Salivary Glands PDF

Salivary Glands [Oral and Dental Sciences] Miss H Rogers GDC ILOs ▪ 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their application to patient management ▪ 1.1.6 Describe relevant and appropriate physiology and explain its application to...

Salivary Glands [Oral and Dental Sciences] Miss H Rogers GDC ILOs ▪ 1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their application to patient management ▪ 1.1.6 Describe relevant and appropriate physiology and explain its application to patient management Related topics: ▪ Embryology ▪ Saliva & Salivation ▪ Xerostomia ▪ Skull ▪ Regional anatomy ▪ Extra-oral examination Aim To gain an overview of the salivary glands including their positioning, histology and function Learning Outcomes By the end of this lecture you should be able to: 1. List the major salivary glands 2. Describe the each salivary glands’ positioning, associated duct, saliva production and innervation 3. Describe the histological structure of a salivary gland 4. Outline the disorders that may affect salivary glands 3 Formation of Salivary Glands Covered in BMS lecture: ‘Embryology of the head, face and oral cavity’ 4 Types of salivary glands There are three bilateral pairs of major salivary glands: ▪ Parotid glands ▪ Submandibular glands ▪ Sublingual glands …and numerous minor salivary glands The major salivary glands produce 90% of the total salivary volume 5 Major Salivary Glands 6 Parotid ▪ Largest of the major glands ▪ 100% serous saliva ▪ 25% of total saliva volume Position ▪ Below the external auditory meatus ▪ Between the mastoid process and the posterior border of the ramus 7 Duct ▪ Stensen’s or Parotid Duct ▪ 5cm long ▪ Runs from the gland outside the masseter muscle parallel to, and 1cm below, the zygomatic arch. ▪ Pierces the buccinator muscle opening into the oral cavity via the Stensen’s papillae. Nerve Innervation ▪ Glossopharyngeal (autonomic) Stensen’s Papillae ▪ Auriculotemporal (sensory) ▪ Intimately associated with the Facial nerve 8 Submandibular ▪ Mixed saliva secretions ▪ Half the size of the parotid gland (walnut size) ▪ 60-65% of total saliva volume Position ▪ Between the body of the mandible and the mylohyoid muscle, in the submandibular fossa 9  Duct ▪ Wharton’s duct ▪ 5cm long ▪ Opens under the anterior part of the tongue, lateral to the lingual fraenum at the sublingual caruncle Nerve Innervation ▪ Chorda tympani ▪ Lingual branch of the inferior dental nerve 10 Sublingual ▪ 60% mucous saliva ▪ Smallest of the major salivary glands (almond size) ▪ 5-10% of total saliva volume Position ▪ Floor of the mouth in the sublingual fossa 11  Duct ▪ Bartholin’s duct ▪ 10-20 smaller ducts (Rivinus ducts) open along the sublingual fold Nerve Innervation ▪ Same as the submandibular gland 12 13 New Discovery! The Tubarial Glands Located in the nasopharynx. Literature suggests that it may contain a large number of seromucous acini, playing a role in nasopharynx/oropharynx lubrication and swallowing. 14 Minor Salivary Glands 15  Mixed saliva, predominately mucous Produce lots of salivary proteins >10% of the total saliva volume Named according to where they are found e.g. buccal or labial salivary glands To read more on the individual minor salivary glands, have a look at Section 2 in Gupta, S. & Ahuja,N. (2019) Salivary Glands. 16 Salivary Gland Structure 17 Epithelium- lines the ducts and produces the saliva. Connective tissue- surrounds the epithelium, protecting and supporting the gland. The connective tissue is divided into: the capsule (which surrounds the entire outer portion of the gland) the septum [plural, septa] (which divides the inner portion of the gland into lobes and smaller lobules). The capsule and septa carry the nerve and blood supply to the cells. 18 Adenomeres An adenomere is the working part of a salivary gland and is surrounded by connective tissue 19 Acini Within the adenomere are secretory units (acini) which are made up of secretory cells. Their base is resting against the surrounding connective tissue (supplying nerves and blood to the cells). The acini are classified into: ▪ Mucous acini ▪ Serous acini …or a mixture of both! 20  Serous Acini: ▪ Serous secretory cells ▪ Produce a watery serous secretion (serous saliva) ▪ Functions of serous saliva include: ▪ Lubricating food ▪ Enzymic action begins digestion ▪ Removing epithelial debris ▪ Diluting food 21 Mucous Acini: ▪ Mucous secretory cells ▪ Have a wider lumen ▪ Produce a viscous mucin rich secretion (mucous saliva) ▪ Functions of mucous saliva include: ▪ Binding food into a bolus ▪ Protect the oral cavity against frictional abrasion ▪ Lubrication 22  Serous-mucous Acini: ▪ In a mixed serous- mucous acini the serous secretory cell forms a serous demilune around mucous secretory cell 23  Myoepithelial Cells These cells embrace the acini secretory cells, contracting and squeezing, forcing the saliva out of the lumen and into the ducts 24 Acinar Fluid (not saliva just yet!) Consists of: Water Inorganic Ions Small molecules and products synthesised by cells (mucoproteins and amylase) 25  Ducts Following the secretory end piece are ducts along which the saliva travels and becomes further modified via resorption. There are three types of duct: ▪ Intercalated ▪ Striated ▪ Excretory 26 Intercalated Lined by a single layer of cuboidal epithelial cells Striated ▪ This makes up the bulk of the duct system. ▪ Lined with a single layer of columnar epithelial cells characterised by basal striations ▪ This aids in the modification of the saliva 27 Excretory (terminal) ▪ Or the secretory duct ▪ Saliva exits into the oral cavity via this duct ▪ Lined by pseudostratified columnar epithelium which then changes to stratified cuboidal and then finally stratified squamous epithelium at its opening 28 Supporting Images 29 Blood Supply Supplied by the external carotid artery (plus facial and lingual artery), with vessels (and nerves) entering the gland at the hilum There are two capillary networks, one for the secretory end piece and one for the ducts Control of salivation Salivary nuclei in the brain are stimulated by taste, smells, thoughts etc These trigger neurotransmitter release from nerve endings of salivary glands Click here for an interactive microscopic image of salivary gland tissue. 30 Disorders of the Salivary Glands 31 Hyposalivation Can be caused by: Medications or tablets Radiotherapy Autoimmune diseases Diabetes Salivary stones (can cause severe pain when eating) Which of these cause reversible and which cause irreversible effects? The Cracker Challenge- how it feels to have a dry mouth 32 Obstruction Caniculi Calcium deposits formation in the ducts. Common in the submandibular glands, it can lead to infection or inflammation of the gland Cysts Trauma to the salivary gland or duct causing an accumulation of saliva in the surrounding tissue. ▪ Mucocele- minor glands ▪ Ranula- major glands in the floor of the mouth (could be submandibular or sublingual) 33  Irradiation Head and neck irradiation destroys the secretory cells (atrophy) and leads to xerostomia. Further reading on oral care following radiotherapy: ▪ Devi, S., and Singh, N. (2014) Dental care during and after radiotherapy in head and neck cancer ▪ Cancer Research UK ▪ Mouth Care Foundation 34 Degenerative Sjögren’s syndrome, an immunological disorder that causes: The Body Oral cavity Dry eyes Mild erythema and thinning of the mucosa Acini destroyed Change in lachrymal Erythema, fissuring, coating apparatus and depapillation of the dorsum of the tongue Rheumatoid arthritis is often Traumatic erosions and associated ulcers, angular chelitis and Raynaud phenomenon chapped lips Frothy, ropey and thickened saliva For more information, click here 35 Inflammation/Infection Mumps An acute viral infection causing inflammation and painful swelling of the parotid glands For more information on mumps, click here Nicotine Stomatitis Caused by inflammation of the minor salivary glands located on the palate in response to heat from tobacco use. The duct openings become dilated and can appear as red dots. 36 Sialosis A painless swelling of the parotid glands, not caused by inflammation or infection. Can occur on its own but may also appear as a result of other medical conditions, examples include: Liver cirrhosis Bulimia Diabetes Pregnancy Obesity Kidney failure For more information: The British & Irish Society for Oral Medicine 37 Neoplasms (tumours) These can be: Benign Malignant E.g. Warthin’s tumour E.g. Salivary gland carcinoma Bilateral Warthin’s Click here to tumour- click here read the case to read the case study study Pleomorphic adenoma Acinic cell carcinoma Click here to Click here to read the case read the case study study 38 Functional Disorders Dry mouth caused by: ▪ Emotional disturbances e.g. anxiety ▪ Mouth breathing ▪ Smoking ▪ Drugs Can you name any medications that contribute to dry mouth? 39 Summary With so many conditions potentially impacting on the salivary glands, it is important that they are included on our extra-oral examination. Activity: Complete Salivary gland Position the table below, Duct or create % of total your Innervation saliva volume own, detailing each of the salivary glands covered in this lecture: 40 Additional Resources Journal Article Contreras-Aguilar M.D. & Gómez-García F. (2020) ‘Salivary Glands’ Anatomy and Physiology’, in Tvarijonaviciute A., Martínez-Subiela S., López-Jornet P., Lamy E. (ed.) Saliva in Health and Disease. Springer, Cham. https://doi.org/10.1007/978-3-030-37681-9_1 Online Book Gupta, S. & Ahuja, N. (2019). ‘Salivary Glands’, in Heinbockel, T. & Shields, V. (ed.) Histology. IntechOpen. DOI:10.5772/intechopen.81213. YouTube Ninja Nerd Lecture- Gastrointestinal | Salivation: Parotid, Submandibular, & Sublingual Glands https://www.youtube.com/watch?v=3tasuHt6jKg ▪ Sam Webster- Salivary glands (anatomy) https://youtu.be/gdq8mjsWRkk Other Some good diagrams and images https://www.slideshare.net/upamasishan/salivary-glands-51253694 41 References Bath-Balogh, M., and Fehrenbach, M.J,. (2006) Dental embryology, histology, and anatomy. 2nd Ed. Elsevier. Waugh, A., and Grant, A. (2006) Anatomy and physiology in health and illness. 10th Ed. Elsevier. 42 Any Questions? Email [email protected] 43