PHYSIOLOGY FOR BEGINNERS 



firmly attached to the body of the vertebra on each side 

 of it, so that it serves not only as a cushion between them, 

 but binds them together. The arch of one vertebra touches 

 the arch of the next above and below at a smooth prominence 

 on each side, and the two are united together by liga- 

 ments at these 

 spots, forming a 

 double row of 

 joints. There are 

 also ^^nents 

 passing^Bm ver- 

 tebra to vertebra 

 down the front 

 and back of the 



F.G.I.. -A dorsal vertebra. bodleS f the 



A, side view, right side ; B, view from above ; b, body ; tr, vertebrae, as well 



transverse processes; sp, spinous process; ar, place on as ligaments COn- 



the arch for articulation with vertebra above ; A', place nectingthcarches 



on body for articulation of end of rib; n, canal for an( j processes of 

 spinal cord. 



one vertebra to 



the next, so that these are strongly bound together into a firm 

 but slightly flexible column. 



Since the arches of the vertebras lie over one another, they 

 form together a canal, and in this the spinal cord lies, so that not 

 only do the bodies of the vertebrae united together form a 

 support for the trunk, but also the arches form a protection for 

 the spinal cord. The spinal column is not straight ; it is arched 

 forwards in the cervical region, backwards in the dorsal region, 

 forwards again in the lumbar region, and, lastly, backwards 

 in the sacral region. These curves give grace and elasticity to 

 the trunk, and allow the back to be bent to a certain extent 

 forwards and backwards. The spinal column has also a little 

 play from side to side, and will even allow a very little twisting 

 movement at the joints between the vertebra . 



The first cervical vertebra is called the atlas, and differs 

 in form from the other vertebrae. It is ring-shaped, and without 

 any proper body, only the anterior part of the ring correspond- 

 ing in position to the body of a typical vertebra. The second 

 cervical vertebra, called the axis, is also peculiar, for its 

 body carries a process which goes into the front part of the 



