. An introduction to the osteology of the mammalia . s (Fig. 9) is little more than anoval ring, thickened on each side into the so-called lateralmass/ which bears an articular surface before and anterior surfaces are very large, elongated from abovedownwards, and hollowed for the reception of the condyles ofthe occiput. The posterior articular surfaces are subcircular D 34 CERVICAL VERTEBRA. [CHAP. flattened, or slightly-concave. The transverse processes areshort, stout, and perforated; the arch presents scarcely arudiment of a spinous process. On its anterior edge im-mediately abo
. An introduction to the osteology of the mammalia . s (Fig. 9) is little more than anoval ring, thickened on each side into the so-called lateralmass/ which bears an articular surface before and anterior surfaces are very large, elongated from abovedownwards, and hollowed for the reception of the condyles ofthe occiput. The posterior articular surfaces are subcircular D 34 CERVICAL VERTEBRA. [CHAP. flattened, or slightly-concave. The transverse processes areshort, stout, and perforated; the arch presents scarcely arudiment of a spinous process. On its anterior edge im-mediately above the articular surface is a deep notch orgroove (g) of some importance, as it corresponds with theslight notch in front of the pedicle in other vertebrae, whichcontributes with the deeper notch in the hinder border ofthe pedicle of the preceding vertebra to form the inter-vertebral foramen for the exit of a spinal nerve, and because,occasionally in man, and constantly in many animals, it isconverted by a bridge of bone into a canal, through which. to, FIG. 9.—Human atlas, young, showing development, \. ia inferior arch ; as articularsurface for occiput; t transverse process ; g groove for first spinal nerve andvertebral artery. the first cervical (or suboccipitat) nerve passes out. Theinferior arch of the atlas (ia) differs entirely from the bodiesof the other vertebrae, being a simple, depressed, slightlycurved bar of bone, with a smooth facet on its neural orupper surface, for articulation with the odontoid process ofthe axis. The second cervical vertebra, axis, epistrophens, or vertebradsntata (Fig. 10), has a body terminating anteriorly in alarge subconical median projection, the odontoid process(0), which is received into, and articulates with, the con-cavity of the inferior arch of the atlas. It is retained in IV.] MAN. 35 its place by means of a strong transverse ligament passingbetween the lateral masses of that bone, and separating itscanal into an upper or neural
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbones, bookyear1885
