CHAPTER III 



BONES AND ARTICULATIONS OF THE 

 SPINAL COLUMN AND TRUNK 



The bones of the spinal column are 

 twenty-six in number. They are irregular 

 and are arranged as follows, from above 

 downward: 



f 7 cervical in the neck. 



24 separate vertebrae | 12 thoracic in the back. 



I 5 lumbar in the loins. 



i sacrum, 

 i coccyx. 



in the pelvis. 



A vertebra consists of a body and an 

 arch, joined together to form a ring of 

 bone with a space enclosed called the 

 vertebral foramen, which is occupied by the 

 spinal cord. The bodies are composed of 

 spongy bone, placed one above the other 

 and held together by discs of fibrocartilage 

 between them. In this way the solid and 

 flexible portion of the spine is constructed. 



The arch consists of two roots next to the 

 body, and two lamina which meet at the 

 back. There are seven processes on the 

 arch of each vertebra four articular (two 

 to form joints with the bone above, two 

 for the bone below); two transverse (pro- 

 jecting from the sides), and one spinous 

 which projects backward. The row of 

 spinous processes is felt by passing the ringer 

 down the back in the median line; that of 

 the seventh vertebra is easily seen, and 

 this bone is called the vertebra prominens. 



39 



FIG. 3 i. VERTEBRAL 

 COLUMN, LATERAL ASPECT. 



1-7, Cervical vertebrae; 

 8-19, dorsal vertebrae; 20- 

 24, lumbar vertebras; A, A, 

 spinous processes; B, B, 

 articular facets of trans- 

 verse processes of first ten 

 dorsal vertebras; C, auricu- 

 lar surface of sacrum; D, 

 D, foramina in transverse 

 processes of cervical verte- 

 bras. (Sappey.) 



