74 OSTEOLOGY 



twenty-six to twenty-seven inches measured along the 

 curved anterior surface of the column. The cervical 

 part measures about five, the thoracic about eleven or 

 twelve, the lumbar about seven inches, and the sacrum 

 and coccyx the remainder. 



Viewed from the side it presents several curves. 

 The cervical curve commences at the odontoid process 

 of the second vertebra, and ends at the middle of the 

 second thoracic ; it is convex in front, but not as marked 

 as the other curves. The thoracic curve is concave 

 forward, commences at the middle of the second thor- 

 acic, and ends at the middle of the twelfth thoracic. 

 The lumbar curve, commences at the middle of the 

 twelfth thoracic and ends at the sacrovertebral angle 

 (about the junction of the sacrum with the fifth lum- 

 bar vertebra). It is convex in front; the convexity 

 being more marked in the lower three lumbar verte- 

 brae. These curves and convexities are formed by the 

 bodies of the vertebrae. While the posterior aspect is 

 formed by the extending spinous processes which usually 

 can be felt underneath the skin and fascia, no matter 

 how stout the individual. Laterally the column 

 presents the transverse processes. The spinal cord, 

 membranes, origin of spinal nerves, and blood-supply 

 are within the spinal canal formed by the inter- 

 vertebral fibrocartilage, body, and arched lamina of 

 the vertebrae; the latter fusing posteriorly, complete 

 its boundaries. Posteriorly, the spinous processes 

 occupy the median line, in a depression known as the 

 vertebral groove running along the middle of the 

 back. In the cervical region the processes are short 

 and bifid, sloping backward and a little downward. 

 The seventh cervical is the most prominent and can 

 always be seen and felt beneath the skin, therefore its 

 name vertebra prominens. The thoracic processes are 

 oblique above, more oblique in the middle, and below 

 are nearly horizontal; in the lumbar region they are 

 horizontal. The transverse processes of the atlas are 



