partly 
clothed, in front and laterally, by the obturator internus muscles, and internal to these 
by the parietal portion of the pelvic fascia, as low down as the white line. ‘The posterior 
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Fra. 671.—THe Front or THE Bopy, showing the subdivisions of the abdominal cavity and the position ot 
the chief viscera. (From a photograph of the body represented in the preceding figure.) The viscera in 
Fig. 670 have been traced in red on this figure. ‘The photographs for these two figures and for Fig. 675 
were taken from the same body, under precisely similar conditions ; consequently the relations of the 
deeper parts to the surface are correctly obtained by superimposing the pictures as in this illustration. 
The liver occupies a slightly lower position than usual. 
wall is formed by the front of the sacrum, covered on each side by the pyriformis 
muscle. This wall (as represented by the pyriformis muscles) meets the lateral wall 
at the anterior border of the great sciatic foramen ; through this foramen the pyriformis 
passes out, thus closing up what would otherwise be a large aperture in the parietes of 
the cavity. The floor is composed of the two pairs of muscles which form the pelvic 
diaphragm, namely, the levatores ani and coceygei—covered by the visceral layer of the 
