OSTEOLOGY AND SYNDESMOLOGY. 25 



arise from the edges of tlie foramen magnum, and are inserted into the 

 upper border of the atlas before and behind its obhque processes. The 

 lateral ligaments extend as strong cords from the transverse processes of the 

 occipital bone to those of the atlas. 



Between the atlas and occiput, as already remarked, scarcely any motion 

 but that of flexion and extension can occur. The turning of the head, or 

 the horizontal motion, takes place between the first and second vertebras 

 (the atlas and epistropheus). To this end, the articular extremity of the 

 odontoid process rests on a depression on the posterior border of the ante- 

 rior arch of the atlas. It is held in this position by a capsular ligament, 

 but for the sake of greater security a strong, straight ligament (the trans- 

 versal) extends behind it from one side of the atlas to the other. The 

 neck of the odontoid process is thus inclosed in a circular collar, formed by 

 the arch of the atlas in front and the transverse hgament behind, in which 

 it can rotate like a pivot, being held most securely in its place {pi. 12-i, 

 Hg. 7 '). The importance of this ligament is very great ; in cases where it 

 has become softened by disease, and ruptured, death has been instanta- 

 neous ; the head falling forward and the odontoid process projecting back- 

 ward, has either compressed or pierced the medulla oblongata. An addi- 

 tional security against dislocation is furnished by the moderator or check 

 ligaments, lig. Suspensorium dentis epistrophei {ßg. 7 '' '^), which arise one 

 from each side of the odontoid process, and are inserted into a depression 

 on the inner side of each occipital condyle. The two ligaments are usually 

 united by a fasciculus which passes above the summit of the odontoid 

 process. In addition we find a ligament, the middle occipito-axoid or ap)pa- 

 ratus ligamentosus {fg. 5 '), extending from the inner surface of the basilar 

 process of the occipital bone beneath the dura mater, and passing through 

 the foramen occipitale, to be inserted into the superior part of the trans- 

 verse ligament of the atlas, and below this into the bodies of the second, 

 third, and fourth vertebrae. 



In addition to the ligament extending between the head and first and 

 second cervical vertebrae, there are others which either extend continu- 

 ously along the entire spine, or are repeated between each contiguous pair 

 of vertebras. These may be distinguished into two sets : those which unite 

 the bodies, and those uniting the processes. The first comprise the ante- 

 rior and posterior common vertebral ligaments and the intervertebral fibro- 

 cartilages or ligaments ; the second set include the capsules and synovial 

 membranes of the oblique processes, the infra-spinous or yellow ligaments, 

 the inter-spinous, the supra-spinous, and the inter-transverse. The bodies 

 of the vertebrae are united by an anterior, a posterior, and an intervertebral 

 ligament. 



The anterior vertebral ligament {pi. 124:, fg. 4") is a strong band of fibres 

 extending from the atlas to the sacrum along the anterior face of the spine, 

 and adhering strongly to the bones, particularly to their edges and to the 

 intervertebral substances. Its object is to attach the vertebrsß together, to 

 strengthen the intervertebral ligaments, and to oppose excessive extension 

 of the column. 



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