Traanklier

Traanklier refers to the lacrimal gland, a paired exocrine gland that produces the watery component of tears. In humans, there are two lacrimal glands, one in each orbit, located in the superolateral aspect of the eye within the lacrimal fossa. Each gland has orbital and palpebral lobes and works as part of the larger lacrimal apparatus that maintains the tear film.

The lacrimal gland secretes the aqueous component of tears, providing moisture, nutrients, and antimicrobial agents such as lysozyme. The tears are distributed across the ocular surface with blinking and then drain away through the lacrimal puncta at the medial canthus, into the canaliculi, the lacrimal sac, and finally the nasolacrimal duct into the nasal cavity. This drainage system helps regulate tear volume and eye moisture.

Secretion is primarily controlled by parasympathetic innervation from the facial nerve, via the greater petrosal nerve to the pterygopalatine ganglion. Postganglionic fibers travel with the zygomatic and lacrimal nerves to reach the gland. Sympathetic input modulates secretion but is less influential than the parasympathetic supply. The lacrimal gland is also involved in the reflex and emotional tear response, contributing to tear production in response to environmental stimuli and emotional states.

Clinical aspects include dacryoadenitis, an inflammation of the lacrimal gland that can be viral or bacterial. Chronic dry eye can result from autoimmune diseases such as Sjögren’s syndrome. Obstruction of tear drainage (nasolacrimal duct obstruction) can cause epiphora and recurrent infections. Tumors of the lacrimal gland are rare but documented. The term “traanklier” is commonly used in Dutch to denote this gland.