Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

    283/384 (page 271)
    The most distinctive character of this bone is the absence of a body, the place of the body being occupied by a groove or space in its anterior arch, into which the odontoid process of the axis is fitted. This groove is separated from the vertebral canal by the transverse ligament, which passes behind the process, strap- ping it into its place. The Axis, or second cervical vertebra, forms the pivot on which the head turns, or performs its horizontal or lateral rotating movement; hence it is termed the axis vertebra. (See Fig. 57-) Fig. 57.—Axis, or Dentate Vertebra. I. Body. 2. Odontoid process. 3. Ar- ticulating surface. 4. Transverse process. 5. Lateral notch. 6. Foramen for vertebral artery. 7. Spinal process. Its most distinctive character is the dentate or odontoid process, which consists of a strong prominent tooth-like process rising perpendicularly from the upper part of the body of the bone. This process fits into a corresponding groove in the front arch of the atlas, forming the pivot on which it rotates. It is retained in its place in the atlas by small ligaments. These small ligaments are, especially in children, easily stretched or tom, and the bones consequently displaced, the result of which is instant death. Great care should therefore always be taken in handling the heads and necks of children—as, for instance, in drying them after bathing, washing, &c.,—lest serious consequences should follow. Structure of a Vertebra.—A vertebra usually comprises Fig. 58.—Side of a Vertebra. I, 2. Lateral notches, 3. Body. 4, 4. Articulating surfaces to re- ceive heads of ribs, 7. Transverse process. 8. Articular cavity for tubercle of rib. 9. Spinous pro- cess. 10. Tuberosity of spinous process for insertion of muscle.