The paired submandibular glands (historically known as submaxillary glands) are 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 ...

s located beneath the

floor of the mouth In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth. In addition to its primary role as the beginning ...

. In adult humans, they each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimulation their contribution decreases in proportion as

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 ...

secretion rises to 50%. The average length of the normal adult human submandibular salivary gland is approximately 27 mm, while the average width is approximately 14.3 mm.

Structure

Each submandibular gland is divided into a superficial lobe and a deep lobe, the two being separated by the

mylohyoid muscle The mylohyoid muscle or diaphragma oris is a paired muscle of the neck. It runs from the Human mandible, mandible to the hyoid bone, forming the floor of the oral cavity of the human mouth, mouth. It is named after its two attachments near the mo ...

: * The superficial lobe comprises most of the gland, with the mylohyoid muscle runs under it * The deep lobe is the smaller part

Submandibular duct

Secretions are delivered into the

submandibular duct The submandibular duct (also Wharton's duct or historically submaxillary duct) is one of the salivary excretory ducts. It is about 5 cm long, and its wall is much thinner than that of the parotid duct. It drains saliva from each bilateral submand ...

on the deep portion after which they hook around the posterior edge of the mylohyoid muscle and proceed on the superior surface laterally. The excretory ducts are then crossed by the

lingual nerve The lingual nerve carries sensory innervation from the anterior two-thirds of the tongue. It contains fibres from both the mandibular division of the trigeminal nerve (CN V) and from the facial nerve (CN VII). The fibres from the trigeminal nerve ...

, and ultimately drain into the sublingual caruncles , which are small prominences on either side of the

lingual frenulum The frenulum (or frenum) of the tongue, tongue web, lingual frenulum, frenulum linguae, or fraenulum is a small fold of mucous membrane extending from the floor of the mouth to the midline of the underside of the human tongue. Development The ton ...

along with the major sublingual duct. The gland can be bilaterally

palpated Palpation is the process of using one's hands to check the body, especially while perceiving/diagnosing a disease or illness. Usually performed by a health care practitioner, it is the process of feeling an object in or on the body to determine ...

(felt) inferior and posterior to the body of the mandible, moving inward from the inferior border of the mandible near its angle with the head tilted forwards.

Submandibular gland papilla

The terminal part of the submandibular (Wharton) duct is located in the mouth floor and opens as an orifice of the submandibular duct papilla. The position of the duct and its 0.5–1.5 mm wide ostium is invariably symmetric, but quite unpredictable; consequently, submandibular duct papillae can occasionally be challenging to recognize. Based on the macroscopic appearance of the papillae and a

sialoendoscopic Sialoendoscopy is a Minimally invasive procedure, minimally invasive technique that allows for salivary gland surgery for the safe and effective treatment of sialadenitis, obstructive salivary gland disorders and other conditions of the salivary gl ...

approach, Anicin et al. described four different types of submandibular gland papillae: types A, B, C, and D.

Microanatomy

Lobes contain smaller lobules, which contain adenomeres, the secretory units of the gland. Each adenomere contains one or more

acini An acinus (; : acini; adjective, acinar or acinous) refers to any cluster of cells that resembles a many-lobed "berry", such as a raspberry (''acinus'' is Latin for "berry"). The berry-shaped termination of an exocrine gland, where the secret ...

, or alveoli, which are small clusters of cells that secrete their products into a duct. The acini of each adenomere are composed of either

serous In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fl ...

mucous cell Mucous glands, also known as muciparous glands, are found in several different parts of the body, and they typically stain lighter than serous glands during standard histological preparation. Most are multicellular, but goblet cells are single-ce ...

s, with serous adenomeres predominating. Some mucous adenomeres may also be capped with a

serous demilune Serous demilunes, also known as Crescents of Giannuzzi or Demilunes of Heidenhain, are cellular formations in the shape of a half-moon (hence the name "demilune") on the mixed submandibular and sublingual salivary glands. Serous demilunes are the ...

, a layer of

lysozyme Lysozyme (, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside hydrolase ...

-secreting serous cells resembling a half moon. Like other

exocrine gland Exocrine glands are glands that secrete substances onto an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate and mucous. Exocrine glands are one of ...

s, the submandibular gland can be classified by the microscopic anatomy of its secretory cells and how they are arranged. Because the glands are branched, and because the tubules forming the branches contain secretory cells, submandibular glands are classified as

branched tubuloacinar gland A branch is a part of a woody plant. Branch or branches may also refer to: Places Australia * The Branch River, New South Wales Canada * Branch, Newfoundland and Labrador, a town France * Branches, Yonne, a commune New Zealand * Branch Riv ...

s. Further, because the secretory cells are of both serous and mucous types, the submandibular gland is a mixed gland, and though most of the cells are serous, the exudate is chiefly mucous. It has long striated ducts and short intercalated ducts.Illustrated Dental Embryology, Histology, and Anatomy, Fehrenbach and Popowics, Elsevier, 2026, page 153 The secretory acinar cells of the submandibular gland have distinct functions. The mucous cells are the most active and therefore the major product of the submandibular glands is saliva which is mucoid in nature. Mucous cells secrete mucin which aids in the lubrication of the food bolus as it travels through the esophagus. In addition, the serous cells produce salivary amylase, which aids in the breakdown of starches in the mouth. The submandibular gland's highly active acini account for most of the salivary volume. The parotid and sublingual glands account for the remaining.

Blood supply

The gland receives its blood supply from the facial and lingual arteries. The gland is supplied by sublingual and submental arteries and drained by common facial and lingual veins.

Lymphatic drainage

The lymphatics from submandibular gland first drain into submandibular lymph nodes and subsequently into jugulo - digastric lymph nodes.

Nerve supply

Their secretions, like the secretions of other salivary glands, are regulated ''directly'' by the

parasympathetic nervous system The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ...

and ''indirectly'' by the

sympathetic nervous system The sympathetic nervous system (SNS or SANS, sympathetic autonomic nervous system, to differentiate it from the somatic nervous system) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous sy ...

. * ''Parasympathetic'' innervation to the submandibular glands is provided by the

superior salivatory nucleus The salivatory nuclei are two general visceral efferent fiber, general visceral efferent Nucleus (anatomy), nuclei located in the caudal pons, dorsal and lateral to the facial nucleus. Their neurons give rise to preganglionic nerve fibers, pregan ...

via the

chorda tympani Chorda tympani is a branch of the facial nerve that carries gustatory (taste) sensory innervation from the front of the tongue and parasympathetic ( secretomotor) innervation to the submandibular and sublingual salivary glands. Chorda tymp ...

, a 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 ...

, that becomes part of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

's lingual nerve prior to synapsing on the

submandibular ganglion The submandibular ganglion (or submaxillary ganglion in older texts) is part of the human autonomic nervous system. It is one of four parasympathetic ganglia of the head and neck. (The others are the otic ganglion, pterygopalatine ganglion, an ...

. Increased parasympathetic activity promotes the secretion of saliva. * The sympathetic nervous system regulates submandibular secretions through

vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vesse ...

of the arteries that supply it. Increased sympathetic activity reduces glandular bloodflow, thereby decreasing the volume of fluid in salivary secretions, producing an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

rich

mucous Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

saliva. Nevertheless, direct stimulation of sympathetic nerves will cause an increase in salivary enzymatic secretions. In sum, the volume decreases, but the secretions are increased by parasympathetic and sympathetic innervation.

Relations

The submandibular gland occurs within the

submandibular triangle The submandibular triangle (or submaxillary or digastric triangle) corresponds to the region of the neck immediately beneath the body of the mandible. Boundaries and coverings It is bounded: * ''above'', by the lower border of the body of the man ...

. It is situated posteroinferior to the

ramus of mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

, and between the two bellies of the

digastric muscle The digastric muscle (also digastricus) (named ''digastric'' as it has two 'bellies') is a bilaterally paired suprahyoid muscle located under the jaw. Its posterior belly is attached to the mastoid notch of temporal bone, and its anterior belly ...

Development

The submandibular salivary glands develop later than the parotid glands and appear late in the sixth week of prenatal development. They develop bilaterally from epithelial buds in the sulcus surrounding the sublingual folds on the floor of the primitive mouth. Solid cords branch from the buds and grow posteriorly, lateral to the developing tongue. The cords of the submandibular gland later branch further and then become canalized to form the ductal part. The submandibular gland acini develop from the cords’ rounded terminal ends at 12 weeks, and secretory activity via the submandibular duct begins at 16 weeks. Growth of the submandibular gland continues after birth with the formation of more acini. Lateral to both sides of the tongue, a linear groove develops and closes over to form the submandibular duct.

Function

The submandibular gland is one of the major three glands that provide the mouth with

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 ...

. The two other types of

salivary 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 minor s ...

glands are

parotid 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 ...

and

sublingual Sublingual (List of abbreviations used in medical prescriptions, abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through Tissue (biology), t ...

glands. The submandibular gland releases a host of factors which regulate systemic inflammatory responses and modulate systemic immune and inflammatory reactions. Early work in identifying factors that played a role in the cervical sympathetic trunk-submandibular gland (CST-SMG) axis lead to the discovery of a seven

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although over 500 amino acids exist in nature, by far the most important are the 22 α-amino acids incorporated into proteins. Only these 22 a ...

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

, called the submandibular gland peptide-T. SGP-T was demonstrated to have biological activity and thermoregulatory properties related to

endotoxin Lipopolysaccharide (LPS), now more commonly known as endotoxin, is a collective term for components of the outermost membrane of the cell envelope of gram-negative bacteria, such as '' E. coli'' and ''Salmonella'' with a common structural archit ...

exposure. SGP-T, an isolate of the submandibular gland, demonstrated its immunoregulatory properties and potential role in modulating the CST-SMG axis, and subsequently was shown to play an important role in the control of inflammation.

Clinical significance

Relative incidence of submandibular tumors

The submandibular gland accounts for 80% of all

salivary duct calculi Sialolithiasis (also termed salivary calculi, or salivary stones) is a crystallopathy where a calcified mass or ''sialolith'' forms within a salivary gland, usually in the duct of the submandibular gland (also termed "Wharton's duct"). Less common ...

(salivary stones or sialolith), possibly due to the different nature of the saliva that it produces and the tortuous travel of the submandibular duct to its ductal opening for a considerable upward distance.Illustrated Dental Embryology, Histology, and Anatomy, Fehrenbach and Popowics, Elsevier, 2026, page 156 Benign and malignant tumors can also develop in the submandibular gland (see pie chart).

Additional images

File:Gray177.png, Mandible. Inner surface. Side view. File:Gray778.png, Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion. File:WVSOM Submandibular Gland.JPG, Mucous cells are identifiable by the lack of color in their cytoplasm, while serosal cells have a basophilic color. File:SubmandInflaMark.png, Submandibular gland inflammation as seen on ultrasound

Dissection images

File:Submandibular gland.jpg, Submandibular gland File:Slide2a.JPG, Submandibular gland File:Slide1b.JPG, Submandibular gland lateral view File:Slide1c.JPG, Submandibular gland File:Slide1d.JPG, Submandibular gland - right view File:Slide1e.JPG, Submandibular gland - frontal view File:Slide5g.JPG, Submandibular gland File:Slide1EBA.JPG, Muscles, arteries and nerves of neck.Newborn dissection. File:Slide1EBAB.JPG, Muscles, arteries and nerves of neck.Newborn dissection. File:Slide2deded.JPG, Muscles, nerves and arteries of neck.Deep dissection. Anterior view. File:Anterior region of neck1.JPG, Submandibular gland

References

External links

Histology at usc.edu
* - "Anterior Triangle of the Neck: Nerves and Vessels of the Carotid Triangle" * - "Oral Cavity: The Submandibular Gland and Duct" * () * * Salivary gland cancer from American Cancer Society at http://www.cancer.org/cancer/salivaryglandcancer/detailedguide/salivary-gland-cancer-what-is-salivary-gland-cancer {{Authority control Glands of mouth Otorhinolaryngology