Structure
The lacrimal gland is composed of two parts, the orbital and palpebral parts that are continuous with each other posterolaterally around the levator palpebrae superioris muscle. The gland itself is lobulated exocrine gland. It contains the secretory unit, the acini, that discharge their aqueous product into a central lumen. The numerous lumens are continuous with an intercalated duct. Myoepithelium also surrounds the acini and ducts, which provide a mechanical force for the expulsion of tears from the gland. The lacrimal gland has up to twelve ducts that discharge tears into the conjunctival sac.
The lacrimal gland receives its blood supply from the lacrimal branch of the ophthalmic artery, with contributions from the infraorbital artery. Blood is drained via the superior ophthalmic vein.
Sensory innervation of the lacrimal gland is provided by the ophthalmic nerve (CNV1). Secretomotor postganglionic parasympathetic innervation of the lacrimal gland is received from the pterygopalatine ganglion. These fibers reach the gland via the zygomatic and lacrimal branches of the maxillary nerve (CNV2) or directly from the ganglion. The superior cervical ganglion provides sympathetic fibers to the lacrimal gland.
Related parts of the anatomy
Key Features & Anatomical Relations
The larger orbital part of the lacrimal gland (about the size and shape of an almond) is contained within a shallow fossa on the medial aspect of the frontal bone to which it is connected to. It lies above the levator palpebrae superioris and the lateral rectus muscles. Its inferior surface is attached to the fascia of levator palpebrae superioris; its posterior border is attached to the dense orbital fat; and its anterior border is in contact with the orbital septum (palpebral fascia).
The smaller palpebral part of the lacrimal gland extends inferior to the levator palpebrae superioris and into the lateral part of the upper eyelid. It is attached to the superior conjunctival fornix.
Function
The lacrimal gland is responsible for producing the aqueous component of tears. This is a watery secretion containing several proteins, such as lysozymes and immunoglobulin A, that protect the surface of the eye from infection, while maintaining the epithelial surface of the eye.
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Lacrimal Gland
The lacrimal gland is a tubulo-acinar exocrine gland composed of acinar, ductal, and myoepithelial cells.
