The submandibular gland is the paired organ of the digestive system located in the oral cavity that produces saliva. The purpose of the latter is to wet and disinfect the food lump, as well as the primary hydrolysis of certain carbohydrates (for example, starch). This organ belongs to the group of three large salivary glands (along with the hyoid and parotid).
General characteristics of the organ
The submandibular gland (lat.glandula submandibularis) is a secretory organ with a complex alveolar-tubular structure, which is shaped like a spherical mass the size of a walnut and weighing about 15 grams (0.84 in newborns).
The length of the gland in an adult is 3.5-4.5 cm, the width is 1.5-2.5, and the thickness is 1.2-2 cm. The structure of the organ is represented by lobes and segments, between which are layers of connective tissue containing nerves and blood vessels.
Glandula submandibularis belongs to the salivary glands of mixed secretion, since the product secreted by it consists of two components: serous (contains a large amount of protein) and mucous.
Outside, the organ is covered with a thin connective tissue capsule formed by the surface plate of the fascia of the neck. The connection between the gland and the membrane is quite loose, so they can be easily separated from each other. The capsule contains the facial artery (in some cases, the vein).
The ducts of the submandibular salivary gland are divided into 3 types:
- intralobular;
- interlobular;
- interlobar.
These species sequentially pass into each other, gathering in a common output channel. The ducts of the first type depart from the lobules of the gland, and more precisely - from their terminal (or secretory) departments. The latter are divided into 2 types:
- serous - secrete protein secretion and have the same structure as in similar structures of the parotid gland;
- mixed - consist of mucocytes and serocytes (each group of cells produces its own secret).
Mucocytes are located in the central zone of the terminal sections, and serocytes located on the periphery form the Jauzzi semi-moon.
In the series of three large salivary glands, the submandibular is second in size and the first in the amount of secreted substance. The work of this paired organ accounts for 70% of the total volume of saliva excreted in the oral cavity when at rest. With stimulated secretion, the parotid gland functions to a greater extent.
Topography
The gland is located deep beneath the lower jaw, from which its name follows. The place where the organ is located is called the submandibular triangle.
The surface of the gland is in contact:
- the medial part - with the sublingual-lingual and stylo-lingual muscles;
- front and rear edges - with the corresponding abdomen of the double-abdominal muscle;
- lateral part - with the body of the lower jaw.
The outer side of the organ borders on the fascia plate of the neck and skin.
Blood supply
The blood supply to the submandibular gland is due to three arteries:
- facial - passes to the body through the capsule and serves as the main nutrient vessel;
- chin;
- lingual.
The vessels departing from the gland with venous blood flow into the chin and facial veins.
Duct
The network of excretory channels extending from the secretory sections of the organ is combined into the duct of the submandibular gland, which originates from the front of the organ and opens on the hyoid papilla, through which saliva enters the oral cavity.
The length of the output channel varies from 40 to 60 mm, and the inner diameter is 2-3 mm in an arbitrary section and 1 mm in the mouth. The duct is most often straight (in rare cases, it has an arched or S-shaped shape).
Inflammatory process
The most common salivary gland pathology is inflammation or, scientifically, sialadenitis. Due to the peculiarities of the location in the oral cavity, this disease is most characteristic of the parotid gland, but it also occurs in the submandibular. Damage to the latter is relatively rare.
Inflammation of the submandibular gland most often has an infectious nature of exogenous (from the oral cavity) or endogenous nature. In the latter case, the pathogen enters the gland from the body itself. There are 3 ways to get this infection:
- hematogenous (through blood);
- lymphogenous (through lymph);
- contact (through tissues adjacent to the gland).
Most often, infection occurs exogenously, in which the mouth of the duct of the gland is the entrance gate for the pathogen. Particles of food can contribute to this.
Inflammation may be caused by:
- bacteria (oral microflora, streptococci and staphylococci);
- Epstein-Barr viruses, herpes, influenza, Coxsackie, mumps, as well as cytomegalovirus, some orthomyxoviruses and paramyxoviruses;
- fungi (found much less frequently);
- protozoa (pale treponema) - characteristic of specific cases.
Weakening of the immune system, surgical operations in the oral cavity, as well as diseases of the maxillofacial area and respiratory pathologies (tracheitis, pharyngitis, pneumonia, tonsillitis, etc.) can contribute to the development of sialadenitis of the submandibular gland.
Classification of Sialadenitis
By the nature of the clinical course, inflammation of the submandibular gland can be acute and chronic. The latter has three forms:
- parenchymal (affects the organ parenchyma);
- interstitial (connective tissue inflamed);
- with damage to the ducts.
An inflammatory disease of the submandibular gland, accompanied by damage to the ducts, is called chronic sialadochitis.
Clinical course and symptoms
In acute sialadenitis in the submandibular gland, the following pathological processes can occur:
- edema;
- increase in volume and compaction of organ tissues;
- infiltration;
- pus formation;
- tissue necrosis followed by scarring;
- a decrease in the amount of saliva secreted (hyposalivation).
Inflammation is accompanied by pain in the affected organ, dry mouth, a general deterioration in well-being, as well as standard signs of intoxication (chills, weakness, fever, fatigue).
Chronic sialoiditis is most often not accompanied by soreness. During an exacerbation of this pathology, the patient may experience salivary colic. With a long chronic course in the gland, reactive-dystrophic changes often develop.