5O ANATOMY AND PHYSIOLOGY 



the coccyx attached to its apex, and thus the pelvic girdle is formed, 

 usually called the pelvis (or basin). These joints have no cavity, 

 and are only slightly movable, or yielding. There is a distinct 

 disc of nbro-cartilage at the pubic symphysis. 



Greater sacro- 

 sciatic ligament 



Lesser sacro-sci- 

 atic ligament 



Tendon of biceps muscle 



FIG. 45. GREATER AND LESSER SACRO-SCIATIC LIGAMENTS AND FORAMINA. (Morris.) 



Obstetric note. The pubic symphysis and the sacro-iliac symphysis 

 probably soften slightly during pregnancy. The sacro-coccygeal joint has 

 limited motion until middle life advances, when it may become fixed. 



Sacro-sciatic ligaments (Fig. 45). Two strong bands are stretched 

 between the sacrum and the ischium. They have no connection with any 

 joints but are called the greater and the lesser sacro-sciatic ligaments. The 

 greater (ligamentum sacro-tuberosum) extends from the borders of the sacrum 

 and coccyx to the tuber osity of the ischium; the lesser (ligamentum sacro- 

 spinosum) is placed immediately in front of it, extending from the sacrum 

 and coccyx to the spine of the ischium. Thus are formed two foramina with 

 the lesser ligament between them, the one above being called the greater 

 sciatic foramen, and the one below the lesser sciatic foramen. (The sciatic 

 nerves pass through the greater foramen.) 



Poupart's ligament, or the inguinal ligament, may be felt like 

 a tight cord stretched between the spine of the ilium and the spine 

 of the pubis "from spine to spine." 



