_Description._—The atlas is the smallest of the cervical vertebræ and is ring-shaped. The anterior articular surface, half-moon in shape, forms a deep articular cavity. The joint, called a ball-and-socket joint, makes possible movements in all directions. The condyle of the occiput also touches an articular end of the odontoid process of the axis, or second cervical vertebra. Posteriorly there projects from the atlas two small lateral wings possessing articular facets which articulate with similar facets on the lateral wings of the axis. Posteriorly the body of the atlas is also provided with an articular surface which articulates with a similar surface on the anterior portion of the body of the axis. =The Axis.= _Location._—The axis is the second cervical vertebra. It articulates anteriorly with the atlas, and by a facet on the extreme anterior end of the odontoid process, with the condyle of the occipital bone. Posteriorly it articulates with the third cervical vertebra. _Description._—The body of the axis is short. The upper anterior portion of the body of the axis is provided with a tooth-like process called the _odontoid process_. There are two anterior lateral wings provided with small articular facets which articulate with similar facets of the atlas. The anterior surface of the body of the axis forms a true articulation with the body of the atlas. The axis is provided with a _superior_ and an _inferior spine_. There are two posterior articular processes which articulate with the prezygapophyses, or anterior articular processes, of the third cervical vertebra. The posterior part of the body of the axis forms a true articulation with the body of the third cervical vertebra. =Other Cervical Vertebræ.=—Beginning with the axis, the body of which is relatively short, the body of each succeeding vertebra is longer than that of the preceding. The articulations of each vertebra with adjoining vertebræ are effected by means of diarthrodial facets, convex in one direction and concave in the other. [Illustration: FIG. 10.—_A._ Diagram of three first dorsal vertebræ and scapular arch-side view. _B._ Diagram of section through the hemal arch. _A._ 1, First dorsal segment. 2, Second. 3, Third. 4 and 5, Hemal arches. 6, The pleurapophyses or floating ribs. 7, The third pleurapophyses or dorsal vertebral rib articulating with the hemapophysis or sternal rib, 8, and this in turn with the wing of the sternum form a hemal arch. 9, The sternum. 10, Intervertebral foramen through which the nerves pass. 11, Articulation with the body of vertebra parapophyses. 12, Articulation with transverse process or diapophyses. 13, Oblique process or zygapophysis. 14, The epipleural appendage.