. .it The upper figure shows the sacro-coccygeal region from behind. On the left side are the areas for Multilidus, great 

 su.iiir ligament, posterior sacro-iliac ligs. (1. 1C), and articular surface (ART). On the right the Multilnlus h.i 

 altogether removed ; it is covered in by the mass of Krcctor spin.T, which is arising from the posterior sacro-iliac liga- 

 ments and the adjacent part of the ilium. These post-vertebral muscles are shut in by a thick aponeurosis which is 

 fastened to the spinous ridge and to the iliac crest externally : it is a compound of post-vertebral aponeurosis and 

 aponeurotic origin of Latissimus dorsi, and its iliac attachment is shown by interrupted lines. It is fused below with the great 

 sciatic ligament and is shown cut here ; this continuity with the ligament explains how the Glutcus maximus and the 

 ligament obtain origin from the lower part of the sacrum. Multilidus docs not extend down to the lower part of the boii' 

 here the ligamentous fibres are attached to the sacrum and cover in the hiatus sacralis centrally, with the nerves, etc., lying in 

 it. In the drawing the hiatus and coccyx have been exposed by removal of this covering of fibrous tissue. It should be 

 noted that Multifidus really arises from the surface of a fibrous sheet which is attached to points on the bone, and not dim tlv 

 from the bone itself; the junction between tin- nerves takes place between this sheet and the bone. The lower left ligurr 

 -li'ius a section through the middle line of the sacrum and coccyx, illustrating their relations with the rectum and 

 peritoneum. The remaining figure is a scheme of a section across the pelvis to show how the sacrum is " suspended 

 between the innominate bones by the posterior sacro-iliac ligaments, which must, therefore, be exceedingly thick and s> 

 Behind these the post- vertebral muscles fill up the deep fossa between the posterior parts of the iliac crests and the sacral 

 spines. Compare this with the first figure LD, plane of Latiss. dorsi fused with post-vertebral aponeurosis. 



