THE HUMAN SKELETON 
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2. Comparative Study of Other Regions of the Vertebral 
Column. 
Study these as illustrations of regional differentiation, using 
the parts of the nearest thoracic segment as a basis for interpreting 
the vertebrae of other regions. 
A Typical Cervical Vertebra (3rd to 5th).- —Study as in case of 
the lumbar vertebra; note the presence of the foramina of the 
transverse processes and seek an explanation of their formation 
by comparison with the structure of an anterior thoracic vertebra 
and the ribs articulated with it. Draw an anterior view. 
The Atlas and Epistropheus. —Study these carefully for 
specializations due to their function of supporting the skull; note 
in the atlas the absence of the body, and the consequent ring-like 
form of the bone, with dorsal and ventral arches, the latter forming 
an articulation with the tooth of the epistropheus; peculiarities 
in shape and position of articular surfaces (a) on the atlas for 
articulation with the occipital condyles of the skull, (b) on both 
atlas and epistropheus for articulation with each other; note the 
direction and extent of the motion of the head made possible by 
these articulations, and compare this with the range of movement 
of other parts of the vertebral column. Draw an anterior view 
of atlas , also a lateral view of both atlas and epistropheus , the bones 
slightly separated to show their complete shape. 
A Typical Lumbar Vertebra. —Note the peculiarities in form 
and size of body, arch, and processes. Compare with the various 
thoracic vertebrae as to the slant of processes and the number and 
position of articular surfaces. Draw an anterior view. 
The Sacrum. —Note the number and relation of fused com¬ 
ponent parts, and find a reason for the fusion; lateral masses 
formed by the fused ribs; the continuation of the vertebral canal; 
foramina in three series, intervertebral, dorsal, and ventral, and 
their relation to the component sacral vertebrae and rib elements; 
auricular surfaces for the attachment of the pelvic girdle. Draw a 
dorsal or a ventral view. 
The Coccyx. —Note the number of component parts and the 
extent to which these are fused (cf. with parts of a typical vertebra 
and with the caudal vertebrae of other mammals). Add the 
coccyx to the drawing of the sacrum. 
