THE SKELETON 



kind of curved wedge, formed by the next five vertebrae fused 

 together into one firm mass of bone. This wedge is called the 

 sacrum (Lat. sacred), and 

 to its lowest and narrowest 

 end is attached the coccyx 

 (Lat. a cuckoo), which 

 consists of four very im- 

 perfectly formed vertebrae, 

 corresponding with the tail 

 in other animals. 



The sides of the sa- 

 crum are united with the 

 two large hip-bones, and 

 form a basin-like cavity 

 called the pelvis (Lat. a 

 basin). These will be more 

 conveniently described with 

 the bones of the limbs. 



In order to understand 

 clearly the construction 

 and uses of the vertebral 

 column it will be neces- 

 sary to notice the form 

 of a single vertebra ; and 

 though the vertebrae differ 

 from each other in detail, 

 yet all are constructed on 

 the same plan, and a gene- 

 ral description of one will 

 answer for all. 



A vertebra consists of 

 a bony body from which 

 spring two arches, the 

 latter uniting in such a 

 manner as to form a kind 

 of ring which encloses the 

 spinal cavity. From the 

 outer circumference of this 

 bony ring are given off 

 three projections, which are 

 called processes. The body 

 is the front portion of the 

 vertebra, and the process 

 which projects from the 

 arch, exactly opposite the 



Fig. 9. The Verte- 

 bral Column, viewed 

 from the left side. 



Fig. io. TheVerte. 

 bral Column, viewed 

 from behind. 



C i, first cervical vertebra ; D i, first dorsal vertebra ; 

 L i, first lumbar vertebra ; S i, first sacral vertebra; 

 Co i, first coccygeal vertebra. 



