ANATOMY AND PHYSIOLOGY OF SALIVARY GLANDS 12.05.pptx

anatomy and physiology of salivary glands

1. ANATOMY AND PHYSIOLOGY OF SALIVARY GLANDS Dr. Sudi n Kayastha Resident ORL and HNS Bir Hospital,NAMS

2. ANATOMY 3 major salivary glands: parotid glands submandibular glands sublingual glands Many minor salivary glands (600-1000 ) : in mucosa of cheeks, lips, palate.

3. Development of Salivary G lands Interaction of epithelium with underlying mesenchyme Glandular tissue develop as an outgrowth of buccal epithelium that invades the underlying mesenchyme This outgrowth is ectodermal in parotid gland and minor salivary gland and endodermal in submandibular and sublingual glands.

4. Parotid glands : originate from the corner of stomodeum during 6 th week of intrauterine life. Submandibular glands arise from floor of mouth at end of 6 th week Sublingual glands develop lateral to submandibular primodium at the 8 th week. Minor salivary glands don’t develop until 12 th week of gestation.

5. Developmental stages

6. MICROSCOPIC ANATOMY Basic structural unit : ACINI

7. Serous Acini Pyramidal in shape Rounded nucleus Nucloeli ; centrally placed Cytoplasm : granular Secretions : proteinous in nature Rich in zymogen granules

8. Mucous acini Cells : tall with flat nuclei at bases Lumen larger than that of serous acini Secretions : mucopolysaccharide

9. Mixed acini Contain both serous and mucous elements

10. Intercalated ducts : low cuboidal cells Rich in carbonic anhydrase Thus cells secrete bicarbonate into lumen and absorb chloride from lumen Secrete lysozyme and lactoferrin

11. Striated ducts : Lined by simple cuboidal cells Cells absorb sodium from lumen and secrete potassium into the lumen Hypotonic fluid.

12. Excretory ducts Pseudostratified columnar epithelium No modification of saliva

13. Parotid Gland Largest salivary gland Mostly serous Weight : 25 gm Irregularly lobulated Wedge shaped

14. Accessory parotid gland pars accessoria separate part of the gland lying on the masseter parotid duct below and the arch of the zygoma above

15. Extensions LATERAL zygomatic arch superiorly upper part of the neck inferiorly ANTERIOR masseter muscle POSTERIOR external auditory canal mastoid process overlying the lateral process of C1 . MEDIAL: Fills the gap between mandible anteriorly and mastoid and the styloid process posteriorly . It extends close to lateral wall of the oropharynx

16. Surfaces and Borders

17. The Capsule Derived from Deep cervical fascia Largely tough and inelastic but thins in anterior and in apex Deep lobe tumours limited by stylomandibular ligament and expads into parapharyngeal space

18. Structures within parotid gland Arteries: maxillary artery superficial temporal artery Vein: Retromandibular vein useful radiological landmark for the nerve . Nerve: Facial nerve

19. F acial N erve Enter from posteromedial surface of the gland Divides the gland into superficial and deep lobes comprising approximately 80% and 20% of the gland respectively Divides into two main temporal and cervical divisions. Further subdivisions then occur to form five branches – temporal, zygomatic , buccal , mandibular and cervical

20. Branching pattern is variable and a number of classifications have been described. McCormack et al. and Daviset al. both described six patterns. Katz and Catalano described five patterns Kwak et al described four patterns based on the :origin of the buccal branch. : crossinnervation between branches

21. Katz and Catalano classification:

22. P arotid duct Stensen lined by low cuboidal epithelium originates within the deep lobe of the gland only small ductules connect the superficial lobe with the duct. measures approximately 5 cm in length internal calibre : 0.6 mm.

23. course

24. Nerve supply

25. Blood supply Arterial supply : Branches of external carotid artery Venous drainage : external jugular vein and internal jugular vein

26. Submandibular gland second largest of the major salivary glands. consist of a larger superficial part and a smaller deep part gland lies in the submandibular triangle

27. SUBMANDIBULAR TRIANGLE anterior belly of the digastric muscle posterior belly of the digastric muscle inferior margin of the mandible.

28. Submandibular gland Irregular in shape Weighs 7–16 gm SUPERFICIAL SURFACE Skin Platysma and Fibrous capsule: derived from the deep cervical fascia. Fascia is crossed by: facial vein Cervical branch of facial nerve Marginal mandibular nerve .

29. MEDIAL SURFACE lies on surface of mylohyoid Anteriorly related :nerve to mylohyoid : submental vessels . Posteriorly : overlies hyoglossus , lingual nerve, with its submandibular ganglion, hypoglossal nerve, stylohyoid and posterior belly of digastric

30. LATERAL SURFACE : lies adjacent to the body of the mandible in the mandibular fossa and the origin of the medial pterygoid . INFERIOR SURFACE : skin, platysma deep cervical fascia related to the cervical branch of the facial nerve.

31. DEEP PART of the gland lies within the floor of the mouth, between mylohyoid and hyoglossus L ies between the lingual nerve above and the hypoglossal nerve below.

32. S ubmandibular duct 5cm long. Formed by the coalescence of numerous ducts within the superficial part of the gland Emerges from the medial surface of the gland Narrowest at the ostium . Mean duct diameters 1.5 mm and 0.5 mm. COURSE: Traverses the deep part of gland Runs anteriorly along the floor of the mouth between mylohyoid and hyoglossus Emerges on the summit of the sublingual papilla adjacent to the lingual frenulum

33. BLOOD SUPPLY blood supply : facial and lingual arteries venous drainage : corresponding facial veins . LYMPHATIC DRAINAGE deep cervical and jugular chains of nodes .

34. Nerve supply

35. Sublingual gland Smallest of the paired salivary glands Almond-shaped Weighs approximately 4 gm lie beneath the mucosa of the floor of the mouth, between the mandible and genioglossus muscle Inferiorly bounded by : mylohyoid

36. The submandibular duct (Wharton’s) and the lingual nerve pass between the sublingual gland and genioglossus muscle . No dominant duct drainage Ducts of R ivinus open directly into the summit of sublingual fold but some may open into submandibular dut itself

37. Vessels and nerves Blood supply : lingual and submental arteries Lymphatic drainage : submandibular nodes Nerve supply : similar to submandibular glands

38. Physiology of salivary gland Phases of salivary secretion: Primary phase: Active process Saliva produced by acinar cells Similar to plasma in osmolarity and concerntration Modification of saliva Takes place as saliva passes to ductal system. Saliva becomes more hypotonic

39. Composition of saliva

40. F unctions of saliva

41. Salivary flow Average volume: 1-1.5 L per 24 hr Basal salivary flow rate : 0.001-0.2 ml/min/gland Stimulated salivary rate : 0.18-1.7 ml/min/gland pH: 5.6-7

42. Unstimulated state Submandibular:69% Parotid:26% Sublingual:5% Stimulated state Submandibular:26% Parotid:69% Sublingual:5%

43. Autonomic stimulation of secretion PARASYMPATHETIC NERVOUS SYSTEM

44. Parasympathetic system increases the salivary secretion :

45. Sympathetic nervous system Acts intermittently Can increase salivary secretion but less than parasympathetic nervous system Mainly modifies the compostion of saliva

46. Mechanism of salivary secretion Parasympathetic system Sympathetic system

47. parasympathetic

48. Sympathetic system

49. MECHANISMS OF ION TRANSPORT IN SALIVARY ACINI

50. FACTORS AFFECTING SALIVARY FLOW 1. drugs are the most common cause of measurable decreased salivary gland function

51. FACTORS AFFECTING SALIVARY FLOW 2.Depression and anxiety states 3.Postmenopausal state 4.Old age 5.Dehydration induced by, haemorrhage , diarrhoea,chronic vomiting, polyuria secondary to diabetes and restricted fluid intake or overdose of diuretics

52. COLLECTION OF SALIVA Facilitates a diagnosis of xerostomia Collection of saliva is performed under three circumstances: • Unstimulated flow of total saliva • Stimulated flow of total saliva • Stimulated or unstimulated flow of an individual gland

53. Salivary stimuli The purpose of this manoeuvre is to flush out stagnant secretions that confuse the analysis . systemic sialagogue : pilocarpine can alter the concentrations of normal constituents,particularly sodium and potassium Can also cause systemic cholinergic effects such as colic,diarrhoea , bradycardia and sweating.

54. Salivary stimuli Local sialagogue : 5 percent citric acid solution Does not interfere with the composition of the final specimen. Five drops of this solution can be dropped from a pipette or disposable syringe onto the dorsum of the tongue

55. Collection of mixed whole saliva methods for collecting saliva spitting drainage suction cotton wool rolls.

56. SPITTING AND DRAINAGE METHODS: comfortable sitting position with the head inclined forward encouraged to spit at on one minute intervals or to allow saliva to drain out of the mouth into a funnel draining into a sterile collecting vessel

57. SUCTION Requires the equipment associated with a dental chair. Patient is put into a similar position as before to allow saliva to collect into the anterior floor of the mouth. A saliva ejector is placed behind the lower incisor teeth and the secretion is trapped in a bottle intervening between the ejector and the drainage system

58. ABSORBENT DEVICES: Preweighed cotton wool rolls are placed under the tongue for a two-minute period then taken out and reweighed. quantitation only. OraSures : simplify saliva collection and preserve it for analysis. OraSure is a cotton- fibre pad which can absorb 1 mL of oral fluid.

59. Collection of parotid gland saliva cannulating the parotid duct with a polythene catheter or using a suction cup . For suction,the most widely used devices are the Carlson–Crittenden cups.

60. submandibular and sublingual glands is typically collected using a syringe

61. SIALOCHEMISTRY

62. SIALOCHEMISTRY Factors affecting composition of saliva

63. SIALOCHEMISTRY Composition of saliva can change in diseased state particularly by those which can cause xerostomia

64. SIALOCHEMISTRY

65. Antibacterial substances in saliva Lysozyme Lactoferrrin Buffering capacity pH Immunoglobulins Flow rate

66. SALIVARY ASSAYS IN DIAGNOSIS Saliva is a medium for many diagnostic assays. Malignancy screening Hormone monitoring Drug monitoring Microbial antigens and antibodies screening Monitoring of immunization status

67. Malignancy screening Oral squamous cell carcinoma : p53 : defensin-1 Breast carcinoma : c-erbB-2 :cancer antigen 15-3 (CA15-3)

68. Hormone monitoring Testestorone levels Progesterone levels

69. Drug monitoring Drugs that are not ionizable or not ionized within the pH range of saliva are most suited to salivary monitoring . If a constant saliva/plasma ratio can be established Used for detection of abuse

70. Microbial antigens and antibodies VIRAL HEPATITIS: hepatitis B antigen HIV HPV DNA

71. MONITORING OF IMMUNIZATION STATUS Measles,mumps and rubella immunization status

72. References: Scott brown 8 th edition, volume 3 Scott brown 7 th edition, volume 3 Cummings ORL HNS 6th Edition BD Chaurasia’s Human anatomy Moore’s clinically oriented anatomy,7 th edition Ganong’s review of medical physiology:25 th edition Guyton and Hall Textbook of Medical Physiology 13 th edition

73. thank you