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Anatomy of salivary glands

Anatomy of salivary glands. Contributed By :- Dr. Nafisa P arveen Jawahar Lal Nehru M edical C ollege Aligarh M uslim U niversity , I ndia To download more ppts or to upload your ppts , visit www.nayyarENT.com. Embryology.

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Anatomy of salivary glands

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  1. Anatomy of salivary glands Contributed By :- Dr. NafisaParveen JawaharLal Nehru Medical College Aligarh Muslim University, India To download more ppts or to upload your ppts, visit www.nayyarENT.com www.nayyarENT.com

  2. Embryology • The parotid glands are the first to develop in the 4th week of embryogenesis, followed by the submandibular glands at 6th weeks and finally the sublingual glands at 8th weeks. • Parenchymal tissue (secretory) of the glands arises from the proliferation of oral epithelium. www.nayyarENT.com

  3. Embryology • The stroma (capsule and septae) of the glands originates from mesenchyme that may be mesodermal or neural crest in origin. www.nayyarENT.com

  4. Parotid development • Although the parotid anlagen are the first to develop, they become encapsulated after the SMG and SLG. • This delayed encapsulation is critical because after the encapsulation of the SMG and SLG but bafore encapsulation of the parotid, the lymphatic system develops. www.nayyarENT.com

  5. Parotid development • Therefore, there are intraglandular lymph nodes and lymphatic channels entrapped within the parotid gland (PG). • PG is also unique because its epithelial buds grow, branch and extend around the divisions of the facial nerve. www.nayyarENT.com

  6. Embryology • The epithelial buds of each gland enlarge, elongate and branch initially forming solid structures. • Branching of the glandular mass produces arborization. • Each branch terminates in one or two solid end bulbs. www.nayyarENT.com

  7. Embryology • Elongation of the end bulb follows and lumina appears in their centers, transforming the end bulbs into terminal tubules. • These tubules join the canalizing ducts to the peripheral acini. www.nayyarENT.com

  8. Duct Canalization • Canalization results from mitotic activity of the outer layers of the cord outpacing that of the inner cell layers • Canalization is complete by 6th month post conception. www.nayyarENT.com

  9. Acinar cells • At around the 7-8th month in utero, secretory cells (acini) begin to develop around the ductal system. www.nayyarENT.com

  10. Acinar cells of Salivary Glands Classified as : • Serous cells: containing small granules. secrete salivary proteins and enzymes. thin watery secretion. • Mucous cells: contain larger granules, producing mucoproteins. more viscous secretion. • Seromucinous cells: have an intermediate structure. www.nayyarENT.com

  11. Salivary gland secretory unit • Composed of terminal acini • Intercalated, striated and excretory ducts • Myoepithelial cells www.nayyarENT.com

  12. Salivary gland secretory unit • Basic secretory unit is the acinous. • Arranged in a sphere surrounding a duct. • The secretory cells are pyramidal with narrow luminal apices. • Their broader bases rest on a basement membrane surrounded by stellate contractile myoepithelial cells. www.nayyarENT.com

  13. Salivary gland secretory unit • The acinar ducts coalesce into intercalated ducts ,subsequently striated ducts composed of columnar cells, then united into the main excretory duct of the gland. www.nayyarENT.com

  14. Salivary gland secretory unit • The acini in major salivary glands are arranged into lobules and lobes within the glands. • Each lobule has a single excretory duct. • The lobules are linked by dense fibrous tissue containing excretory ducts, vessels , lymphatics , nerve fibres and ganglia to form lobes. www.nayyarENT.com

  15. Major glands/Secretions • Major SG are paired structures and include the parotid, submandibular and sublingual • Parotid: serous • Submandibular: mucous & serous • Sublingual: mucous www.nayyarENT.com

  16. Parotid gland • Largest of the salivary glands. • They resemble a three-sided pyramid. • Wedge shaped in coronal section. • Enveloped by the investing layer of deep cervical fascia. • Each gland has an average weight of 25g. www.nayyarENT.com

  17. Anatomy: Parotid Gland • Nearly 80% of the parotid gland (PG) is found below the level of the external auditory canal, between the mandible anteriorly and the SCM posteriorly. • Superficial to the posterior aspect of the masseter mm www.nayyarENT.com

  18. Anatomy:Parotid Gland • Extensions of PG project to mastoid process • Down the anterior aspect of the SCM for a short distance • Around the posterior border of the mandible. • Superiorly to the to inferior margin of the zygomatic arch www.nayyarENT.com

  19. Parotid gland • The parotid gland is irregularly lobulated. • The superficial surface is concave. • Covered by the superficial fascia, the posterior border of platysma and skin. • Superficial parotid lymph nodes and facial branches of the great auricular nerve overlie this surface. • The great auricular nerve is derived from the cervical plexus ,provides sensory sensation for the lower 2/3rd of the pinna. www.nayyarENT.com

  20. Parotid gland • The superior surface is concave. • Lies adjacent to the cartilaginous EAC and the TMJ. • The auriculotemporal nerve lies in the capsule adjacent to the neck of the mandible. • The apex of the gland lies on the posterior belly of the digastric muscle. www.nayyarENT.com

  21. Parotid gland • The anteromedial surface lies on the posterior border of the ascending ramus of the mandible and the medial pterygoid muscle. • The facial nerve enters the gland on this surface. www.nayyarENT.com

  22. Parotid gland • Posteromedial surface is indented by the external carotid artery before it penetrates this surface of the gland. • It lies on the mastoid process,the posterior belly of the digastic,the sternocleidomastoid ms and the styloid process. • The medial aspect may project as far medially as to be in contact with the lateral wall of the pharynx. www.nayyarENT.com

  23. Anatomy:Parotid Gland • CN VII branches roughly divide the PG into superficial and deep lobes while coursing anteriorly from the stylomastoid foramen to the muscles of facial expression. www.nayyarENT.com

  24. Anatomy: Deep Lobe • The remaining 20% extends medially through the stylomandibular tunnel, which is formed • ventrally by the posterior edge of the ramus • dorsally by the anterior border of the SCM & posterior digastric muscle • deeply and dorsally by the stylomandibular ligament. www.nayyarENT.com

  25. Anatomy--Salivary gland Parotid Ductal System was first described by NicolausStenonius in 1660. www.nayyarENT.com

  26. Anatomy: Parotid Duct • Small ducts coalesce at the anterosuperior aspect of the PG to form Stensen’s duct. • Lined by low cuboidal epithelium ,surrounded by a smooth ms and fibrous tissue. • Runs anteriorly from the gland and lies superficial to the masseter muscle. • It lies - • inferior to the transverse facial artery • Btw the upper and lower buccal branches of the facial nerve. • It is 1-3 mm in diameter • 5cm in length www.nayyarENT.com

  27. Anatomy: Parotid Duct • At the anterior edge of the masseter muscle, Stensen’s duct turns sharply medial and passes through the buccinator muscle, buccal mucosa and into the oral cavity opposite the maxillary second molar. www.nayyarENT.com

  28. Anatomy: Parotid Fascia • Gland encapsulated by a fascial layer that is continuous with deep cervical fascia (DCF). • The fascial envelope is continuous anteriorly with the fascia covering the masseter ms and posteriorly with fascia enveloping SCM ms. • Deep to the gland it is attached to the styloidprocess,tympanic plate and mandible,forming the stylomandibular ligament • The stylomandibular ligament (portion of the DCF) separates the parotid and submandibular gland. www.nayyarENT.com

  29. Parotid fascia • This fascial layer is largely tough and inelastic. • The relatively thin fascia covering the apex of the gland can lead to the spread of sepsis into the parapharyngeal space. www.nayyarENT.com

  30. Parotid Lymphatics • Lymphatic drainage is to the superficial and deep cervical nodes • Preauricular lymph nodes (LN) in the superficial fascia drain the temporal scalp, upper face, anterior pinna • LN within the gland drain the parotid gland, nasopharynx, palate, middle ear and external auditory meatus www.nayyarENT.com

  31. Parotid: Parasympathetic Innervation • Preganglionic parasympathetic (from CN9) arrives at otic ganglion via lesser petrosal n. • Postganglionic parasympathetic leaves the otic ganglion and distributes to the parotid gland via the auriculotemporal nerve. www.nayyarENT.com

  32. Parotid: SympatheticInnervation • Postganglionic innervation is provided by the superior salivary nucleus and carried by the sympathetic plexus surrounding the carotid vessels. www.nayyarENT.com

  33. Parotid Anatomy: Great Auricular Nerve (C2,C3) • Emerges from the posterior border of the SCM at Erb’s point. • It crosses the mid-portion of the SCM about 6.5cm beneath the EAM. • Passes parallel and superior to the external jugular vein to supply the ear and pre-auricular region. www.nayyarENT.com

  34. Parotid Anatomy: Auriculotemporal Nerve • Branch of V3 • Traverses the upper part of the parotid gland and emerges from the superior surface with the superficial temporal vessels. • It carries sensory fibers from the trigeminal and post-ganglionic parasympathetic (secretory)fibers. www.nayyarENT.com

  35. Parotid Anatomy: Facial Nerve • Emerges at the level of the digastric muscle, through the stylomastoid foramen. • Main trunk divides at the pes anserinus (intraparotid plexus of CN7) into the upper temporofacial and lower cervicofacial divisions. • Each division further subdivides into five branches: temporal, zygomatic,buccal,mandibular and cervical,supplying the ms of facial expression. • Before it enters gland, gives off 3 branches: • Posterior auricular, posterior digastric, stylohyoid www.nayyarENT.com

  36. Parotid Anatomy: Vessels • Retromandibular Vein: located within the substance of the gland , drain into the external jugular vein. • Via facial vein drain into the internal jugular vein. • External carotid : at the inferior level of the gland, the external carotid divides into the superficial temporal and internal maxillary artery. www.nayyarENT.com

  37. Parotid Bed: Deep lobe lies on... • V: internal jugular vein • A: external and internal carotid arteries • N: glossopharyngeal N vagus N spinal accesory N hypoglossal N • S: styloid process styloglossus mm stylohyloid mm www.nayyarENT.com

  38. Submandibular gland • Consist of a larger superficial part and a smaller deep part wrapped arround the posterior border of mylohyoid. • Each is irregular in shape. • About the size of a walnut. www.nayyarENT.com

  39. Submandibular gland • The superficial part is covered by a fibrous capsule,derived from the DCF. • The capsule runs from the greater cornu of the hyoid bone,splits to enclose the gland before blending with the periostium of the mandible along the mylohyoid line medially and the lower border of the body of the mandible laterally. www.nayyarENT.com

  40. Submandibular gland • The superficial part of the gland lies within the submandibular triangle. • It extends from the anterior belly of the digastric anteriorly to the stylomandibular ligament posteriorly. • The lower border of the gland overlies the digastric tendon. www.nayyarENT.com

  41. Submandibular gland • The medial surface lies on the surface of mylohyoid anteriorly, with the nerve to mylohyoid and submental vessels. • Posteriorly is related to the stylohyoid ligament ,styloglossus ,the pharynx and the glossopharyngeal nerve. • The intermediate part of the medial surface overlies hyoglossus, the lingual nerve with its submandibular ganglion,hypoglossal nerve, stylohyoid and posterior belly of the digastric. www.nayyarENT.com

  42. Submandibular gland • The lateral surface lies adjacent to the body of the mandible in the mandibular fossa and the origin of the medial pterygoid. • The inferior surface is covered by skin , platysma and deep cervical fascia. • It is related to the cervical branch of the facial nerve. www.nayyarENT.com

  43. Deep part -submandibular gland • The deep part of the gland lies within the floor of the mouth,lying on the mylohyoid, lateral to the hyoglossus and styloglossus. • Anteriorly it lies adjacent to the posterior end of the sublingual gland • Posteriorly wraps around the posterior free edge of mylohyoid to join the superficial lobe. • It lies btw the lingual nerve above and the hypoglossal nerve below. www.nayyarENT.com

  44. Anatomy--Salivary gland • SubmandibularDuctalSystem was first described byThomas Wharton, 1659 • Sublingual DuctalSystem was described byCasparusBartholinus, 1690 www.nayyarENT.com

  45. Anatomy: Submandibular Duct • It is formed by the coalescence of numerous ducts within the superficial part of the gland before emerging from the medial surface of the gland. • Wharton’s duct passes forward along the superior surface of the mylohyoid adjacent to the lingual nerve. • The nerve winds around the duct, first being lateral, then inferior, and finally medial. www.nayyarENT.com

  46. Anatomy: Submandibular duct • 2-4mm in diameter & about 5cm in length. • It opens into the floor of the mouth thru a punctum adjacent to the lingual frenulum,after passing btw the sublingual gland and genioglossus. • The punctum is a constricted portion of the duct to limit retrograde flow of bacteria-laden oral fluids. www.nayyarENT.com

  47. SubmandibularLymphatics • Submandibular gland drains into the deep cervical group,,particularly the jugulo-omohyoid. www.nayyarENT.com

  48. Nerve supply • Via submandibular ganglion, which receives autonomic fibres from the chorda tympani,the lingual nerve and sympathetic trunk. www.nayyarENT.com

  49. Blood supply • Arterial supply from the facial and lingual arteries • Venous drainage into the corresponding veins. www.nayyarENT.com

  50. Anatomy: Sublingual glands Lie on the superior surface of the mylohyoid muscle and are separated from the oral cavity by a thin layer of mucosa. www.nayyarENT.com

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