The salivary glands are a special group of exocrine organs that affect the state of the body, its digestive and hormonal systems.
There are the following important functions of salivary glands:
- secretory (release of organic and inorganic substances);
- excretory (excretion of metabolites, salts of heavy metals and some other substances);
- recretory (transient passage of substances from blood to saliva);
- endocrine (isolation of polypeptide proteins which have a common structure with hormones).
Salivary glands produce a secret - saliva - into the oral cavity, which amounts to 0.5 to 1.5 liters per day. During digestion saliva moisturizes food, helping to form a bolus. Secret enzymes like amylase, hyaluronidase, lipase, esterase and others split proteins, fats, carbohydrates and nucleic acids.
Saliva also performs protective and trophic functions:
- washing away food debris;
- formation of a barrier from mucin and antibodies;
- maintaining the acidity (pH) of the oral fluid;
- protection of dental enamel;
- providing local non-specific humoral and cellular immunity;
- destruction of viruses by enzymatic systems.
The important role of the major salivary glands in the regulation of metabolism, adaptive and regenerative processes in the body has also been proven.
The salivary apparatus consists of paired major (the parotid, submandibular, sublingual) and minor salivary glands (the mucous membrane of the lips, the cheeks, the palate, and the tongue).
The major salivary glands include:
- the parotid gland (glandula parotis);
- the submandibular gland (glandula submandibularis);
- the sublingual gland (glandula sublingualis).
The minor salivary glands are localized to the mucous membrane of the lips, the cheeks, the palate, and the tongue.
The major salivary glands.
- The largest of the salivary glands is the parotid gland.
- It is located around the earlobe like a horseshoe and spreads:
- posteriorly - to the mastoid process;
- downwards - to the corner of the lower jaw;
- anteriorly - to the anterior edge of the masseter muscle;
- superiorly - to the level of the zygomatic arch.
- The main excretory duct (the Stenon duct) departs from the parotid gland in its upper part, parallel to the zygomatic arch, pierces the buccal muscle, and opens opposite the second upper molar, on the entrance of the mouth. The length of the extraglandular part of the duct is 5-7 cm, the diameter is 2-3 mm. According to the composition of the secret, the parotid gland is classified as a serous gland. There are lymph nodes in the thickness of the interlobular connective tissue and over the capsule of the gland, in the preauricular region.
- The submandibular gland is much smaller than the parotid gland and is located in the submandibular triangle.
- It is limited:
- on the sides - by the belly of the digastric muscle;
- on top - by the mylohyoid muscle;
- from below - by the skin.
- The gland has a rounded shape; it is covered by a dense capsule. The main excretory duct (the submandibular/Wharton's duct) bends around the posterior edge of the mylohyoid muscle, penetrates into the hyoid region and opens with the salivary papilla at the bottom of the oral cavity behind the lower incisors, on the side of the frenum of the tongue. It is 2-4 mm in diameter and 5-7 cm in length. By the nature of the secretion, the submandibular gland is serous-mucous.
- The sublingual gland is smaller than the submandibular gland. It has an oval shape and is located at the bottom of the oral cavity, between the inner surface of the lower jaw and the side wall of the tongue. It may have an inferior process that penetrates through the mylohyoid muscle into the submandibular region to combine with the submandibular gland. The main excretory duct of the gland flows into the duct of the submandibular salivary gland (but it can also be a separate duct). By the nature of the secret, just like the submandibular gland, it is serous and mucous.