The parotid duct or Stensen duct is a salivary duct. It is the route that

saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...

takes from the major

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

, the

parotid gland The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the m ...

, into the

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

Structure

The parotid duct is formed when several interlobular ducts, the largest ducts inside the

, join. It emerges from the parotid gland. It runs forward along the

lateral Lateral is a geometric term of location which may also refer to: Biology and healthcare * Lateral (anatomy), a term of location meaning "towards the side" * Lateral cricoarytenoid muscle, an intrinsic muscle of the larynx * Lateral release ( ...

side of the

masseter muscle In anatomy, the masseter is one of the muscles of mastication. Found only in mammals, it is particularly powerful in herbivores to facilitate chewing of plant matter. The most obvious muscle of mastication is the masseter muscle, since it is the ...

for around 7 cm. In this course, the duct is surrounded by the buccal fat pad. It takes a steep turn at the border of the masseter muscle and passes through the

buccinator muscle The bucinator () is a thin quadrilateral muscle occupying the interval between the maxilla and the Human mandible, mandible at the side of the face. It forms the anterior part of the cheek or the lateral wall of the oral cavity.Illustrated Anatom ...

, opening into the vestibule of the mouth, the region of the mouth between the

cheek The cheeks () constitute the area of the face below the eyes and between the nose and the left or right ear. ''Buccal'' means relating to the cheek. In humans, the region is innervated by the buccal nerve. The area between the inside of th ...

and the gums, at the parotid papilla, which lies opposite to the second maxillary (upper)

molar tooth The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone toot ...

. The parotid papillae can be palpated as small raised tissue area ( papillae) on both sides of the mouth and protects the opening of the parotid duct. The buccinator acts as a valve that prevents air forcing into the duct, which would cause pneumoparotitis.

Relations

The parotid duct lies close to the buccal branch of the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of ta ...

(VII). It is also close to the transverse facial artery. Running along with the duct superiorly is the transverse facial artery, and the upper

buccal nerve The buccal nerve (long buccal nerve) is a sensory nerve of the face arising from the mandibular nerve (CN V3) (which is itself a branch of the trigeminal nerve). It conveys sensory information from the skin of the cheek, and parts of the oral mu ...

. The lower buccal nerve runs inferiorly along the duct.

Clinical significance

Blockage, whether caused by salivary duct stones or external compression, may cause pain and swelling of the

(

parotitis Parotitis is an inflammation of one or both parotid glands, the major salivary glands located on either side of the face, in humans. The parotid gland is the salivary gland most commonly affected by inflammation. Etymology From Greek παρωτῖ ...

). Koplik's spots which are pathognomonic of

measles Measles (probably from Middle Dutch or Middle High German ''masel(e)'', meaning "blemish, blood blister") is a highly contagious, Vaccine-preventable diseases, vaccine-preventable infectious disease caused by Measles morbillivirus, measles v ...

are found near the opening of the parotid duct. The parotid duct may be cannulated by inserting a tube through the internal orifice in the

. Dye may be injected to allow for imaging of the parotid duct.

History

Niels Stensen (also known as Nicolas Steno), a Danish

anatomist Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

(albeit best known as a

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

) is credited with the first detailed description of the duct in 1660, hence the origin of its alternative name "Stensen duct".

Additional images

File:Gray1200.png, Outline of side of face, showing chief surface markings. File:Parotid-interlobular duct.JPG, Microscopic slide of a human interlobular duct. File:Parotid-striated duct.JPG, Microscopic slide of a human striated duct. File:Parotid duct papillae.JPG, The left papilla (soft tissue protuberance at the exit) of the parotid duct is clearly visible on the cheek in the right of the photo. File:Slide6rrrr.JPG, Parotid duct File:Slide7yyyy.JPG, Parotid duct File:Slide3BBB.JPG, Parotid duct

References

External links

Diagram at MSU
* - Parotid duct injuries * {{Authority control Glands of mouth Saliva