11-28. THE ORBIT
The orbit is the cavity in the upper facial skull which contains the
eyeball and its adnexa. The orbit is open anteriorly.
a. The floor of the orbit is generally horizontal. Its medial wall is
generally vertical and straight from front to back. Since the lateral wall and roof
converge to the rear, the orbit is a conelike cavity.
b. In the facial skull, the orbit is surrounded by a number of specific
spaces. Superiorly, the roof of the orbit is also the floor of the anterior cranial
cavity, where the frontal portion of the brain is. Just medial to the medial wall are the
structures of the nasal chamber. Inferiorly, the floor of the orbit is also the roof of
the maxillary sinus. Laterally, the wall of the orbit is the inner wall of the temporal
fossa, a depression on each side of the skull where a fan-shaped chewing muscle
(temporalis M.) is attached.