THE SKULL. 133 



horizontal, with bifid extremities in the cervical region. In the dorsal region, 

 they are directed obliquely above, assume almost a vertical direction in the 

 middle, and are horizontal below, as are also the spines of the lumbar vertebrae. 

 They are separated by considerable intervals in the loins, by narrower intervals 

 in the neck, and are closely approximated in the middle of the dorsal region. 

 Occasionally one of these processes deviates a little from the median line, a fact 

 to be remembered in practice, as irregularities of this sort are attendant also on 

 fractures or displacements of the spine. On either side of the spinous processes, 

 extending the whole length of the column, is the vertebral groove, formed by 

 the laminae in the cervical and lumbar regions, where it is shallow, and by the 

 laminas and transverse processes in the dorsal region, where it is deep and broad. 

 In the recent state, these grooves lodge the deep muscles of the back. External 

 to the vertebral grooves are the articular processes, and still more externally 

 the transverse processes. In the dorsal region, the latter processes stand back- 

 wards, on a plane considerably posterior to the same processes in the cervical 

 and lumbar regions. In the cervical region, the transverse processes are placed 

 in front of the articular processes, and between the intervertebral foramina. In 

 the lumbar, they are placed also in front of the articular processes, but behind 

 the intervertebral foramina. In the dorsal region, they are posterior both to 

 the articular processes and foramina. 



The lateral surfaces are separated from the posterior by the articular processes 

 in the cervical and lumbar regions, and by the transverse processes in the dorsal. 

 These surfaces present in front the sides of the bodies of the vertebrae, marked 

 in the dorsal region by the facets for articulation with the heads of the ribs. 

 More posteriorly are the intervertebral foramina, formed by the juxtaposition 

 of the intervertebral notches, oval in shape, smallest in the cervical and upper 

 part of the dorsal regions, and gradually increasing in size to the last lumbar. 

 They are situated between the transverse processes in the neck, and in front of 

 them in the back and loins, and transmit the spinal nerves. The base of the 

 vertical column is formed by the under surface of the body of the fifth lumbar 

 vertebra ; and the summit by the upper surface of the atlas. The vertebral canal 

 follows the different curves of the spine ; it is largest in those regions in which 

 the spine enjoys the greatest freedom of movement, as in the neck and loins, 

 where it is wide and triangular ; and narrow and rounded in the back, where 

 motion is more limited. 



THE SKULL. 



The Skull, or superior expansion of the vertebral column, is composed of four 

 vertebrae, the elementary parts of which are specially modified in form and size, 

 and almost immovably connected, for the reception of the brain, and special 

 organs of the senses. These vertebrae are the occipital, parietal, frontal, and 

 nasal. Descriptive anatomists, however, divide the skull into two parts, the 

 Cranium and the Face. The Cranium (xpavos, a helmet) is composed of eight bones : 

 viz., the occipital, two parietal, frontal, two temporal, sphenoid, and ethmoid. The 

 Face is composed ^fourteen bones: viz., the two nasal, two superior maxillary, 

 two lachrymal, two malar, two palate, two inferior turbinated, vomer, and inferior 

 maxilla,ry. The ossicula auditfis, the teeth, and Wormian bones, are not included 

 in this enumeration. 



