Anatomy

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The venous drainage of the orbit is primarily through the superior and inferior ophthalmic veins, into which drain the vortex veins, the anterior ciliary veins, and the central retinal vein.

The ophthalmic veins communicate with the cavernous sinus via the superior orbital fissure and the pterygoid venous plexus via the inferior orbital fissure.

The superior ophthalmic vein is initially formed from the supraorbital and supratrochlear veins and from a branch of the angular vein, all of which drain the skin of the periorbital region. This provides a direct communication between the skin of the face and the cavernous sinus, thus forming the basis of the potentially lethal cavernous sinus thrombosis secondary to superficial infection of the periorbital skin.

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The Extraocular Muscles

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Rectus Muscles

originate at a common ring tendon (annulus of Zinn) .

Function

distances from the limbus

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Oblique Muscles

control primarily torsional movement and, to a lesser extent, upward and downward movement of the globe

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The superior oblique is the longest and thinnest of the ocular muscles.

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The inferior oblique muscle originates from the nasal side of the orbital wall just behind the inferior orbital rim and lateral to the nasolacrimal duct.

The insertion is into the posterotemporal segment of the globe and just over the macular area.

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Nerve Supply

The oculomotor nerve (III) innervates the medial, inferior, and superior rectus muscles and the inferior oblique muscle.

The abducens nerve (VI) innervates the lateral rectus muscle;

the trochlear nerve (IV) innervates the superior oblique muscle.

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The Conjunctiva