Parotid salivary duct. Projection of the excretory duct of the parotid salivary gland

23.1. ANATOMY AND PHYSIOLOGY OF THE LARGE SALIVARY GLANDS

Salivary glands - This is a group of secretory organs of various sizes, structures and locations that produce saliva. There are small and large salivary glands. Minor (small) salivary glands are located in the mucous membrane of the oral cavity, according to their location they are distinguished: labial, buccal, palatine, lingual, gingival, and also these glands are located in the mucous membrane of the nasopharynx and tonsils. TO major salivary glands relate parotid, submandibular And sublingual glands.

Rice. 23.1.1. Parotid gland (according to V.P. Vorobyov, 1936).

The skin, subcutaneous muscle of the neck, parotid-masticatory fascia, nerves and partially vessels were removed.

I - zygomatic muscle; 2 - circular muscle of the eye; 3- excretory duct of the parotid gland; 4- additional lobules of the gland; 5- chewing muscle; 6 - parotid gland; 7- superficial temporal artery; 8 - superficial temporal vein; 9- sternocleidomastoid muscle;

10 - external carotid artery;

II - external jugular vein; 12 - hyoid bone; 13 - submandibular gland; 14 - digastric muscle; 15 - facial vein; 16 - facial artery; 17 - triangular muscle of the mouth; 18 - buccal muscle.

parotid gland(glandula parotis) - a paired alveolar serous salivary gland located in the parotid-masticatory region. It is the largest of all salivary glands. It is located in the retromaxillary fossa and protrudes slightly beyond its limits (Fig. 23.1.1). The boundaries of the gland are: above- zygomatic arch and external auditory meatus; behind- mastoid process of the temporal bone and sternocleidomastoid muscle; ahead- covers the posterior segment of the masticatory muscle itself; downward- falls slightly below the angle of the lower jaw; from the medial side- the styloid process of the temporal bone with muscles starting from it and the wall of the pharynx. The parotid gland is divided into two lobes: superficial and deep. The average weight of the gland is 20-30 g. In the unchanged state, the gland is poorly palpable under the skin, because surrounded on the outside by a dense and continuous connective tissue capsule, and on the medial side, the capsule is thinner and discontinuous (in this way, the parotid gland communicates with the peripharyngeal space). In places where the capsule is expressed, it is firmly fused with the muscles and fascia. Numerous processes go from the capsule of the gland into its thickness, which form the stroma of the gland and divide it into separate, but firmly connected into the total mass of lobules. The small salivary ducts of the lobules merge into larger (interlobular) ducts, and then gradually merge into ever larger ducts and eventually unite into the parotid excretory duct. An additional duct flows into this duct at the anterior edge of the masticatory muscle from the additional lobe of the parotid gland, which is located above. An additional proportion is found in 60% of patients.

Rice. 23.1.2. Morphological structure of the parotid gland: a) in a child; b) in adolescence; c) in middle age; d) old age (there is fatty degeneration and sclerosis of the parenchyma).

The external carotid artery passes through the thickness of the gland (gives off its branches - a. temporalis superficialis And a. maxillahs), veins - v. parotideae anteriores And posterhores, which merge into v. facialis, facial nerve, ear-temporal nerve, as well as sympathetic and parasympathetic nerve fibers. Around the parotid gland and in its thickness are the lymph nodes (section 9.2, volume I of this Guide).

The length of the extraglandular part of the excretory duct usually does not exceed 5-7 cm, the diameter (width) is 2-3 mm. In older people it is wider than in children. Usually the excretory duct departs at the border of the upper and middle thirds of the gland. The transition of the intraglandular part of the duct to the extraglandular part is located quite deep in the gland. Therefore, a part of the parotid gland is located above the extraglandular part of the excretory duct. The direction of the excretory duct may vary, i.e. it is straight, arched, curving, and very rarely forked. The excretory duct of the parotid gland runs along the outer surface m. masseter, leans over her front to
Paradise and passing through the fatty tissue of the cheek and the buccal muscle opens on the mucous membrane of the cheek in the vestibule of the mouth (opposite the second upper molar).

Rice. 23.1.3. The structure of the parenchyma of the gland with the presence of an intraglandular lymph node. Microphotogram of parotid tissue. Hematoxylin-eosin stain.

Macroscopically, the parotid gland, depending on the blood supply, has a pinkish or yellowish-gray color, a bumpy surface and a moderately dense texture. In older people, the glands are paler, heavy, of uneven density.

The main structural units of the parenchyma of the parotid gland are the alveolar terminal secretory sections (acini), compactly located in the lobules and consisting of cells of the glandular epithelium, small ducts are located between them. The terminal secretory sections are represented by pyramidal cylindrical cells, with a wide base adjacent to the basement membrane (Fig. 23.1.2 - 23.1.3). Near the orifice are mucus-secreting goblet cells that form a chemical barrier to microbes ascending through the ducts into the gland. With age, the zones of interlobular connective tissue increase, areas of fatty degeneration of the parenchyma appear with a decrease in the mass of the terminal secretory sections and atrophy of the glandular tissue.

A large experimental material gives grounds for the assertion that the parenchyma of the salivary glands produces biologically active substances such as hormones: parotin - nerve and epithelial growth factor, thymocin- transforming factor and others (Fleming H.S., 1960; Suzuki J. et al., 1975; Rybakova M.G., 1982, etc.).

In practically healthy people, within one hour, the parotid gland produces from 1 to 15 ml of unstimulated saliva (about 5 ml on average). Normally, the pH of saliva of the parotid gland ranges from 5.6 to 7.6 (Andreeva T.B., 1965). According to the composition of the secret, the parotid gland belongs to purely serous glands.

submandibular gland (glandula submandibularis) - a paired alveolar, in some places tubular - alveolar salivary gland, which is located in the submandibular triangle of the neck (Fig. 23.1.4).

It is located between the base of the lower jaw and both abdomens of the digastric muscle. Its upper-lateral part of the gland is adjacent to the fossa of the same name (fossa of the submandibular gland) of the lower jaw, from behind reaching its angle, approaching the posterior abdomen m. digastricus, to the stylohyoid, to the sternocleidomastoid and medial pterygoid muscles, and in front it comes into contact with the hyoid-lingual and with the anterior belly of the digastric muscle. For a considerable length of its front part, the iron is covered m. mylohyoideus, and behind it bends over its rear edge and comes into contact with the sublingual gland. Near the angle of the mandible, the submandibular gland is located close to the parotid gland.

Rice. 23.1.4. Submandibular and sublingual glands, inside view (according to V.P. Vorobyov,

Median incision of the floor of the mouth and lower jaw; the mucous membrane is removed; ducts of glands are allocated.

1- medial pterygoid muscle; 2- lingual nerve; 3- small sublingual ducts; 4 - the mouth of the excretory duct of the submandibular gland; 5- large sublingual duct; 6- body of the lower jaw; 7- sublingual gland; 8 - excretory duct of the submandibular gland; 9- jaw - hyoid muscle; 10 - submandibular gland.

Thus, the bed of the submandibular gland is limited: from within the diaphragm of the floor of the mouth and the hyoid-lingual muscle; outside- the inner surface of the body of the lower jaw; from below- anterior and posterior belly of the digastric muscle and its intermediate tendon.

The excretory duct of the submandibular gland departs, as a rule, from its upper medial section. Bending over the posterior edge of the maxillo-hyoid muscle, it is located on the lateral side of the hyoid-lingual muscle, and then passes between it and the maxillo-hyoid muscle. Next comes between the sublingual gland and the more medially located chin-lingual muscle. The excretory duct opens on the mucous membrane of the bottom of the mouth on the side of the frenulum of the tongue. At the site of the outlet of the duct, the mucous membrane forms an elevation, which is called sublingual meat (caruncula sublingualis). The length of the excretory duct of the submandibular gland does not exceed 5-7 cm, and the width (diameter) of the lumen is 2-4 mm (A.V. Klementov, 1960). The mouth of the excretory duct is much narrower than in the parotid gland (PA. Zedgenidze, 1953; L. Sazama, 1971).

The capsule of the gland is formed by splitting the surface sheet of the own fascia of the neck. The capsule is thick on the outside and thin on the inside. Loose fatty tissue is located between the capsule and the gland, which makes it easy to peel the gland (in the absence of inflammatory changes) from the surrounding soft tissues. Lymph nodes are located in the fascial bed of the gland (Section 9.2, Volume I of this Guide). The weight of the gland averages from 8 to 10 g, and after the age of 50, the weight of the gland decreases (A.K. Arutyunov, 1956). The consistency of the gland is of moderate density, the color is pinkish-yellow or gray-yellow.

The submandibular gland is supplied with blood by the facial, lingual, and submental arteries. The facial artery enters the posterior submandibular triangle (departs from the external carotid artery). It is covered by the posterior belly of the digastric muscle and the awl by the hyoid muscle. In this place, it goes obliquely up and forward, often located under the gland. Less often - passes behind the gland, very rarely lies on the gland. Along the edge of the lower jaw, along the outer surface of the gland, the submental artery departs from the facial artery, which gives off small branches to the gland. In the posterior part of the lower outer surface of the gland, between it and the aponeurosis, there is a facial vein.

lingual nerve, leaving the gap between the pterygoid muscles, lies directly under the mucous membrane of the bottom of the mouth and passes between it and the posterior pole of the submandibular gland. The position of the lingual nerve must be taken into account when performing surgical interventions on the excretory duct of the gland. hypoglossal nerve enters the submandibular triangle between the posterior belly of the digastric muscle and the outer surface of the hyoid-lingual muscle. Being on the muscle, the nerve descends, forming an arc, convex downwards and covered by the gland. In chronic inflammatory processes in the submandibular gland, the nerve may be in adhesions and damage may occur during the extirpation of the gland.

facial nerve, or rather its marginal branch, runs about 1 cm below the lower edge of the lower jaw. Therefore, the incision in the submandibular region is made 1.5-2 cm below the lower edge of the jaw. The secretory fibers of iron are received from the vegetative submandibular node (ganglion).

In healthy people, from 1 to 22 ml of unstimulated saliva is produced within an hour (on average, about 12 ml). In the saliva of the submandibular gland, pH ranges from 6.9 to 7.8 (T.B. Andreeva, 1965).

By the nature of the secret, the submandibular gland is mixed, i.e. seromucosal.

The epithelium of the ducts is the same as in the parotid gland, with the only difference being that it is often multi-layered (P. Rother, 1963). This may explain the significant resistance to the pressure of the contrast (in sialography) or washing fluid (in the treatment of inflammatory diseases of the gland).

sublingual gland{ g. sublingualis) - steam tubular - alveolar salivary gland located at the bottom of the oral cavity. The sublingual gland is located in the cellular space of the floor of the mouth between the frenulum of the tongue and the projection of the wisdom tooth. Outside the gland is adjacent to the inner surface of the body of the lower jaw (to the recess for the sublingual gland). From within borders on the hyoid-lingual and genio-lingual muscles (the lingual nerve, the terminal branches of the hypoglossal nerve, the lingual artery and vein, the excretory duct of the submandibular gland adjoin it). Bottom- located in the gap between the maxillo-hyoid and chin-hyoid muscles. Above- mucous membrane of the bottom of the mouth. The gland is surrounded by a thin capsule, from which septa extend, dividing the gland into lobules (Fig. 23.1.4).

The weight of the gland is on average from 3 to 5 g. Its dimensions vary (the length is on average from 1.5 to 3 cm). The color of the gland is gray - pink. The gland has a lobular appearance, especially in the posterolateral sections, and its separate ducts, which are called small sublingual ducts. The latter open along the sublingual fold at the bottom of the mouth. The main mass of the gland is collected in one common duct, which flows into the excretory duct of the submandibular gland near its mouth. The common excretory duct is 1 to 2 cm long and 1 to 2 mm in diameter. Rarely, the sublingual duct can open on its own near the orifice of the submandibular duct. The gland is supplied with blood by the hyoid artery (departs from the lingual artery), venous outflow is carried out through the hyoid vein. It receives sympathetic innervation from the autonomic hyoid ganglion. Innervation - from the lingual nerve.

According to the composition of the secret, the sublingual gland refers to mixed serous-mucous glands.

In an adult, saliva secretion is about 1000-1500 ml per day, and a lot depends on how this secretion is stimulated by food and other external and internal impulses (L. Sazama, 1971).

According to the studies of W. Pigman (1957), 69% of saliva is secreted from the major salivary glands by the submandibular glands, 26% by the parotid and 5% by the sublingual glands.

The secretion of the small salivary glands is assessed using filter paper of a certain mass, which is weighed after the study (V.I. Yakovleva, 1980). The average number of secreted small salivary glands is determined in the area of ​​the mucous membrane equal to 4 cm 2 . Indicators that are normal in apparently healthy people are presented in Table 9.1.2 (Volume I of this Guide).

Saliva contains lysozyme (see Table 9.1.1, Volume I of this Guide), amylase, phosphatases, proteins, sodium, potassium, calcium, phosphorus, magnesium ions, parotin and other chemicals, endocrine factors, enzymes.

In conclusion, I want to remind you that the names of the ducts of the large salivary glands are also associated with the names of scientists. So the duct of the parotid gland is commonly called stenon(Stenonii), submandibular - Wharton(Wartonii), the main duct of the sublingual gland - bartalin(Bartalinii), and the small ducts of the sublingual gland - rivinium(Rivini).

Humans have small and large salivary glands. The group of small glands includes buccal, labial, molar, palatine and lingual. They are located in the thickness of the oral mucosa. Small glands are divided into 3 types according to the nature of the secreted saliva - mucous, serous or mixed. The major salivary glands are the parotid, sublingual, and submandibular glands.

Topography of the parotid gland

The parotid glands, the largest of all, produce a protein secret. The glands are located in the retromaxillary fossae, adjacent in depth to the muscles coming from the styloid process, the pterygoid and digastric muscles. The upper edge of the gland is located at the external auditory meatus and the membranous part of the temporal bone, the lower edge is near the angle of the mandible. The superficial part of the glands lies under the skin, covers the chewing muscle and the branch of the lower jaw. Outside, the parotid glands have a dense fibrous capsule, fused with the surface layer of the own fascia of the neck.

The tissue of the organ is represented by glandular lobules having an alveolar structure. The walls of the alveolar vesicles are composed of secretory cells. Intercalary ducts lie between the lobules in the layers of fibrous tissue. With one pole, the secretory cells face the ducts. The bases of the cells are adjacent to the basement membrane, in contact with myoepithelial elements capable of contraction. The flow of saliva from the ducts is stimulated by the contraction of myoepithelial cells.

Intralobular striated ducts are lined from the inside with a layer of prismatic epithelium. Connecting, the striated ducts form interlobular ducts, which have a stratified squamous epithelium. The common excretory duct of the gland is formed by the fusion of the interlobular ducts. Its length is 2–4 cm. The duct lies on the surface of the buccal muscle below the arch of the zygomatic bone by 1–2 cm. At the anterior edge of the muscle, it pierces the fat body and the muscle itself, opening in front of the mouth opposite 1–2 upper molars ( large molar). The neurovascular bundle runs through the parotid gland. It contains the external carotid, superficial temporal, transverse, and posterior auricular arteries; facial nerve and retromaxillary vein.

Topography of the submandibular gland

The submandibular gland secretes saliva of a mixed protein-mucous character. It has a lobed structure. The gland is located in the submandibular fossa, bounded from above by the maxillary-hyoid muscle, behind by the posterior belly of the digastric muscle, in front by the anterior belly of this muscle, and from the outside by the subcutaneous muscle of the neck. The gland is covered with a capsule, which is a layer of the own fascia of the neck. The internal structure of the gland and its ducts is similar to the structure of the parotid gland. The excretory duct of the submandibular gland exits on its medial surface and lies between the maxillo-hyoid and hyoid-lingual muscles.

Topography of the sublingual gland

The sublingual salivary gland secretes mainly a mucous secret (mucin), is formed by lobules that have an alveolar structure. The gland is located under the lateral part of the tongue on the geniohyoid muscle. The ducts of the sublingual and submandibular glands open on both sides of the frenulum of the tongue.

Embryonic development

The salivary glands are formed from the epithelium of the oral cavity of the embryo, growing into the underlying mesenchyme. By the 6th week of the embryo's life, the submandibular and parotid glands are laid, at the 7th week - the sublingual glands. The secretory sections of the glands are formed from the epithelium, and the connective tissue septa between the lobules are formed from the mesenchyme.

Functions

The saliva secreted by the glands has a slightly alkaline reaction. The secretion of the glands includes: inorganic salts, water, mucus, lysozyme, digestive enzymes - maltase and ptyalin. Saliva is involved in the breakdown of carbohydrates, moisturizes the mucous membrane, softens food and has a bactericidal effect on microorganisms.

Inflammatory diseases

The common name for inflammation of the salivary glands is sialadenitis. Inflammatory diseases in the salivary glands occur when an infection enters with blood, lymph, or ascending from the oral cavity. The process of inflammation can be serous or purulent.

A viral infectious disease of the parotid gland is mumps or mumps. If the child's parotid glands are symmetrically swollen and hurt, these are symptoms of mumps. A complication of mumps suffered in childhood is male infertility. The mumps virus damages not only the salivary glands, but also the germ cell tissue of the testicles. Prevention of mumps and its complications is the vaccination of preschool children against mumps.

Autoimmune inflammation with the accumulation of lymphoid cells in the tissues of the salivary glands develops in Sjögren's syndrome ( group of diffuse connective tissue diseases). Sjögren's syndrome is an autoimmune lesion of exocrine glands, joints and other connective tissue structures. The causes of the disease are considered viral infections, coupled with a genetic predisposition.
Stone sialadenitis - the formation of a stone in the salivary duct and reactive inflammation of the organ. A duct stone obstructs the flow of saliva and can cause a retention cyst to form.

Other reasons for the formation of retention cysts of the salivary glands: trauma, inflammation of the ducts, followed by their blockage and impaired saliva outflow. A cyst with a mucous (mucoid) secretion is called a mucocele.

Damage

Facial injuries may be accompanied by damage to the tissue and excretory ducts of the parotid gland. These injuries are dangerous by the formation of salivary fistulas, narrowing or obstruction of the excretory duct, which leads to stagnation of saliva. Acute damage to the organ is determined by the following symptoms: salivation from the wound, the formation of salivary flow - the accumulation of saliva under the skin. Treatment of the consequences of trauma to the parotid gland - suturing the wound, the operation of restoring the mouth of the duct when it is overgrown, surgical plastic surgery of salivary fistulas.

Tumor diseases

From the epithelium of the ducts and secretory cells, true tumors of the salivary glands can develop. A benign neoplasm is called an adenoma, a malignant neoplasm is called cancer or sarcoma. Tumors of the salivary glands in the initial stages do not hurt. Therefore, a unilateral painless enlargement of the salivary gland is an indication for consultation with an oncologist and additional research.

Classification of neoplasms of the salivary glands according to the nature of tumor growth:
benign forms;
locally destructive forms;
malignant forms.

Of the benign tumors, the most common pleomorphic adenoma, which has a mixed tissue character. It is characterized by slow growth over many years. The tumor can reach a large size, but is painless and does not metastasize. Malignancy of pleomorphic adenoma develops in 3.6-30%.

Indications for operations on the salivary glands:
the formation of stones in the salivary ducts;
benign and malignant tumors.

Treatment of cysts and tumors of the salivary glands - removal of the affected organ. The remaining healthy glands provide the secretion of saliva.

Diagnostic methods

For effective treatment of salivary gland cancer, the condition of the lymph nodes and surrounding tissues is assessed for the presence of metastases. Additional studies are needed to obtain information about the location, number and size of stones or tumors:
contrast radiography - sialography;
duct probing;
cytological examination of the secret;
Ultrasound - ultrasound examination;
magnetic resonance or computed tomography;
biopsy, specifying the histological type of tumor.

About transplant

Scientists have developed a technique of autotransplantation - transplantation of one of the patient's own salivary glands under the skin of the temple. The operation allows you to effectively treat the "dry eye" syndrome, significantly improving the condition of patients. Clinical trials were conducted at the University of Sao Paulo in Brazil, where 19 people were operated on. The results of the operations showed a good clinical effect. Surgeons from the University of Napoli and other medical centers in Germany also got good results.

Experimental transplantation of embryonic tissue of the major salivary glands in laboratory animals ( guinea pigs) was performed at the Belarusian State Medical University in 2003. The work of medical scientists in this direction continues.

As already mentioned, most often tumors located in the superficial lobe of the parotid, followed by the submandibular salivary gland and, then, the sublingual and minor salivary glands. Since the optimal treatment for benign salivary gland tumors is still surgical removal, understanding the anatomy of the salivary glands is essential to avoid complications.

Salivary glands begin to form at 6-9 weeks of intrauterine life. The major salivary glands are derived from the ectoderm, while the minor salivary glands may be derived from either the ectoderm or the endoderm. Since the capsule around the submandibular salivary gland is formed earlier than around the parotid, lymph nodes sometimes migrate into the thickness of the latter. This explains the fact that in the parotid salivary gland, in contrast to the submandibular gland, lymphogenous metastases can occur.

excretory unit any salivary gland consists of an acinus and a duct. According to the nature of the secretion secreted, the acini are divided into serous, mucous and mixed. From the acini, the secret enters first into the intercalary ducts, then into the striated ducts, and finally into the excretory ducts. Around the acini and intercalary ducts are myoepithelial cells that facilitate the passage of saliva through the ducts.

Parotid salivary gland secretes mainly serous secretion, sublingual and minor salivary glands - mucinous, submandibular gland - mixed.

Although in fact parotid gland It is represented by only one lobe, but from a surgical point of view, a superficial lobe located lateral to the facial nerve and a deep lobe located medial to the facial nerve are distinguished in it. The parasympathetic innervation of the gland is provided by preganglionic fibers originating from the inferior salivary nucleus, which then, as part of the glossopharyngeal nerve (CN IX), exit the cranial cavity through the jugular foramen.

(a) Large salivary glands.
(b) Anatomy of the submandibular triangle. The relationship of the submandibular salivary gland with important vessels and nerves is shown.
The hypoglossal nerve runs lower and deeper from the gland, the facial artery and vein higher and deeper.

After leaving the cranial cavity preganglionic fibers separate from the glossopharyngeal nerve, form the tympanic nerve, and re-enter the cavity through the inferior tympanic canaliculus. In the cavity of the middle ear, they pass over the cape of the cochlea, and then leave the temporal bone as a small stony nerve. The small stony nerve leaves the cranial cavity through a round opening, where then its preganglionic fibers form synapses with the ear ganglion. Postganglionic fibers in the auricular-temporal nerve innervate the parotid salivary gland.

Excretory duct of the parotid gland is called the Stensen duct. It runs in a horizontal plane about 1 cm below the zygomatic bone, often in close proximity to the buccal branch of the facial nerve. Anterior to the chewing muscle, the duct pierces the buccal muscle and opens into the oral cavity at the level of the second upper molar. The iron receives its arterial blood supply from the system of the external carotid artery, the venous outflow is carried out into the posterior facial vein. As mentioned above, in the thickness of the parotid gland there are lymph nodes, the lymph flow from which occurs in the lymph nodes of the jugular chain.

parotid gland located inside the so-called parotid space in the form of a wedge, bounded from above by the zygomatic bone; in front of the masticatory muscle, lateral pterygoid muscle and the branch of the lower jaw; from below by the sternocleidomastoid muscle and the posterior belly of the digastric muscle. The deep lobe lies lateral to the parapharyngeal space, styloid process, stylomandibular ligament, and carotid sheath. The gland is enveloped by the parotid fascia, which separates it from the zygomatic bone.

IN parotid space facial, ear-temporal and large ear nerves are located; superficial temporal and posterior facial veins; external carotid, superficial temporal and internal maxillary arteries.

After leaving stylomastoid foramen facial nerve(CN VII) goes anteriorly and enters the parotid salivary gland. Before entering the thickness of the gland, it gives branches to the posterior ear muscle, the posterior belly of the digastric muscle and the stylohyoid muscle. Immediately after entering the gland, the nerve divides into two main branches: superior and inferior (crow's foot). As a rule, the upper branch divides into the temporal and zygomatic nerves, and the lower branch into the buccal, marginal mandibular and buccal nerves. Knowledge of these anatomical features is necessary in order not to damage the nerve during operations on the parotid salivary gland.

Anatomy of the facial nerve after its exit from the stylomastoid foramen.
In the parenchyma of the parotid salivary gland, the nerve divides into several branches.
Note that the stenonic duct runs along with the buccal branch of the nerve.

The ducts of three pairs of glands open into the oral cavity, which produce saliva of a slightly alkaline reaction (pH 7.4 - 8.0), containing water, inorganic substances (salts), mucin (mucopolysaccharides), enzymes (ptyalin, maltase, lipase, peptidase, proteinase ), lysozyme (antibiotic substance). Saliva not only moisturizes the mucous membrane, but also soaks the food bolus, participates in the breakdown of nutrients and acts on microorganisms as a bactericidal agent.

parotid gland
Parotid salivary gland (gl. parotis) steam room, the largest of all salivary glands, produces saliva, which contains a lot of protein. The gland is located in the fossa retromandibularis, where in depth it is adjacent to the pterygoid muscles and muscles starting from the styloid process (mm. stylohyoideus, stylopharyngeus and the posterior belly of m. digastricus), at the top it extends to the external auditory canal and pars tympanica of the temporal bone, below it is at the level angle of the lower jaw (Fig. 224). The superficial part of the gland is located under the skin, covers m. masseter and branch of the lower jaw. The gland is covered with a dense connective tissue capsule, which is connected to the superficial sheet of the fascia of the neck. Its parenchyma consists of glandular lobules with an alveolar structure. The walls of the alveoli are formed by secretory cells. Between the lobules in the layers of connective tissue are excretory ducts. Secretory cells with one pole facing the intercalary ducts, and the other - to the basement membrane, where they come into contact with myoepithelial cells capable of contraction. Thus, saliva flows out of the duct due not only to the end pressure vis a tergo, but also due to the contraction of myoepithelial cells in the end sections of the gland.

gland ducts. Intercalary ducts are located in the alveoli formed by secretory cells. The striated ducts are larger, lined with a single-layer cylindrical epithelium and are also located inside the lobules. The union of many striated ducts forms larger interlobular ducts lined with stratified squamous epithelium.

The common excretory duct (ductus parotideus), 2-4 cm long, begins by confluence of all interlobular ducts, is located 1-2 cm below the zygomatic arch, on the surface of the masticatory muscle. At the front edge of it, it pierces the fat body and the buccal muscle, opens on the eve of the mouth at the level of the second (first) large molar of the upper jaw.

The external carotid, superficial temporal, transverse, posterior auricular arteries, facial nerve and retromaxillary vein pass through the parotid gland.

224. Salivary and mucous glands of the vestibule and oral cavity on the right. The lower jaw is excised.
1 - glandulae buccales; 2-gl. labiales; 3 - labium superius; 4 - lingua; 5-gl. lingualis anterior; 6 - labium inferius; 7 - caruncula sublingualis; 8 - ductus sublingulis major; 9 - mandible; 10 - m. genioglossus; 11 - m. digastricus; 12-gl. sublingualis; 13 - m. mylohyoideus; 14 - ductus submandibularis; 15-gl. submandibularis; 16 - m. stylohyoideus; 17 - m. digastricus; 18 - m. masseter; 19-gl. parotis 20-f. masseterica et fascia parotidea; 21 - ductus parotideus; 22-gl. parotis accessoria.

submandibular gland
The submandibular gland (gl. submandibularis) has a lobed structure, produces a protein-mucous secret. The gland is localized under the edge of the lower jaw in the regio submandibularis, which is limited from above by m. mylohyoideus, behind - the posterior abdomen of the digastric muscle, in front - its anterior abdomen, outside - platysma. The gland is covered with a connective tissue capsule representing part f. colli propria. The general structure of the gland and its ducts is similar to the parotid gland. The common duct of the submandibular gland exits on its medial surface, then penetrates between m. mylohyoideus and m. hyoglossus and reaches an elevation under the tongue - caruncula sublingualis.

sublingual gland
The sublingual gland (gl. sublingualis) produces a mucous secret (mucin); located under the tongue and its lateral part on m. geniohyoideus. It has an alveolar structure, formed from lobules. The common duct of the gland and smaller ducts open under the tongue on the sides of the frenulum sublingualis.

The common duct connects with the terminal part of the duct of the submandibular gland.

Radiographs of the salivary glands
After the introduction of a contrast agent into the duct of any salivary gland (sialography), the contour and architecture of the ducts can be used to judge the state of the gland. The contours of the duct are clear, have a uniform diameter, the architecture of the lobular ducts is correct, there are no voids; as a rule, ducts of the 5th, 4th, 3rd, 2nd and 1st order, having a tree-like shape, are easily filled (Fig. 225). All ducts are freed from the contrast agent within the first hour after injection.

225. Lateral sialogram of the left parotid salivary gland.
1 - duct; 2 - intraglandular salivary ducts; 3 - lower jaw; 4 - hyoid bone.

Embryogenesis of the salivary glands
The salivary glands develop from the epithelium of the oral cavity and grow into the surrounding mesenchyme. The parotid and submandibular glands appear at the 6th week of the intrauterine period, and the sublingual - at the 7th week. The terminal sections of the glands are formed from the epithelium, and the connective tissue stroma, which divides the gland rudiment into lobes, is from the mesenchyme.

Phylogeny of the salivary glands
Fish and aquatic amphibians do not have salivary glands. They appear only in land animals. Terrestrial amphibians acquire internasal and palatine glands. In reptiles, sublingual, labial and dental glands additionally arise. The dental glands in snakes are transformed into tubular poisonous glands located in the thickness of the chewing muscle, and their ducts are connected to the canal or groove of the front teeth. With the contraction of the masticatory muscle, the poison of the gland is squeezed out into the duct. Birds have sublingual glands and several small palatine glands that produce mucous saliva. Mammals have all the salivary glands, just like humans.

Excretory duct of the parotid salivary gland. Source: Medical Dictionary... medical terms

STENON FLOW- (Stensen s duct) excretory duct of the parotid salivary gland ... Explanatory Dictionary of Medicine

By this name are meant very diverse glandular appendages of the oral cavity and pharynx. So, in worms, various unicellular glands called S., pharyngeal and septal glands open into the pharynx. Then they have a peculiar function...

V. M. Sh. To S. glands (gl. Salivales), there are three pairs of glands: the parotid gland, submandibular and sublingual, of which the first are located outside, and the last inside the oral cavity. The parotid gland (glandula parotis) belongs to the most ... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Large human salivary glands: 1. About ... Wikipedia

The location of Bish's fat body (colored yellow) relative to the bone and soft tissue anatomical structures of the face ... Wikipedia

Oral cavity- (cavum oris) (Fig. 151, 156, 194) is the beginning of the digestive apparatus. In front, it is limited by the lips, above by the hard and soft palate, below by the muscles that form the bottom of the oral cavity and the tongue, and on the sides by the cheeks. Opening the mouth... Atlas of human anatomy

ABSCESS- ABSCESS, abscess, or abscess, a limited accumulation of pus in tissues or organs. In other words, an abscess is a cavity filled with pus in tissues and organs in places where no cavity existed before. Pathological anatomy. ... ...

- (galandulae oris) There are small and large salivary glands (Fig. 1). Small S. (labial, buccal, molar, lingual and palatine) are located in the oral mucosa. By the nature of the allocated secret, small C. well. divided into serous, ... ... Medical Encyclopedia

parotid gland- (glandula paro tis), the largest of the salivary glands, is located on the face, in a deep cavity behind the ascending branch of the lower jaw, in the so-called retromaxillary fossa (fossa heteromandibularis). The shape of the gland is entirely adapted to the walls of this ... Big Medical Encyclopedia