Anatomy

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Lymphatics from the lateral segment of the lids run into the preauricular and parotid nodes. Lymphatics draining the medial side of the lids empty into the submandibular lymph nodes

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The Lacrimal Apparatus

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consists of the lacrimal gland, the accessory lacrimal glands, the canaliculi, the lacrimal sac.

The accessory lacrimal glands (glands of Krause and Wolfring) are located in the substantia propria of the palpebral conjunctiva

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The blood supply of the lacrimal gland is derived from the lacrimal artery.

The nerve supply to the lacrimal gland is by (1) the lacrimal nerve (sensory), a branch of the trigeminal first division; (2) the great superficial petrosal nerve (secretory), which comes from the superior salivary nucleus; and (3) sympathetic nerves accompanying the lacrimal artery and the lacrimal nerve

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The angular vein and artery lie just deep to the skin, 8 mm to the nasal side of the inner canthus.

Skin incisions made in surgical procedures on the lacrimal sac should always be placed 2–3 mm to the nasal side of the inner canthus to avoid these vessels.

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The Orbit

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a pyramid of four walls that converge posteriorly. The medial walls of the right and left orbit parallel and are separated by the nose. In each orbit, the lateral and medial walls form an angle of 45 degrees, which results in a right angle between the two lateral walls. The orbit is compared to the shape of a pear, with the optic nerve representing its stem.

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volume of the adult orbit :30 mL

eyeball occupies only about one-fifth of the space. Fat and muscle account for the bulk of the remainder.

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The anterior limit of the orbital cavity is the orbital septum, which acts as a barrier between the eyelids and orbit

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frontal sinus above, the maxillary sinus below, and the ethoid and sphenoid sinuses medially.