"Lacrimal gland In human physiology, the lacrimal glands are paired, almond-shaped exocrine glands, one for each eye, that secrete the aqueous layer of the tear film. They are situated in the upper lateral region of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called dacryoadenitis. The lacrimal gland produces tears which then flow into canals that connect to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose. Anatomists divide the gland into two sections. The smaller ""palpebral portion"" lies close to"
"Lacrimal artery The lacrimal artery is an artery that arises close to the optic foramen, and is one of the largest branches derived from the ophthalmic artery. Not infrequently it is given off before the artery enters the orbit. It accompanies the lacrimal nerve along the upper border of the lateral rectus and supplies the lacrimal gland. Its terminal branches, escaping from the gland, are distributed to the eyelids and conjunctiva: of those supplying the eyelids, two are of considerable size and are named the lateral palpebral arteries; they run medially in the upper and lower lids respectively and anastomose"
"Tears Tearing (), lacrimation, or lachrymation () is the secretion of tears, a body fluid which often serves to clean and lubricate the eyes in response to an irritation of the eyes. Tears formed through crying are associated with strong internal emotions, such as sorrow, elation, love, awe, and pleasure. Laughing or yawning may also lead to the production of tears. In humans, the tear film coating the eye, known as the precorneal film, has three distinct layers, from the most outer surface: Having a thin tear film may prevent one's ability to wear contact lenses, as the amount of"
"in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways. The lateral or orbital surface is divided by a vertical ridge, the posterior lacrimal crest, into two parts. In ""front"" of this crest is a longitudinal groove, the lacrimal sulcus (""sulcus lacrimalis""), the inner margin of which unites with the frontal process of the maxilla, and the lacrimal"
"the conjunctiva and cornea that together with lacrimal gland comprise much of the lacrimal functional unit (LFU). Viewed collectively, the LFU is the primary source of lacritin in the body, and the eye the main target. Dry eye is the most common eye disease, affecting 5 - 6% of the population. Prevalence rises to 6 - 9.8% in postmenopausal women, and as high as 34% in the elderly. Tears lubricate the lid and are important for the refraction of light. Tears also promote epithelial health. Only a small fraction of the estimated 1543 proteins in tears are differentially deficient or"
"Lacrimal bone The lacrimal bone is a small and fragile bone of the facial skeleton; it is roughly the size of the little fingernail. It is situated at the front part of the medial wall of the orbit. It has two surfaces and four borders. Several bony landmarks of the lacrimal bone function in the process of lacrimation or crying. Specifically, the lacrimal bone helps form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of the bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears or lacrimal fluid, from the lacrimal glands, collect"
"turn to the nasolacrimal duct, which dumps them out into the nose. Lacrimal glands are also present in other mammals, such as horses. The lacrimal gland is a compound tubuloacinar gland, it is made up of many lobules separated by connective tissue, each lobule contains many acini. The acini contain only serous cells and produce a watery serous secretion. Each acinus consists of a grape-like mass of ""lacrimal gland cells"" with their apices pointed to a central lumen. The central lumen of many of the units converge to form intralobular ducts, and then they unite to form interlobular ducts. The"
"the punctum is found. Lacrimal lake The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system (the ""puncta lacrimalia""). The volume of the lacrimal lake has been estimated to be between 7 and 10 µL. Although the lacrimal lake usually contains 7–10 µL of tears, the maximum fluid it can usually hold is 25–30 µL before tearing occurs. Aging usually causes the eyelids to become more loose which in turn enables the lacrimal lake to hold even more fluid. The lacrimal papilla is an elevation located on"
"middle meningeal artery. Lacrimal artery The lacrimal artery is an artery that arises close to the optic foramen, and is one of the largest branches derived from the ophthalmic artery. Not infrequently it is given off before the artery enters the orbit. It accompanies the lacrimal nerve along the upper border of the lateral rectus and supplies the lacrimal gland. Its terminal branches, escaping from the gland, are distributed to the eyelids and conjunctiva: of those supplying the eyelids, two are of considerable size and are named the lateral palpebral arteries; they run medially in the upper and lower lids"
"Lacrimal lake The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system (the ""puncta lacrimalia""). The volume of the lacrimal lake has been estimated to be between 7 and 10 µL. Although the lacrimal lake usually contains 7–10 µL of tears, the maximum fluid it can usually hold is 25–30 µL before tearing occurs. Aging usually causes the eyelids to become more loose which in turn enables the lacrimal lake to hold even more fluid. The lacrimal papilla is an elevation located on the medial canthus where"
"Nasolacrimal duct The nasolacrimal duct (also called the tear duct) carries tears from the lacrimal sac of the eye into the nasal cavity. The duct begins in the eye socket between the maxillary and lacrimal bones, from where it passes downwards and backwards. The opening of the nasolacrimal duct into the inferior nasal meatus of the nasal cavity is partially covered by a mucosal fold (valve of Hasner or ""plica lacrimalis""). Excess tears flow through nasolacrimal duct which drains into the inferior nasal meatus. This is the reason the nose starts to run when a person is crying or has"
"medial to the puncta lacrimalia; occasionally it is very indistinct. The lacrimal orbicularis facilitates the tear pump into the lacrimal sac. The muscle acts to close the eye, and is the only muscle capable of doing so. Loss of function for any reason results in an inability to close the eye, necessitating eye drops at the minimum to surgical closure of the eye in extreme cases. The palpebral portion acts involuntarily, closing the lids gently, as in sleep or in blinking; the orbital portion is subject to conscious control. When the entire muscle is brought into action, the skin of"
"Lacritin Lacritin is a 12.3 kDa glycoprotein encoded in humans by the LACRT gene. Lacritin's discovery emerged from a screen for factors that stimulate tear protein secretion. Lacritin is a secreted protein found in tears and saliva. Lacritin also promotes tear secretion, the proliferation and survival of epithelial cells, and corneal wound healing Lacritin is thus a multifunctional prosecretory mitogen with cell survival activity. Natural or bacterial cleavage of lacritin releases a C-terminal fragment that is bactericidal. Most lacritin is produced by the lacrimal gland, including the accessory lacrimal gland of Wolfring. Some lacritin is produced by the meibomian gland,"
"the lesser lacrimal bone. The medial or nasal surface presents a longitudinal furrow, corresponding to the crest on the lateral surface. The area in front of this furrow forms part of the middle meatus of the nose. The area behind it articulates with the ethmoid, and completes some of the anterior ethmoidal cells. Of the four borders: The lacrimal is ossified from a single center, which appears about the twelfth week in the membrane covering the cartilaginous nasal capsule. The lacrimal articulates with four bones: two of the cranium, the frontal and ethmoid, and two of the face, the maxilla"
"SDC1. Involvement of a G-protein coupled receptor would explain the rapidity of lacritin signaling. Lacritin is a glycoprotein of the human tear film, and to a lesser extent of saliva, lung lavage and plasma. It is mainly produced by the lacrimal gland. Some lacritin also is produced by the meibomian gland, and also by epithelial cells of the conjunctiva and cornea. The lacritin gene (""LACRT"") is one of the most transcriptionally regulated genes in the human eye. Functional studies suggest a role in epithelial renewal of some non-germative epithelia. By flowing downstream through ducts, it may generate a 'proliferative field'."
"tears that are made in response to irritants to the eye, such as when chopping onions or getting poked in the eye. Psychic tears are produced by the lacrimal system and are the tears expelled during emotional states. The lacrimal system is made up of a secretory system, which produces tears, and an excretory system, which drains the tears. The lacrimal gland is primarily responsible for producing emotional or reflexive tears. As tears are produced, some fluid evaporates between blinks, and some is drained through the lacrimal punctum. The tears that are drained through the punctum will eventually be drained"
"raphe at the outer canthus (corner) of eye. The palpebral portion contains the preseptal orbicularis and the pretarsal orbicularis muscles. The pretarsal orbicularis is thought to be responsible for the spontaneous blink The lacrimal part (tensor tarsi) is a small, thin muscle, about 6 mm in breadth and 12 mm in length, situated behind the medial palpebral ligament and lacrimal sac. It arises from the posterior crest and adjacent part of the orbital surface of the lacrimal bone, and passing behind the lacrimal sac, divides into two slips, upper and lower, which are inserted into the superior and inferior tarsi"
"palpebral conjunctival vessels will be supplied by both the ophthalmic artery and the external carotid artery, to varying extents. Sensory innervation of the conjunctiva is divided into four parts: The conjunctiva consists of non-keratinized, both stratified squamous and stratified columnar epithelium, with interspersed goblet cells. The epithelial layer contains blood vessels, fibrous tissue, and lymphatic channels. Accessory lacrimal glands in the conjunctiva constantly produce the aqueous portion of tears. Additional cells present in the conjunctival epithelium include melanocytes, T and B cell lymphocytes. The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears"
"Tear gas Tear gas, formally known as a lachrymator agent or lachrymator (from the Latin ""lacrima"", meaning ""tear""), sometimes colloquially known as mace, is a chemical weapon that causes severe eye and respiratory pain, skin irritation, bleeding, and even blindness. In the eye, it stimulates the nerves of the lacrimal gland to produce tears. Common lachrymators include pepper spray (OC gas), PAVA spray (nonivamide), CS gas, CR gas, CN gas (phenacyl chloride), bromoacetone, xylyl bromide, syn-propanethial-S-oxide (from onions), and Mace (a branded mixture). Lachrymatory agents are commonly used for riot control. Their use in warfare is prohibited by various international"
"Vaginal lubrication Vaginal lubrication is a naturally produced fluid that lubricates a woman's vagina. Vaginal lubrication is always present, but production increases significantly near ovulation and during sexual arousal in anticipation of sexual intercourse. Vaginal dryness is the condition in which this lubrication is insufficient, and sometimes artificial lubricants are used to augment it. Without sufficient lubrication, sexual intercourse can be painful. The vaginal lining has no glands, and therefore the vagina must rely on other methods of lubrication. Plasma from vaginal walls due to vascular engorgement is considered to be the chief lubrication source, and the Bartholin's glands, located"
"Lacrimal nerve The lacrimal nerve is the smallest of the three branches of the ophthalmic division of the trigeminal nerve. It sometimes receives a filament from the trochlear nerve that is derived from the branch that goes from the ophthalmic to the trochlear nerve. It passes forward in a separate tube of dura mater, and enters the orbit through the narrowest part of the superior orbital fissure. In the orbit it runs along the upper border of the lateral rectus, with the lacrimal artery, and communicates with the zygomatic nerve, a branch of the maxillary nerve. It enters the lacrimal"
"male gender, further workup is appropriate. Bloody punctual discharge or lacrimal sac distension above the medial canthal tendon is also highly suggestive of neoplasm. Congenital nasolacrimal duct obstruction, or dacryostenosis, occurs when the lacrimal duct has failed to open at the time of birth, most often due to an imperforate membrane at the valve of Hasner. Around 6% of infants have CLDO, usually experiencing a persistent watery eye even when not crying. If a secondary infection occurs (Dacryocystitis), purulent (yellow / green) discharge may be present. Most cases resolve spontaneously, with antibiotics reserved only if conjunctivitis occurs. Lacrimal sac massage"
"Posterior lacrimal crest The lateral or orbital surface of the lacrimal bone is divided by a vertical ridge, the posterior lacrimal crest, into two parts. In front of this crest is a longitudinal groove, the lacrimal sulcus (sulcus lacrimalis), the inner margin of which unites with the frontal process of the maxilla, and the lacrimal fossa is thus completed. The upper part of this fossa lodges the lacrimal sac, the lower part, the nasolacrimal duct. The portion behind the crest is smooth, and forms part of the medial wall of the orbit. The crest, with a part of the orbital"
"surface immediately behind it, gives origin to the lacrimal part of the orbicularis oculi and ends below in a small, hook-like projection, the lacrimal hamulus, which articulates with the lacrimal tubercle of the maxilla, and completes the upper orifice of the lacrimal canal; the hamulus sometimes exists as a separate piece, and is then called the lesser lacrimal bone. Posterior lacrimal crest The lateral or orbital surface of the lacrimal bone is divided by a vertical ridge, the posterior lacrimal crest, into two parts. In front of this crest is a longitudinal groove, the lacrimal sulcus (sulcus lacrimalis), the inner"
"Lymphatic system The lymphatic system is part of the vascular system and an important part of the immune system, comprising a large network of lymphatic vessels that carry a clear fluid called lymph (from Latin, ""lympha"" meaning ""water"") directionally towards the heart. The lymphatic system was first described in the seventeenth century independently by Olaus Rudbeck and Thomas Bartholin. Unlike the circulatory system, the lymphatic system is not a closed system. The human circulatory system processes an average of 20 litres of blood per day through capillary filtration, which removes plasma while leaving the blood cells. Roughly 17 litres of"
"contraction of the orbital to reduce glare while keeping the eyes open by virtue of the relaxation of the palpebral. Each time the eyelids are closed through the action of the orbicularis, the medial palpebral ligament is tightened, the wall of the lacrimal sac is thus drawn lateralward and forward, so that a vacuum is made in it and the tears are sucked along the lacrimal canals into it. The lacrimal part of the orbicularis oculi draws the eyelids and the ends of the lacrimal canals medialward and compresses them against the surface of the globe of the eye, thus"
"by capillary action, then flows through the lacrimal canaliculi at the inner corner of the eyelids entering the lacrimal sac, then on to the nasolacrimal duct, and finally into the nasal cavity. An excess of tears, as with strong emotion, can thus cause the nose to run. There are three very basic types of tears: The trigeminal V (fifth cranial) nerve bears the sensory pathway of the tear reflexes. When the trigeminal nerve is cut, tears from reflexes will stop, but not emotional tears.The lacrimal nerve from cranial nerve VII innervates the lacrimal gland, which is located within the orbit."
"Lacrimal canaliculi The lacrimal canaliculi, (sing. canaliculus), also known as the lacrimal canals or lacrimal ducts, are the small channels in each eyelid that commence at minute orifices, termed puncta lacrimalia, on the summits of the papillae lacrimales, seen on the margins of the lids at the lateral extremity of the lacus lacrimalis. At the angles they are dilated into ampullæ. Able to be seen under a microscope, they are lined by nonkeratinizing stratified squamous epithelium surrounded by fibrous tissue. Outside the latter is a layer of striped muscle, continuous with the lacrimal part of the orbicularis oculi; at the"
"than the lacrimal gland. It also contributes to immune surveillance and helps to prevent the entrance of microbes into the eye. Disorders of the conjunctiva and cornea are a common source of eye complaints, in particular because the surface of the eye is exposed to various external influences and is especially susceptible to trauma, infections, chemical irritation, allergic reactions and dryness. The bulbar conjunctival microvasculature contains arterioles, meta-arterioles, venules, capillaries, and communicating vessels. Vessel morphology varies greatly between subjects and even between regions of the individual eyes. In some subjects, arterioles and venules can be seen to run parallel with"
"branch passes through the orbit superiorly, then reenters the frontal bone briefly before exiting above the orbit through the superior orbital fissure and the supraorbital notch to provide sensory innervation for the skin of the forehead and scalp. The lacrimal nerve passes through the orbit superiorly to innervate the lacrimal gland. The nasociliary branch gives off several sensory branches to the orbit and then continues out through the anterior ethmoidal foramen, where it enters the nasal cavity and provides innervation for much of the anterior nasal mucosa. It also gives off a branch which exits through the nasal bones to"
"Blood is supplied to the cervix by the descending branch of the uterine artery and drains into the uterine vein. The pelvic splanchnic nerves, emerging as S2–S3, transmit the sensation of pain from the cervix to the brain. These nerves travel along the uterosacral ligaments, which pass from the uterus to the anterior sacrum. Three channels facilitate lymphatic drainage from the cervix. The anterior and lateral cervix drains to nodes along the uterine arteries, travelling along the cardinal ligaments at the base of the broad ligament to the external iliac lymph nodes and ultimately the paraaortic lymph nodes. The posterior"
"which efferent fibers from the superior salivary nucleus become improperly connected to nerve axons projecting to the lacrimal glands, causing one to shed tears (lacrimate) during salivation while smelling foods or eating. It is presumed that one would also salivate while crying due to the inverse improper connection of the lacrimal nucleus to the salivary glands, but this would be less noticeable. Keratoconjunctivitis sicca, known as dry eye, is a very common disorder of the tear film. However, sufferers can experience watering of the eyes, which is in fact a response to irritation caused by the original tear film deficiency."
"glands are in the areola that surrounds the nipple in the female breast. These glands secrete an oily fluid that lubricates the nipple, and also secrete volatile compounds that are thought to serve as an olfactory stimulus for the newborn. During pregnancy and lactation these glands, also called Montgomery's glands, become enlarged. Meibomian glands, in the eyelids, secrete a form of sebum called meibum onto the eye, that slows the evaporation of tears. It also serves to create an airtight seal when the eyes are closed and its lipid quality also prevents the eyelids from sticking together. The meibomian glands"