Salivary Glands PDF

Salivary gland- Introduction Dr Sandeep Gupta Oral Biology  GLAND A gland is a structure that produces a chemical secretion necessary for normal body functioning. 2  Classification OF GLAND  According to d...

Salivary gland- Introduction Dr Sandeep Gupta Oral Biology  GLAND A gland is a structure that produces a chemical secretion necessary for normal body functioning. 2  Classification OF GLAND  According to distribution Endocrine Exocrine  According to Branching of duct Simple Compound  According to Secretion Apocrine Holocrine Merocrine Eccrine 3  Secretory units Tubular Alveolar or Acinar Tubulo alveolar or Tubuloacinar Acc. to structures Unicellular - eg – goblet cells Multicellular 4 5  SALIVARY GLAND Salivary glands are compound, tubuloacinar, merocrine, exocrine glands whose ducts open into the oral cavity. 6  2 components 1.Parenchyme 2.Mesenchyme Oral epithelium Parenchymal elements Secretory units 7  Mesenchymal elements Capsule around the gland and extends into it divides secretory units and ducts into lobes and lobules. The blood and lymph vessels and nerve that supply the gland are contained with in the connective tissue 8  CLASSIFICATION: A. According to size I. Major: Parotid, Submandibular, Sublingual II. Minor: Glands of lips, cheeks, hard & soft palate. B. According to secretion:  Purely serous: Adult parotid, von ebner gland  Purely mucous: Palatine, glossopalatin, weber glands and minor sublingual glands  Mixed glands: submandibular, sublingual, buccal, labial and blandin nuhn glands 9 Numerous smaller minor glands are located in oral cavity- The lingual The labial The palatal The buccal Glossopalatine Retromolar 10 DEVELOPMENT 11  Stages in the development of salivary glands: i. Formation of bud. ii. Formation of chord. iii. Branching of chords. iv. Formation of lobule. v. Canalization of chords. vi. Cytodifferentiation. 12  Development of Salivary glands Stage I (Bud Formation) The underlying mesenchyma induces the overlying epithelium to proliferate. The epithelium thus forms a bud. A mesenchymal condensation is seen below the bud. A thin layer of basal lamina seperates the bud from the underlying mesenchyme. 13  Stage II (Formation Of Chord) The epithelial bud proliferates to form a solid chord of cells. The underlying mesenchmal condensation also proliferates. Stalk elongationFGF7. 14  Stage III (Branching of Epithelial Chord) The epithelial chord proliferates and its ends branch into bulbs. This stage denotes the initiation of the branching. Branching process  Regulated by EGF( epidermal growth factor) & its receptors( α6 integrin). 15 Intiatation of branching 16  Stage IV (Lobule Formation) The terminal ends branch extensively forming numerous bulbs. The connective tissue below the epithelial chord forms a capsule and surrounds the entire glandular structure. 17  Stage V (Canalization) The chords form a central tube or duct. Occur due to different rates of cell proliferation between the outer and inner layers of the epithelial chord. Fluid secretion by the duct cells which increases the hydrostatic pressure within to form a canal. 18 Canalization 19 State VI (Cytodifferentiation) The terminal secretary acini and intercalated ducts differentiate to form the terminal ends of the branching tree. Induction of acinar cell differentiation Interaction b/w laminin & syndecan. 20 Cytodifferentiation 21 6th-8th week Major Salivary gland begin as epithelial buds Early 6th week Appearance of buds of Parotid Gland near the angle of primitive mouth. 8th week Appearance of buds in the sulcus surrounding the sublingual fold in the floor of primitive mouth 10th week Cords are canalized & form ducts 12th week Canalization of cords of submandibular gland & development of acini. Minor salivary glands start developing. 18th week Beginning of secretion from parotid gland. 24th- 35th week Myoepithelial cells become active. 22  Salivary Glands In human beings-3 pairs of major salivary glands are present. They are: I. The Parotid gland II. The Submandibular gland III. The Sublingual gland 23  PAROTID GLAND It is the largest salivary gland. Anatomical Location: It is situated below the external acoustic meatus b/w the ramus of the mandible & sternocleidomastoid. Anteriorly , the gland overlaps masseter muscle. It resembles a three sided pyramid & has 4 surfaces and 3 boarders. 24 25 26 Weight: 15 gms Parotid duct :( stenson’s duct) Thick walled & 5 cms long. opens into the vestibule of the mouth opposite the crown of the upper 2nd molar tooth. Blood Supply: External Carotid artery External jugular vein Nerve Supply: auriculotemporal nerve 27 Lymphatic drainage: Parotid nodes Upper deep cervical nodes 28  Clinical Consideration: Mumps It is an infectious disease of the salivary glands caused by specific virus Parotid Abscess: It may be caused by spread of infection from the mouth or due to suppuration of parotid gland. Facial nerve damage ; operation 29  SUBMANDIBULAR GLAND It is large, well-encapsulated salivary gland 3 cm in diameter- about the size of walnut Roughly J-shaped- surrounded by posterior border of the mylohyoid; dividing it into a large superficial part & a small deep part. 30  SUBMANDIBULAR GLAND Anatomical Location: Located in the submandibular triangle behind the free border of the mylohyoid muscle. Superficial part: Fills the digastric triangle Deep part: Lies deep to mylohyoid Weight:10-15 gms Name of Duct - Wharton’s Duct Thin walled & about 5 cms long Opens in the floor of the mouth on the summit of sublingual papilla. 31  SUBMANDIBULAR GLAND Blood Supply: Facial artery Common facial or lingual vein Lymphatic Supply: Submandibular lymph nodes Nerve Supply: Sensory fibers from lingual nerve 32  SUBLINGUAL SALIVARY GLAND It is smallest of three salivary glands It is almond- shaped Weight: 3-4 gms Anatomical Location: It lies above mylohyoid below the mucosa of floor of mouth Medial to sublingual fossa of the mandible Lateral to the genioglossus. 33  SUBLINGUAL SALIVARY GLAND Sublingual ducts: (ducts of rivinus)  It has 8-20 excretory ducts  Smaller sublingual ducts open into the floor  of mouth on the summit of sublingual fold  Few of them join the submandibular duct. Blood Supply: Lingual & submental arteries Nerve Supply: Similar to Submand. gland 34 Clinical Consideration: If the ducts draining any salivary gland become obstructed, the gland is at risk of developing a retention cyst. Mostly seen in the minor salivary glands which line the lips & the oral cavity. 35  Clinical Consideration: Ranula: When trauma occurs in the floor of mouth & obstructs the draining duct/ducts of the sublingual gland, the retention cyst is called ranula Thank You