LIGAMENTS OF THE PELVIS. 273 



3. Ligaments connecting the Sacrum and Os Coccygis. 



A general covering is sent down from the ligaments of the 

 os sacrum, which spreads over and connects the different pieces 

 of the os coccygis together, allowing considerable motion, as 

 already mentioned, in the description of this bone. This 

 forms what is called the anterior and posterior coccygeal lig- 

 aments. 



The posterior longitudinal ligaments of the os coccygis 

 descend from those upon the dorsum of the os sacrum, to be 

 fixed to the back part of the os coccygis. The ligaments of 

 this bone prevent it from being pulled too much forwards by 

 the action of the coccygeus muscle, and they restore the bone 

 to its natural situation, after the muscle has ceased to act. 



4. Ligaments connecting the Ossa Pubis. 



A ligamentous Jibro-cartilage, resembling in structure the 

 intervertebral substance, unites the two ossa pubis so firmly 

 together at their symphysis as to admit of no motion, excepting 

 in the state of pregnancy, when it is frequently found to be so 

 much softened as to yield a little in the time of delivery. ^ 



There are a few transverse ligamentous fibres on the front 

 part of the symphysis pubis, called the anterior pubic ligament. 

 These interlace in front of the symphysis. 

 There are also a few irregular fibres on the posterior face 

 of the articulation crossing from bone to bone, called the poste- 

 rior pubic ligament. 



The sub, or interpubic ligament occupies the summit of the 

 arch of the pubis. It is about half an inch in breadth, and 

 passes from the crus of the pubis of one side to that of the 

 other. 



A thick strong band of fibres is found crossing from bone to 

 bone, on their superior face, and filling up the inequalities 

 which exist there ; it is called the superior pubic ligament. 



The obturator membrane, or ligament of the foramen thy- 

 roideum, adheres to the margin of the foramen thyroideum, and 

 fills the whole of that opening, excepting the oblique notch at 



