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Nasolacrimal duct

 

 
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Nasolacrimal duct
 
 
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The nasolacrimal duct (sometimes called tear duct) carries tears
Tears

Tears are the liquid product of a process of lacrimation to clean and lubricate the eyes. The word lacrimation may also be used in a medical or literary sense to refer to crying....
 from the lacrimal sac
Lacrimal sac

The lacrimal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla....
 into the nasal cavity
Nasal cavity

The nasal cavity is a large air-filled space above and behind the nose in the middle of the face....
. Excess tears flow through nasolacrimal duct which opens in the nose
Nose

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for Respiration in conjunction with the mouth....
. This is the reason the nose starts to run when a person is crying or has watery eyes from an allergy, and why one can sometimes taste eye drops.

Like the lacrimal sac, the duct is lined by stratified columnar epithelium containing mucus-secreting goblet cells, and is surrounded by connective tissue.

Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora
Epiphora (medical)

Epiphora is overflow of tears onto the face. A clinical sign or condition that constitutes insufficient tears drainage from the eyes in that tears will drain down the face rather than through the nasolacrimal system....
.






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The nasolacrimal duct (sometimes called tear duct) carries tears
Tears

Tears are the liquid product of a process of lacrimation to clean and lubricate the eyes. The word lacrimation may also be used in a medical or literary sense to refer to crying....
 from the lacrimal sac
Lacrimal sac

The lacrimal sac is the upper dilated end of the nasolacrimal duct, and is lodged in a deep groove formed by the lacrimal bone and frontal process of the maxilla....
 into the nasal cavity
Nasal cavity

The nasal cavity is a large air-filled space above and behind the nose in the middle of the face....
. Excess tears flow through nasolacrimal duct which opens in the nose
Nose

Anatomically, a nose is a protuberance in vertebrates that houses the nostrils, or nares, which admit and expel air for Respiration in conjunction with the mouth....
. This is the reason the nose starts to run when a person is crying or has watery eyes from an allergy, and why one can sometimes taste eye drops.

Like the lacrimal sac, the duct is lined by stratified columnar epithelium containing mucus-secreting goblet cells, and is surrounded by connective tissue.

Obstruction of the nasolacrimal duct leads to the excess overflow of tears called epiphora
Epiphora (medical)

Epiphora is overflow of tears onto the face. A clinical sign or condition that constitutes insufficient tears drainage from the eyes in that tears will drain down the face rather than through the nasolacrimal system....
. Persons with dry eye conditions can be fitted with punctal plugs that seal the ducts to limit the amount of fluid drainage and retain moisture.

The canal containing the nasolacrimal duct is called the nasolacrimal canal
Nasolacrimal canal

The canal containing the nasolacrimal duct is called the nasolacrimal canal.It is formed by indentations in the inferior nasal conchae, maxilla and lacrimal bone....
.

Additional images


See also

  • Congenital lacrimal duct obstruction
    Congenital lacrimal duct obstruction

    Congenital nasolacrimal duct obstruction is literally a lacrimal duct that has failed to open at the time of birth. Around 6% of infants have CLDO, usually experiencing a persistent watery eye even when not crying....
  • Orbit (anatomy)
    Orbit (anatomy)

    In anatomy, the orbital bone is the cavity or socket of the skull in which the eye and its adnexa are situated.It can also mean the skin which surrounds the eye of a bird....
  • Lacrimal apparatus
    Lacrimal apparatus

    The lacrimal apparatus is the physiologic system containing the orbital structures for tear production and drainage.It consists of:* the lacrimal gland, which secretes the tears, and its excretory ducts, which convey the fluid to the surface of the eye;...


External links


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