The orbit
- 14 March 2013
- book chapter
- Published by Oxford University Press (OUP)
Abstract
Some knowledge of the anatomy of the orbit is required by dental students and practitioners because it forms the upper part of the facial skeleton and some of the nerves and vessels supplying dental structures pass through it. Trauma to the middle third of the face, the upper facial skeleton, frequently involves the orbits and the structures they contain. Infections of the oral region occasionally spread to the orbit. In the following description, the emphasis is on those aspects of orbital anatomy of dental relevance; no description of the structure of the eyeball or the mechanisms of vision is included. The orbital cavities contain the eyeballs (globes), their associated muscles, vessels, nerves, the lacrimal apparatus, and a large amount of fat to cushion and protect the globes. Each cavity is pyramidal in shape. The base is the orbital opening on to the face; the roof, floor, and medial and lateral walls converge to the apex at the posterior aspect of the orbit. The long axis of the orbit from apex to surface runs forwards and laterally. The bones that form the orbit are illustrated in Figure 30.1 ; use the figure and a dried or model skull if possible as you read the following description. Most of the roof of the orbit is formed by the inferior surface of the orbital part of the frontal bone with a small posterior contribution from the lesser wing of the sphenoid ; this is pierced by the optic canal through which the optic nerve exits the orbit. The lateral wall is formed by the orbital surfaces of the zygomatic bone anteriorly and the greater wing of the sphenoid posteriorly. It separates the orbital cavity from the infratemporal fossa anteriorly and from the middle cranial fossa posteriorly. The floor of the orbit is occupied by the thin plate of bone forming the upper surface of the body of the maxilla ; this plate of bone is also the roof of the maxillary paranasal air sinus over most of its extent although the palatine bone forms a minute triangular area at the posteromedial corner.Keywords
This publication has 0 references indexed in Scilit: