Profile
Settings
Refer your friends
Sign out
Structure
Each submandibular gland is divided into superficial and deep lobes, which are separated by the mylohyoid muscle, which lies superior to the digastric muscles:
The mylohyoid muscle runs beneath the superficial lobe, which makes up the majority of the gland.
The deep lobe is the smallest of the two lobes.
Secretions enter the deep section of the submandibular duct, then hook around the posterior edge of the mylohyoid muscle and travel laterally on the superior surface. The lingual nerve next crosses the excretory ducts, which drain into the sublingual caruncles, which are tiny prominences on either side of the lingual frenulum, as well as the primary sublingual duct. The gland can be palpated (felt) inferior and posterior to the mandible’s body, migrating inward from the mandible’s inferior border near its angle when the head is turned forwards.
Microanatomy
Adenomeres, the gland’s secretory units, are found in smaller lobules inside lobes. Each adenoma has one or more acini, or alveoli, which are tiny clusters of cells that secrete into a duct. Each adenomere’s acini are made up of serious or mucous cells, with serous adenomeres predominating. Some mucous adenomeres may also be capped by a serous demilune, a half-moon-shaped layer of lysozyme-secreting serous cells.
The submandibular gland, like other exocrine glands, can be classed based on the microscopic structure and arrangement of its secretory cells. Submandibular glands are classed as branched tubuloacinar glands because the glands are branched and the tubules creating the branches contain secretory cells. The submandibular gland is also a mixed gland, as the secretory cells are of both serous and mucous types, and the exudate is primarily mucous, even though the majority of the cells are serous. Long striated ducts and short intercalated ducts are present.
The submandibular gland’s secretory acinar cells serve several purposes. Because mucous cells are the most active, saliva, which is mucoid, is the main product of the submandibular glands. Mucin is secreted by mucous cells, which helps to lubricate the food bolus as it moves through the oesophagus. Salivary amylase, which aids in the digestion of starches in the mouth, is also produced by the serous cells. The extremely active acini of the submandibular gland account for the majority of the salivary volume. The remaining glands are the parotid and sublingual glands.
Blood supply
The gland is supplied with blood through the face and lingual arteries. Sublingual and submental arteries supply the gland, and common facial and lingual veins drain it.
Lymphatic drainage
The lymphatics that drain from the submandibular gland first go to the submandibular lymph nodes, then to the jugulo-digastric lymph nodes.
Development
The submandibular salivary glands arise later in prenatal development than the parotid glands, in the sixth week. They emerge from epithelial buds in the sulcus surrounding the primitive mouth’s sublingual folds on both sides. Solid cords grow posteriorly, lateral to the developing tongue, branching from the buds. The cords of the submandibular gland eventually branch out and become canalised, forming the ductal portion. At 12 weeks, the rounded terminal ends of the cords mature into submandibular gland acini, and secretory activity via the submandibular duct begins at 16 weeks. The creation of additional acini maintains the growth of the submandibular gland after birth. A linear groove forms on both sides of the tongue and closes over to form the submandibular duct.
Function
The submandibular gland secretes a slew of hormones that influence systemic immunological and inflammatory responses and regulate systemic inflammatory responses. Early research into variables involved in the cervical sympathetic trunk-submandibular gland (CST-SMG) axis led to the identification of the submandibular gland peptide-T, a seven-amino-acid peptide. SGP-T has been shown to exhibit biological activity and thermoregulatory characteristics in the presence of endotoxins. SGP-T, a submandibular gland isolate, displayed immunoregulatory features and potential involvement in modifying the CST-SMG axis and was later proven to play a key role in inflammation management.
Clinical significance
Due to the distinct nature of the saliva it produces and the convoluted route of the submandibular duct to its ductal opening for a substantial upward distance, the submandibular gland accounts for 80% of all salivary duct calculi (salivary stones or sialolith). The submandibular gland is one of the three major salivary glands in the mouth. The parotid and sublingual glands are the other two types of salivary glands.
What causes sub-mandibular swelling?
Tiny stones hinder the channels that channel saliva into the mouth, resulting in swollen submandibular glands. The salts in saliva, according to the Merck Manual, can cause these stones to form, especially if a person is dehydrated.
What causes submandibular gland pain?
Tiny stones clog the channels that channel saliva into the mouth, causing swollen submandibular glands. These stones can form from the salts in saliva, according to the Merck Manual, especially if a person is dehydrated.
Conclusion
Because saliva is produced by the salivary glands, they serve a crucial function in digesting. Saliva aids in the moistening of food so that it can be swallowed more readily. It also contains an enzyme called amylase, which aids in the digestion of starches in the diet.
