134 LIGAMENTS OF THE UPPER EXTREMITY. 



The ligaments connecting the different pieces of the coccyx consist 

 of a few scattered anterior and posterior fibres, and a thin disc of inter- 

 osseous cartilage ; they exist only in the young subject, in the adult 

 the pieces become ossified. 



4. Between tfie Ossa Pubis. The anterior pubic ligament is com- 

 posed of ligamentous fibres, which pass obliquely across the union 

 of the two bones from side to side, and form an interlacement in front 

 of the sympbjsis. 



The posterior pubic ligament consists of a few irregular fibres uniting 

 the pubic bones posteriorly. 



The superior pubic ligament is a thick band of fibres connecting the 

 angles of the pubic bones superiorly, and filling the inequalities upon 

 the surface of the bones. 



The sub-pubic ligament is a thick arch of fibres connecting the two 

 bones inferiorly, and forming the upper boundary of the pubic arch. 



The interosseous fibro-cartilage unites the two surfaces of the pubic 

 bones, in the same manner as the intervertebral substance connects 

 the bodies of the vertebrae. It resembles the intervertebral substance 

 also in being composed of oblique fibres disposed in concentric layers, 

 which are more dense towards the surface than near the centre. It is 

 thick in front, and thin behind. A synovial membrane is some- 

 times found in the posterior half of the articulation. 



This articulation becomes movable towards the latter term of preg- 

 nancy, and admits of a slight degree of separation of its surfaces. 



The obturator ligament or membrane is not a ligament of articula- 

 tion, but simply a tendino-fibrous membrane stretched across the ob- 

 turator foramen. It gives attachment by its surfaces, to the two obtu- 

 rator muscles, and leaves a space in the upper part of the foramen, for 

 the passage of the obturator vessels and nerve. 



The numerous vacuities in the walls of the pelvis, and their closure 

 by ligamentous structures, as in the case of the sacro-ischiatic fissures 

 and obturator foramina, serve to diminish very materially the pressure 

 on the soft parts during the passage of the head of the fetus through 

 the pelvis in parturition. 



LIGAMENTS OF THE UPPER EXTREMITY. 



The Ligaments of the upper extremity may be arranged in the order 

 of the articulations between the different bones ; they are, the 



1. Sterno-clavicular articulation. 



2. Scapulo-clavicular articulation. 



3. Ligaments of the scapula. 



4. Shoulder joint. 



5. Elbow joint. 



6. Radio-ulnar articulation. 



7. Wrist joint. 



