Parotid salivary duct. Projection of the excretory duct of the parotid salivary gland
23.1. ANATOMY AND PHYSIOLOGY OF THE MAJOR SALIVARY GLANDS
Salivary glands is a group of secretory organs of various sizes, structure and location that produce saliva. There are minor and major 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, palatal, lingual, gum, and these glands are also 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 blood vessels were removed.
I - zygomatic muscle; 2 - orbicularis oculi muscle; 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) - 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 canal; behind- mastoid process of the temporal bone and sternocleidomastoid muscle; ahead- covers the posterior segment of the masticatory muscle itself; downwards- falls slightly below the angle of the lower jaw; from the medial side- the styloid process of the temporal bone with the 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 an unchanged state, the gland is difficult to feel under the skin, because it is surrounded on the outer side by a dense and continuous connective tissue capsule, and on the medial side the capsule is thinner and not continuous (in this way the parotid gland communicates with the peripharyngeal space). In places where the capsule is pronounced, it firmly fuses with the muscles and fascia. Numerous processes extend from the capsule of the gland into its thickness, which form the stroma of the gland and divide it into separate, but firmly connected lobules. The small salivary ducts of the lobules merge into larger ones (interlobular), and then gradually unite into increasingly larger ducts and, ultimately, combine into the excretory duct of the parotid gland. An accessory duct from the accessory lobe of the parotid gland, which is located above, flows into this duct at the anterior edge of the masticatory muscle. An additional lobe is detected 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 postehores, which merge into v. facialis, facial nerve, auriculotemporal nerve, as well as sympathetic and parasympathetic nerve fibers. There are lymph nodes around the parotid gland and in its thickness (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, diameter (width) - 2-3 mm. In older people it is wider than in children. Usually the excretory duct leaves at the border of the upper and middle third of the gland. The transition from 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 can vary, i.e. it can be straight, arched, curving and very rarely bifurcated. The excretory duct of the parotid gland passes along the outer surface m.
masseter,
bends 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. Structure of the parenchyma of the gland with the presence of an intraglandular lymph node. Microphotograph of parotid gland tissue. Hematoxylin-eosin staining.
Macroscopically, the parotid gland, depending on the blood supply, has a pinkish or yellowish-gray color, a lumpy surface and a moderately dense consistency. In older people, the glands are paler, heavier, and of uneven density.
The main structural units of the parotid gland parenchyma are the alveolar terminal secretory sections (acini), compactly located in lobules and consisting of glandular epithelial cells, with small ducts located between them. The terminal secretory sections are represented by pyramidal cylindrical cells, the wide base of which is adjacent to the basement membrane (Fig. 23.1.2 - 23.1.3). Near the mouth there are goblet cells that secrete mucus, which form a chemical barrier to the upward penetration of microbes 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.
Extensive experimental material provides 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 (on average about 5 ml). 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 secretion, the parotid gland belongs to the purely serous glands.
Submandibular gland (glandula submandibularis) - paired alveolar, in places tubular-alveolar salivary gland, which is located in the submandibular triangle of the neck (Fig. 23.1.4).
Located between the base of the lower jaw and both bellies of the digastric muscle. The upper lateral part of the gland is adjacent to the fossa of the same name (fossa of the submandibular gland) of the lower jaw, reaching its corner from behind, 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 hypoglossus and the anterior belly of the digastric muscle. For a considerable extent of its front part the gland is covered m. mylohyoideus, and behind it bends over its posterior 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, internal view (according to V.P. Vorobyov,
Midline section of the floor of the mouth and mandible; the mucous membrane is removed; gland ducts are highlighted.
1- medial pterygoid muscle; 2-lingual nerve; 3- small sublingual ducts; 4- 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- maxillohyoid muscle; 10- submandibular gland.
Thus, the bed of the submandibular gland is limited: from the inside the diaphragm of the floor of the mouth and the hyoglossus muscle; outside- the inner surface of the body of the lower jaw; from below- the anterior and posterior bellies of the digastric muscle and its intermediate tendon.
The excretory duct of the submandibular gland, as a rule, departs from its superomedial section. Bending over the posterior edge of the mylohyoid muscle, it is located on the lateral side of the mylohyoid muscle, and then passes between it and the mylohyoid muscle. Next it goes between the sublingual gland and the more medially located genioglossus muscle. The excretory duct opens on the mucous membrane of the floor 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 called sublingual caruncle (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 significantly narrower than in the parotid gland (PA. Zedgenidze, 1953; L. Sazama, 1971).
The gland capsule is formed by splitting the superficial layer of the neck's own fascia. The capsule is dense on the outside and thin on the inside. Between the capsule and the gland there is loose fatty tissue, which makes it easy to remove the gland (in the absence of inflammatory changes) from the surrounding soft tissue. Lymph nodes are located in the fascial bed of the gland (section 9.2, volume I of this Manual). The weight of the gland averages from 8 to 10 g, and after 50 years of age the weight of the gland decreases (A.K. Arutyunov, 1956). The consistency of the gland is moderately dense, the color is pinkish-yellow or gray-yellow.
The blood supply to the submandibular gland is provided by the facial, lingual and submental arteries. The facial artery enters the posterior part of the 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 upward and forward, most often located under the gland. Less commonly, it 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 the facial vein.
Lingual nerve, emerging from the gap between the pterygoid muscles, lies directly under the mucous membrane of the floor of the oral cavity 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 hyoglossus muscle. Being on the muscle, the nerve descends down, forming an arch, convex downwards and covered by the gland. In case of chronic inflammatory processes in the submandibular gland, the nerve may be in adhesions and damage may occur during extirpation of the gland.
Facial nerve, or rather its marginal branch, runs approximately 1 cm below the lower edge of the lower jaw. Therefore, an incision in the submandibular region is made 1.5-2 cm below the lower edge of the jaw. It receives secretory iron fibers from the vegetative submandibular ganglion (ganglion).
In healthy people, from 1 to 22 ml of unstimulated saliva are produced within an hour (on average about 12 ml). In the saliva of the submandibular gland, the pH ranges from 6.9 to 7.8 (T.B. Andreeva, 1965).
By the nature of the secretion, the submandibular gland is mixed, i.e. serous-mucous.
The epithelium of the ducts is the same as in the parotid gland, with the only difference that it is often multilayered (P. Rother, 1963). This can explain the significant resistance to contrast pressure (during sialography) or washing fluid (during the treatment of inflammatory diseases of the gland).
Sublingual gland{ g. sublingualis) - The paired tubular-alveolar salivary gland is 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 the inside borders on the hypoglossal and genioglossus muscles (the lingual nerve, the terminal branches of the hypoglossal nerve, the lingual artery and vein, and the excretory duct of the submandibular gland are adjacent to it). From below- located in the space between the mylohyoid and chin-hyoid muscles. Above- mucous membrane of the floor 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 (length 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 has its own separate ducts, which are called small sublingual ducts. The latter open along the sublingual fold at the bottom of the mouth. The bulk of the gland is collected in one common duct, which flows into the excretory duct of the submandibular gland near its mouth. The length of the common excretory duct is from 1 to 2 cm, and the diameter is from 1 to 2 mm. It is extremely rare that the excretory duct of the sublingual gland can open on its own near the mouth of the excretory duct of the submandibular gland. The gland is supplied with blood by the sublingual artery (departs from the lingual artery), venous outflow occurs through the sublingual vein. It receives sympathetic innervation from the autonomic sublingual ganglion. Innervation - from the lingual nerve.
According to the composition of the secretion, the sublingual gland belongs to the mixed serous-mucosal 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 research by W. Pigman (1957), from the major salivary glands, 69% of saliva is secreted by the submandibular glands, 26% by the parotid glands and 5% by the sublingual glands.
The secretion of the minor 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 minor salivary glands is determined in an area of the mucous membrane equal to 4 cm 2. Indicators that occur normally in practically 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, parotin and other chemicals, endocrine factors, enzymes.
In conclusion, I would like to remind you that the names of the ducts of the major salivary glands are also associated with the names of scientists. This is what the duct of the parotid gland is commonly called Stenon's(Stenonii), submandibular - Wharton(Wartonii), main duct of the sublingual gland - Bartalin(Bartalinii), and the small ducts of the sublingual gland - rivinium(Rivini).
Humans have minor and major salivary glands. The group of small glands includes the 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 saliva secreted - mucous, serous or mixed. The large salivary glands are the paired parotid, sublingual and submandibular glands.
Topography of the parotid gland
The parotid glands, the largest of all, produce protein secretions. 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 canal and the membranous part of the temporal bone, the lower edge is located near the angle of the lower jaw. The superficial part of the glands lies under the skin, covers the masticatory muscle and the branch of the lower jaw. Externally, the parotid glands have a dense fibrous capsule fused with the surface layer of the neck's own fascia.The tissue of the organ is represented by glandular lobules with an alveolar structure. The walls of the alveolar vesicles consist of secretory cells. In the layers of fibrous tissue between the lobules there are intercalary ducts. One pole of the secretory cells faces 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 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 1–2 cm below the arch of the zygomatic bone. At the anterior edge of the muscle, it pierces the fat body and the muscle itself, opening on the vestibule of the mouth opposite the 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 retromandibular vein.
Topography of the submandibular gland
The submandibular gland secretes saliva of a mixed protein-mucosal nature. It has a lobular structure. The gland is located in the submandibular fossa, bounded above by the mylohyoid muscle, behind by the posterior belly of the digastric muscle, in front by the anterior belly of this muscle, and externally by the subcutaneous muscle of the neck. The gland is covered with a capsule representing a layer of the neck's own fascia. 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 emerges on its medial surface and lies between the mylohyoid and mylohyoid muscles.Topography of the sublingual gland
The sublingual salivary gland secretes predominantly mucous secretion (mucin) and is formed by lobules with an alveolar structure. The gland is located under the side 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 formed; at the 7th week, the sublingual glands are formed. The secretory sections of the glands are formed from the epithelium, and the connective tissue partitions 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 general name for inflammation of the salivary glands is sialadenitis. Inflammatory diseases in the salivary glands occur when an infection occurs in the blood, lymph, or ascending from the oral cavity. The inflammation process can be serous or purulent.A viral infectious disease of the parotid gland is mumps or mumps. If a child's parotid glands are symmetrically swollen and painful, these are symptoms of mumps. A complication of mumps contracted in childhood is male infertility. The mumps virus damages not only the salivary glands, but also the germ 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 with Sjogren's syndrome ( group of diffuse connective tissue diseases). Sjögren's syndrome is an autoimmune disorder of the exocrine glands, joints and other connective tissue structures. The causes of the disease are considered to be viral infections coupled with genetic predisposition.
Stone sialadenitis is 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 the formation of a retention cyst.
Other reasons for the formation of retention cysts of the salivary glands: trauma, inflammation of the ducts with subsequent blockage and disruption of the outflow of saliva. 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 due to the formation of salivary fistulas, narrowing or fusion of the excretory duct, which leads to stagnation of saliva. Acute organ damage is determined by the following symptoms: the release of saliva from the wound, the formation of a salivary streak - the accumulation of saliva under the skin. Treatment of the consequences of injury to the parotid gland - suturing the wound, surgery to restore the mouth of the duct when it is closed, surgical repair of salivary fistulas.Tumor diseases
True tumors of the salivary glands can develop from the epithelium of the ducts and secretory cells. A benign neoplasm is called an adenoma, a malignant one is called cancer or sarcoma. Tumors of the salivary glands do not hurt in the initial stages. Therefore, 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 is 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:
formation of stones in the salivary ducts;
benign and malignant tumors.
Treatment of cysts and tumors of the salivary glands is removal of the affected organ. The remaining healthy glands produce 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. To obtain information about the location, number and size of stones or tumors, additional studies are required:contrast radiography – sialography;
duct probing;
cytological examination of secretions;
Ultrasound – ultrasound examination;
magnetic resonance or computed tomography;
biopsy to clarify the histological type of tumor.
About transplantation
Scientists have developed an autotransplantation technique—transplanting one of the patient’s own salivary glands under the skin of the temple. The operation allows you to effectively treat 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 obtained 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. Because the optimal treatment for benign salivary gland tumors remains surgical removal, an understanding of salivary gland anatomy is essential to avoid complications.
Salivary glands begin to form at 6-9 weeks of intrauterine life. The major salivary glands originate from the ectoderm; the minor salivary glands can originate from both the ectoderm and the endoderm. Since the capsule around the submandibular salivary gland is formed earlier than around the parotid gland, lymph nodes sometimes migrate into the thickness of the latter. This explains the fact that in the parotid salivary gland, unlike 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, acini are divided into serous, mucous and mixed. From the acini, the secretion 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 predominantly serous secretion, sublingual and minor salivary glands - mucinous, submandibular gland - mixed.
Although actually parotid gland It is represented by only one lobe, but from a surgical point of view it is divided into a superficial lobe, located lateral to the facial nerve, and a deep lobe, located medial to the facial nerve. 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 passes below and deeper from the gland, the facial artery and vein are higher and deeper.
After leaving the cranial cavity preganglionic fibers separated from the glossopharyngeal nerve, forming the tympanic nerve and again entering the cavity through the inferior tympanic canaliculus. In the middle ear cavity they pass over the promontory of the cochlea, and then leave the temporal bone as the lesser petrosal nerve. The lesser petrosal nerve leaves the cranial cavity through the foramen rotundum, where its preganglionic fibers then form synapses with the auricular ganglion. Postganglionic fibers in the auriculotemporal nerve innervate the parotid salivary gland.
Excretory duct of the parotid gland is called Stensen's duct. It runs in a horizontal plane approximately 1 cm below the zygomatic bone, often in close proximity to the buccal branch of the facial nerve. Anterior to the masticatory 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 external carotid artery system, and venous outflow occurs 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 shape of a wedge, bounded above by the zygomatic bone; anteriorly by the masseter muscle, lateral pterygoid muscle and ramus of the mandible; below by the sternocleidomastoid muscle and the posterior belly of the digastric muscle. The deep lobe lies lateral to the peripharyngeal 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 located facial, auriculotemporal and greater auricular nerves; 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 auricular 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 is divided into the temporal and zygomatic nerves, and the lower 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 is divided 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 (ptialin, 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
The parotid salivary gland (gl. parotis) is a pair, 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 the 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, at the bottom it is at the level angle of the lower jaw (Fig. 224). The superficial part of the gland is located under the skin, covering m. masseter and ramus of the mandible. The gland is covered with a dense connective tissue capsule, which connects to the superficial layer 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. Excretory ducts pass between the lobules in layers of connective tissue. Secretory cells have 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 to not only the terminal pressure vis a tergo, but also the contraction of myoepithelial cells in the terminal sections of the gland.
Gland ducts. Intercalary ducts are located in alveoli formed by secretory cells. The striated ducts are larger, lined with single-layer columnar 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 merging all interlobular ducts, is located 1-2 cm below the zygomatic arch, on the surface of the masticatory muscle. At its anterior edge, it pierces the fatty body and buccal muscle, and opens into the vestibule 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 retromandibular 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 - chapter. labiales; 3 - labium superius; 4 - lingua; 5 - gl. lingualis anterior; 6 - labium inferius; 7 - caruncula sublingualis; 8 - ductus sublingulis major; 9 - mandibula; 10 - m. genioglossus; 11 - m. digastricus; 12 - chapter. sublingualis; 13 - m. mylohyoideus; 14 - ductus submandibularis; 15 - chapter submandibularis; 16 - m. stylohyoideus; 17 - m. digastricus; 18 - m. masseter; 19 - chapter. parotis 20 - f. masseterica et fascia parotidea; 21 - ductus parotideus; 22 - chapter. parotis accessoria.
Submandibular gland
The submandibular gland (gl. submandibularis) has a lobular structure and produces a protein-mucus secretion. The gland is localized under the edge of the lower jaw in the regio submandibularis, which is limited above by m. mylohyoideus, behind - the posterior belly of the digastric muscle, in front - its anterior belly, 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 emerges 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 mucous secretion (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.
X-rays of the salivary glands
After introducing a contrast agent into the duct of any salivary gland (sialography), the contour and architecture of the ducts can be used to judge the condition 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, the ducts of the 5th, 4th, 3rd, 2nd and 1st order, which have a tree-like shape, are easily filled (Fig. 225). All ducts are cleared of the contrast agent within the first hour after administration.
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 in the 6th week of the intrauterine period, and the sublingual gland - in the 7th week. The terminal sections of the glands are formed from epithelium, and the connective tissue stroma, dividing the gland rudiment into lobes, is from mesenchyme.
Phylogeny of the salivary glands
Fish and aquatic amphibians do not have salivary glands. They appear only in terrestrial animals. Land 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 masticatory muscle, and their ducts are connected to the canal or groove of the front teeth. When the masticatory muscle contracts, the venom of the gland is squeezed 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
DUCT OF STENON- (Stensen's duct) excretory duct of the parotid salivary gland... Explanatory dictionary of medicine
This name refers to the very diverse glandular appendages of the oral cavity and pharynx. Thus, in worms, various unicellular glands, called S., pharyngeal and septal, open into the pharynx. Then they have a peculiar function...
V. M. Sh. The S. glands (gl. Salivales) include three pairs of glands: the parotid gland, the submandibular gland and the sublingual gland, 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 the Bisha 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 floor of the mouth and tongue, and on the sides by the cheeks. The oral cavity opens... ... 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 previously existed. Pathological anatomy.... ...
- (galandulae oris) There are small and large salivary glands (Fig. 1). Malye S. zh. (labial, buccal, molar, lingual and palatal) are located in the oral mucosa. By the nature of the secretion secreted, small S. divided into serous, ... ... Medical encyclopedia
PAROTICAL GLAND- (glandula parotis), 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 retropubinal fossa (fossa he tromandibularis). The shape of the gland is completely adapted to the walls of this... Great Medical Encyclopedia
