Tear fold

The lacrimal fold (plica lacrimalis) is an anatomical structure that is located on the inner surface of the lower eyelid. It plays an important role in the process of outflow of tears from the eyeball.

The lacrimal fold consists of two layers: superficial and deep. The surface layer consists of a mucous membrane and contains a large number of small glands that secrete secretions. The deep layer consists of connective tissue that forms folds and provides elasticity to the fold.

One of the functions of the tear fold is to drain tears from the eye. When the eyeball moves, the tear fluid enters the lacrimal fold, then it flows down the tear ducts into the nasal cavity. Thanks to this process, the eyes remain moist and vision does not deteriorate.

In addition, the lacrimal fold is involved in the formation of the eyelids. It is part of the lower eyelid and helps it close and open. When the eye closes, the lacrimal gland secretes a large amount of secretion, which moisturizes the mucous membrane of the eye and protects it from drying out.

However, with some diseases, the tear fold may become damaged or inflamed. This can lead to various health problems such as watery eyes, red eyes, dry eyes, etc. In such cases, it is necessary to consult a doctor for diagnosis and treatment.

**Introduction**

The lacrimal fold is an important anatomical formation that plays a key role in the normal functioning of the lacrimal apparatus, ensuring the outflow of tears from the nose and eye through the lacrimal canal into the nasopharynx. Dysfunction of the tear fold can lead to various eye diseases, such as entropion of the eyelids, lacrimation, various forms of conjunctivitis, etc.

**Anatomy of the lacrimal membrane**

The facial surface of the eyelid is covered by the lacrimal gland, glandular tissue that forms the hairs of the nasolacrimal duct. This canal runs along the facial surface of the eyelid, parallel to the edge of the palpebral fissure. Its function is to drain secretion from the lacrimal gland of the mucous membrane of the eye through the angle and excretory canals into the lacrimal sac and further into the nasal cavity. Under its own epithelium and coarse connective tissue fibers, the membrane forms a thin, fairly elastic “tear fold” that separates the lacrimal sac from the rectus muscle of the eye. The fibrous fabric here has a horizontal direction, which gives the fold the shape of a glass, or an arc. From the inner corner of the eye downward, into the rectus muscle of the eyelid, it penetrates under its outer epithelial surface in the form of a thin but rather dense cord-like cord that bends under the epithelium, superficially covering the free edge of the lacrimal gland.

When retracted, the lacrimal gland forms a spherical capical fossa - a depression in the limbal region, located slightly anterior and lateral to the anterior edge of the lacrimal puncta. The lacrimal sac, ending at a wide base, penetrates between the levator tendon of the upper eyelid and the interaxial plate of cartilage into the conjunctiva of the eyeball. It opens medial to the lacrimal openings with two openings - the upper (at the thinned limbus) and the lower (located at the lower lacrimal punctum).

After beating in drops, the lacrimal fluid enters the lacrimal protrusion of the medial angle, from where it penetrates into the tear along the lacrimal ducts, in general embryogenesis which is caused by pathetic movements upward to the cornea.

Next, the lacrimal vein actively moves down and out along the surface of the conjunctiva, as well as along the lower vault of the nasal cavity, washing the outer layer of the facial nerve, which forms the upper posterior wall of the pharyngeal ampulla, where it mixes with the accumulated mucus from the external nasal passages and penetrates into the paranasal sinuses, where distributed through a well-developed system of venous capillaries in this area.

Next, the liquid waste enters small lacrimal glands (about six of them), located above the root of the upper jaw on the upper surface of the pyramids of the temporal bone, from where, through separate ducts, they again reach the lacrimal glands that secrete saliva.