question: Why when we yawn our eyes are starting to water?
comment: Certain facial muscles tense when you yawn, pushing out the water out of the gland where tears are produced.
passages: found also with "-n-" suffix in Greek χαίνω "to yawn", and without the "-n-" in English "gap" (compare the "figura etymologica" in Norse "ginnunga-gap"), "gum" "palate" and "gasp" (via Old Norse), Latin "hiō, hiatus", and Greek "chasm, chaos".
  
  The Latin term used in medicine is "oscitatio" (anglicized as "oscitation"), from the verb "oscito" "to open the mouth". 
  
  "Pandiculation" is the act of yawning and stretching simultaneously.
  
  Section::::Proposed causes.
   Lacrimal apparatus
  
  The lacrimal apparatus is the physiological system containing the orbital structures for tear production and drainage. It consists of:
  
  BULLET::::- The lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the human eye;it is a serous gland located in lacrimal fossae.it is a j shaped gland
  
  BULLET::::- The lacrimal canaliculi, the lacrimal sac, and the nasolacrimal duct, by which the fluid is conveyed into the cavity of the nose, emptying anterioinferiorly to the inferior nasal conchae from the nasolacrimal duct;
   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 placing them in the most favorable situation for receiving the tears; it also compresses the lacrimal sac. This part comprises two pieces: Horner's muscle and the muscle of Riolan, the latter helps hold the eyelids together to keep the lacrimal passage waterproof.
   Another notion states that yawning is the body's way of controlling brain temperature. In 2007, researchers, including a professor of psychology from the University of Albany, proposed yawning may be a means to keep the brain cool. Mammalian brains operate best within a narrow temperature range. In two experiments, subjects with cold packs attached to their foreheads and subjects asked to breathe strictly-nasally exhibited reduced contagious-yawning when watching videos of people yawning. 
   Water in the eye can alter the optical properties of the eye and blur vision. It can also wash away the tear fluid—along with it the protective lipid layer—and can alter corneal physiology, due to osmotic differences between tear fluid and freshwater. Osmotic effects are made apparent when swimming in freshwater pools, because the osmotic gradient draws water from the pool into the corneal tissue (the pool water is hypotonic), causing edema, and subsequently leaving the swimmer with "cloudy" or "misty" vision for a short period thereafter. The edema can be reversed by irrigating the eye with hypertonic saline which osmotically draws the excess water out of the eye.
   Drooling or sialorrhea can occur during sleep. It is often the result of open-mouth posture from CNS depressants intake or sleeping on one's side. Sometimes while sleeping, saliva does not build up at the back of the throat and does not trigger the normal swallow reflex, leading to the condition. Freud conjectured that drooling occurs during deep sleep, and within the first few hours of falling asleep, since those who are affected by the symptom suffer the most severe harm while napping, rather than during overnight sleep.
   A similar hypothesis suggests yawning is used for regulation of body temperature. Similarly, Guttmann and Dopart (2011) found, that, when a subject wearing earplugs yawned, a breeze is heard, caused by the flux of the air moving between the subject's ear and the environment. Guttmann and Dopart determined that a yawn causes one of three possible situations to occur: the brain cools down due to an influx or outflux of oxygen, the pressure in the brain is reduced by an outflux of oxygen, or the pressure of the brain is increased by an influx of air caused by increased cranial space.
   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.
   BULLET::::- learn to wake with eyes closed and still and keeping artificial tear drops within reach so that they may be squirted under the inner corner of the eyelids if the eyes feel uncomfortable upon waking.
   Epiphora, or watering eyes, is a condition in which tears flow out of the eyes, bypassing the lacrimal puncta. It is primarily caused by excessive tear production (as a result of emotion, irritation or dryness) or blockage of the drainage system. Such a blockage is a common problem among elderly people, as the tear ducts can narrow or get blocked easily. The same condition is also present in newborn babies, as their tear ducts don’t open until some time after birth.
  
  Section::::See also.
  
  BULLET::::- Punctal plug
  
  Section::::External links.
  
  BULLET::::- Punctoplasty - to correct watering eyes
   One study states that yawning occurs when one's blood contains increased amounts of carbon dioxide and therefore becomes in need of the influx of oxygen (or expulsion of carbon dioxide) that a yawn can provide. Yawning may, in fact, reduce oxygen intake compared to normal respiration. However, neither providing more oxygen nor reducing carbon dioxide in air decreased yawning.
   Punctoplasty
  
  Punctoplasty is a surgical procedure to restore proper drainage of tears when the lacrimal punctum (puncta lacrimalia) becomes blocked in one or both eyes.
  
  If a blockage is present in the puncti, doctors may suggest a procedure called punctoplasty, performed to widen the drain opening. This usually takes 20–30 minutes and is performed under local anesthesia.
  
  Section::::Rationale.
   Lacrimal punctum
  
  The lacrimal punctum (plural "puncta") or lacrimal point, is a minute opening on the summits of the lacrimal papillae, seen on the margins of the eyelids at the lateral extremity of the lacrimal lake. There are two lacrimal puncta in the medial (inside) portion of each eyelid.
  
  Together, they function to collect tears produced by the lacrimal glands. The fluid is conveyed through the lacrimal canaliculi to the lacrimal sac, and thence via the nasolacrimal duct to the inferior nasal meatus of the nasal passage.
  
  Section::::See also.
  
  BULLET::::- Imperforate lacrimal punctum
  
  BULLET::::- Lacrimal apparatus
  
  BULLET::::- Punctal plug
   Excessive moisture as tears collected in the lacrimal sac travel down the nasolacrimal ducts where they drain into the inferior meatus in the nasal cavity.
  
  Section::::Structure.:Nose shape.
  
  The shape of the nose varies widely due to differences in the nasal bone shapes and formation of the bridge of the nose. Some nose shapes were classified for surgeries by Eden Warwick in "Nasology" 1848:
   Section::::Causes.
  
  Any abnormality of any one of the three layers of tears produces an unstable tear film, resulting in symptoms of dry eyes.
  
  Section::::Causes.:Decreased tear or excessive evaporation.
   Close your eyes and press the Cuanzhu acupoint which is located at inner end of the brows with the other fingers relaxed and placed on the forehead. Massage the area once per beat and do this 32 times in total rhymically.
  
  Section::::Content.:The second session.
  
  Put both of your index fingers on the Jingming acupoint which refers to the area between the inner eye corners and the nose, with other fingers making a fist. Massage the acupoint up and down once per beat, and do it 32 times.
  
  Section::::Content.:The third session.
   BULLET::::- SET: "for we have heard how HASHEM dried up the waters of the Sea of Reeds for you when you went forth from Egypt and what you did to the two kings of the Amorites who were across the Jordan - to Sihon and to Og - whom you utterly destroyed."
  
  Joshua’s speech to the troops shortly before the conquest of Jericho:
   Section::::1948 flood.
   There may also be a stringy discharge from the eyes. Although it may seem strange, dry eye can cause the eyes to water. This can happen because the eyes are irritated. One may experience excessive tearing in the same way as one would if something got into the eye. These reflex tears will not necessarily make the eyes feel better. This is because they are the watery type that are produced in response to injury, irritation, or emotion. They do not have the lubricating qualities necessary to prevent dry eye.
   There are a number of theories that attempt to explain why humans and other animals yawn. It is likely that there are a number of triggers for the behavior. However, there are comparatively few theories that attempt to explain the primary evolutionary reason for the yawn.
   The iris contains two groups of smooth muscles; a circular group called the sphincter pupillae, and a radial group called the dilator pupillae. When the sphincter pupillae contract, the iris decreases or constricts the size of the pupil. The dilator pupillae, innervated by sympathetic nerves from the superior cervical ganglion, cause the pupil to dilate when they contract. These muscles are sometimes referred to as intrinsic eye muscles.
   The entrance to Zedekiah's Cave is just beneath the Old City wall, between the Damascus and Herod Gates, about east of the former. Beyond the narrow entrance, the cave slopes down into a vast 300-foot-long auditorium-like chamber. Drops of water, known as “Zedekiah's tears”, trickle through the ceiling.
   During a yawn, the tensor tympani muscle in the middle ear contracts, creating a rumbling noise from within the head. Yawning is sometimes accompanied, in humans and other animals, by an instinctive act of stretching several parts of the body, including arms, neck, shoulders and back.
  
  Section::::Etymology.
  
  English "yawn" continues a number of Middle English forms, 
  
  "yanen" from Old English "ġānian", and "yenen, yonen" from Old English frequentatives "ġinian, ġionian", from a Germanic root "*gīn-". The Germanic root has Indo-European cognates, from a root "*g̑hēi-"
   Entropion, found in about 3% of the breed, is the rolling in of the eyelids, which causes the eyelashes to irritate the eye. Entropion is a condition that often requires surgery to fix, but once corrected causes no future issues for the dog.
  
  Section::::Health.:Lick fit.
   In the built environment, evaporation limited capillary penetration is responsible for the phenomenon of rising damp in concrete and masonry, while in industry and diagnostic medicine this phenomenon is increasingly being harnessed in the field of paper-based microfluidics.
  
  In physiology, capillary action is essential for the drainage of continuously produced tear fluid from the eye. Two canaliculi of tiny diameter are present in the inner corner of the eyelid, also called the lacrimal ducts; their openings can be seen with the naked eye within the lacrymal sacs when the eyelids are everted.
  