Lacrimal

Lacrimal, from the Latin lacrima meaning tear, is an anatomical term that relates to tears and to structures that produce, secrete, and drain them, as well as to the lacrimal bone. In clinical use, lacrimal denotes the lacrimal apparatus and the related anatomy of the orbit and tear drainage.

The lacrimal gland is the primary tear producer. It lies in the lacrimal fossa in the superolateral aspect of the orbit and consists of orbital and palpebral portions. Tears spread across the ocular surface as the tear film, which comprises lipid, aqueous, and mucin layers. Parasympathetic secretomotor fibers from the facial nerve reach the lacrimal gland via the greater petrosal nerve and the nerve of the pterygoid canal.

Tear drainage involves the lacrimal drainage apparatus. Tears are collected at the medial eyelids by the lacrimal puncta, pass through the superior and inferior canaliculi into the lacrimal sac, and drain via the nasolacrimal duct into the inferior meatus of the nasal cavity. This drainage system helps regulate tear volume and ocular surface moisture.

Lacrimal bone refers to a small, fragile facial bone forming part of the medial wall of the orbit and the lacrimal fossa that houses the lacrimal sac. The bone contains the lacrimal groove and contributes to the nasolacrimal duct pathway. It articulates with the frontal bone, maxilla, ethmoid, and inferior nasal concha.

Clinical issues involving lacrimal structures include dry eye, epiphora (excessive tearing), nasolacrimal duct obstruction, dacryocystitis, and tear film disorders.