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.

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