The lacrimal apparatus [2] ( lat. Apparatus lacrimalis ) [3] is a physiological system containing orbital structures for lacrimal production and drainage [4] . It is an auxiliary structure of the eyes . It is subdivided into organs of tear production and organs of lacrimation (drainage) [5] .
| Lacrimal apparatus | |
|---|---|
| lat Appliance lacrimalis | |
 Tearful apparatus. Right side. | |
| Catalogs | |
Content
Anatomy
Organs of tear production
The organs of tear production ( syn. Tear secretion, tear secretion ) include:
- lacrimal glands , the main and additional, producing the main part of the lacrimal fluid
- tear ducts of the lacrimal glands
Despite the fact that a number of exocrine glands , secretory and epithelial cells of the cornea , conjunctiva and eyelids are also involved in the formation of lacrimal fluid, they are not referred to in the medical literature as the lacrimal apparatus, but are considered together with the relevant organs, where they perform the main function. So, epithelial cells perform an integumentary function. Meibomian glands - secrete a secret that gives hydrophobicity to the edge of the eyelids, thereby preventing their wetting , constant leakage of tear fluid and maceration of the skin. Zeiss sebaceous glands provide fatty lubrication of the eyelashes , as a variety of hair .
Tear Organs
In a normal state, tear fluid is constantly being renewed in the eyes, which is achieved by its constant secretion and removal of accumulated excess from the conjunctival sac into the lower nasal passage of the nasal cavity . The anatomical structures involved in such removal of the lacrimal fluid are called tear ducts or organs . These include:
- tear stream
- tear lake
- tear meat
- lacrimal papillae with lacrimal openings
- lacrimal tubules
- tear bag
- nasolacrimal duct
Conventionally, it can be divided into external visible ( lacrimal stream, lacrimal opening, lacrimal meat, lacrimal papillae with lacrimal openings ) and internal ( lacrimal tubules, lacrimal sac, nasolacrimal duct ).
The tear stream ( lat. Rivus lacrimalis ) is not a structural permanent tissue formation, is formed functionally in the form of a small tubule between the beveled posterior edge of the lower eyelid and the front surface of the eyeball . When the eyelids close, including when blinking, it is a narrow gap or tube. It extends along the edge of the eyelids from the outer to the inner edge of the eyelids. Filled with tear fluid. When closing the eyelids, tear fluid is directed along it from the outer corner of the eye to the inner, to the tear lake.
The tear lake ( lat. Lacus lacrimalis ) is a small, cup-shaped, helical cavity between the mucous membranes of the conjunctiva of the sclera and the lower eyelid (with closed eyelids and between the upper eyelid) in the inner ( medial ) corner of the palpebral fissure, located around the lacrimal flesh. Filled with tear fluid.
The lacrimal meat ( Latin caruncula lacrimalis ) is a small elevation formed by the fold of the conjunctiva between the upper and lower eyelids in the inner corner of the palpebral fissure, medial to the lunate fold . Around the lower half (with open eyelids) of the tear meat there is a tear lake. On the tear meat in abundance are secreting mucin goblet cells of the Becher conjunctiva.
The lacrimal papillae ( lat. Papillae lacrimales ) are small cone-shaped elevations on the conjunctival mucosa at the edge of the eyelids in the medial part of them in the projection of the lateral edge of the lacrimal meat. In each eye, there is one upper and lower lacrimal papilla, respectively, on the upper and lower eyelids. At the tops of the lacrimal papillae there is one hole with a diameter of about 0.5 mm - lacrimal openings ( lat. Puncta lacrimalia ), through which the tear fluid from the lacrimal lake enters the lacrimal tubules. Normally, the tear points are constantly immersed in the tear fluid of the tear lake.
The lacrimal canaliculi ( lat.canaliculi lacrimales ) - small canaliculi extending vertically from the lacrimal openings about 1.5 mm, then bending horizontally in the medial direction and falling separately or uniting into one canal in the lacrimal sac. Distinguish, respectively, the lacrimal openings, the upper and lower lacrimal tubules. Each has a total length of about 0.6-1 cm, a diameter of about 0.5 mm. In the initial part, they have an extension - an ampule of the lacrimal tubule , at the confluence there is a Meyer sinus , folds of the mucosa form valves that prevent the reverse flow of the tear fluid: Guške’s valve (below) and Rosenmüller’s valve (above).
The lacrimal sac ( Latin saccus lacrimalis ) is a connective tissue hollow sac narrowed above and below, located behind the skin and the medial ligament of the eyelids in the lower medial corner of the orbit in the fossa of the lacrimal sac formed by the lacrimal groove of the frontal process of the upper jaw and the lacrimal gut of the lacrimal bone . The fibers of the secular and lacrimal parts of the circular muscle of the eye are woven into the walls of the lacrimal sac. Inside, the lacrimal sac is covered with a cylindrical and ciliated epithelium. From above, the mouths of the lacrimal tubules open into the lacrimal sac; from below, without a sharp distinction, it passes into the nasolacrimal duct. The lacrimal sac is about 1 cm long and about 3 mm wide.
The nasolacrimal duct ( lat. Ductus nasolacrimalis ) is a connective tissue tube located in the upper part in the nasolacrimal duct of the nasal surface of the upper jaw . It starts from the lacrimal sac in the opening formed by the lacrimal notch of the orbital surface of the frontal process of the upper jaw and the lacrimal hook of the lacrimal bone. The medially nasolacrimal canal with the nasolacrimal duct located in it is closed by the nasal mucosa. From below, the nasolacrimal canal opens with an opening in the mucous membrane of the anterior part of the lower nasal passage of the nasal cavity on the lateral wall 3-3.5 cm from the nostrils . At the hole in the nasal cavity, the fold of the duct mucosa forms the Gasner valve , as in the lacrimal tubules, it prevents the tear fluid from flowing back and the contents of the nasal cavity into the nasolacrimal duct. The length of the nasolacrimal duct is 1-2 cm, the diameter is about 4 mm. Inside, the nasolacrimal canal is covered with ciliated and cylindrical epithelium.
The innervation of the lacrimal apparatus is produced by the plexus of nerves of the internal and external sympathetic nervous system , only the salivary nuclei of the facial nerve are from the parasympathetic nervous system .
Physiology
Pathology
In case of defects in the valves of the tear ducts, when they do not impede the reverse flow of the tear fluid, a trick is possible when smoke is released from the inner corners of the eyes when smoking .
Inflammation of the lacrimal glands and are called dacryoadenitis and dacryocystitis, respectively.
Dacryolithiasis is the formation of dacryoliths (lacrimal stones).
See also
- Eustachian tube
Notes
- ↑ 1 2 Foundational Model of Anatomy
- ↑ Lacrimal apparatus // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- ↑ Sinelnikov R. D. , Sinelnikov Ya. R. , Sinelnikov A. Ya. Atlas of human anatomy. Study guide . / In 4 vol. T. 4, 7th ed. reslave. // M .: RIA Novaya wave / Publisher Umerenkov. - 2010 .-- 312 p., Ill. ISBN 978-5-7864-0202-6 / ISBN 978-5-94368-053-3 . (S. 252-256).
- ↑ Cassin, B. and Solomon, S. Dictionary of Eye Terminology . Gainesville, Florida: Triad Publishing Company, 1990.
- ↑ Avetisov S.E. , Egorov E.A. , Moshetova L.K. , Neroev V.V. , Takhchidi H.P. Ophthalmology: national leadership // M .: GEOTAR-Media . - 2008 .-- 944 p., Ill. ISBN 978-5-9704-0707-3 . (S. 72-83, 362-399).
Literature
- Diseases of the lacrimal organs: Monograph / B. F. Cherkunov - Samara: SE "Perspective", 2001. - 296 p. - ISBN 5-900031-43-8 .
- Eye diseases. Full reference book / Perederii V.A. - M .: Eksmo , 2008. - 704 p. - ISBN 978-5-699-25989-2 .
- Beloglazov V.G. Lacrimal organs // Big Medical Encyclopedia , 3rd ed. - M .: Soviet Encyclopedia. - T. 23.
- The lacrimal and nasal canal // Brockhaus and Efron Encyclopedic Dictionary : 86 t. (82 t. And 4 ext.). - SPb. , 1890-1907.
- The lacrimal apparatus, its diseases // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.