900 A MANUAL OF ANATOMY 



of the fifth lumbar vertebra. The articulation between the bodies 

 of the fifth lumbar and first sacral vertebrae belongs to the class 

 amphiarthrosis, and the joints between the articular processes 

 belong to the class diarthrosis, and the subdivision arthrodia. In 

 addition to the foregoing ligaments there are two special ligaments, 

 called lateral lumbo-sacral and ilio-lumbar. The lateral lumbo- 

 sacral ligament, at either side, extends from the lower aspect of the 

 transverse process of the fifth lumbar vertebra anteriorly to the 

 upper surface of the ala of the sacrum at its anterior and outer 

 part close to the sacro-iliac articulation. It is somewhat fan-shaped, 

 and corresponds to the intertransverse ligaments of the lumbar 

 vertebrae, and the superior costo-transverse ligaments of the thoracic 

 region. The ilio-lumbar ligament extends from the tip of the 

 transverse process of the fifth lumbar vertebra to the inner lip of 

 the iliac crest, where it is attached for about 2 inches above the 

 back part of the iliac fossa. It is triangular, and its direction is 

 outwards and slightly backwards. It is closely associated with 

 the lower part of the anterior lamina of the lumbar aponeurosis. 



Arterial Supply. — Ilio-lumbar and superior lateral sacral arteries. 



Nerve-supply. — Fourth and fifth lumbar nerves, and sympathetic 

 filaments. 



Movements. — Flexion, extension, and lateral movements between 

 the opposed bodies, and gliding and rotation between the articular 

 processes. 



Sacro-coceygeal Articulation. — This belongs to the class amphi- 

 arthrosis. The bony elements are the fifth sacral and first coccygeal 

 vertebrae. The opposed surfaces are transversely oval, and are 

 separated by an intervertebral disc, unless in advanced life, when 

 ankylosis takes place, this occurrence being earlier and more fre- 

 quent in the male than in the female. The ligaments are as follows : 

 anterior and posterior sacro-coccygeal, which are continuations of 

 the anterior and posterior common ligaments of the bodies of the 

 vertebrae ; supracornual, which pass between the sacral and coccygeal 

 cornua ; and intertransverse or lateral, which pass between the in- 

 ferior lateral angles of the sacrum and the transverse processes of 

 the first coccygeal vertebra. The latter ligament is liable to become 

 ossified. 



Arterial Supply. — Inferior lateral and middle sacral arteries. 



Nerve-supply. — Lower two sacral, and coccygeal, nerves. 



Movements. — Forward and backward movements are allowed.. 



Intercoccygeal Articulations. — These only exist prior to middle 

 life. The union between the coccygeal segments is effected by 

 intervertebral discs, and anterior and posterior ligaments. The 

 adjacent fibres of the great and small sacro-sciatic ligaments serve 

 as lateral ligaments. 



Sacro-iliac Articulation. — This belongs to the class amphiarthrosis. 

 The bony elements are the auricular and ligamentous surfaces of 

 the sacrum and ilium. The cartilage of the auricular surface is 

 about yV inch thick, and it may be a single plate for both surfaces, 



