Anatomy of salivary glands

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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. - PowerPoint PPT Presentation

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Anatomy of salivary glands

Contributed By :- Dr. Nafisa ParveenJawahar Lal Nehru Medical CollegeAligarh Muslim University, India

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Anatomy of salivary glands

7/29/2012www.nayyarENT.com1EmbryologyThe 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.

7/29/2012www.nayyarENT.com2EmbryologyThe stroma (capsule and septae) of the glands originates from mesenchyme that may be mesodermal or neural crest in origin. 7/29/2012www.nayyarENT.com3Parotid developmentAlthough 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.7/29/2012www.nayyarENT.com4Parotid developmentTherefore, 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.7/29/2012www.nayyarENT.com5EmbryologyThe 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.

7/29/2012www.nayyarENT.com6EmbryologyElongation 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.

7/29/2012www.nayyarENT.com7Duct CanalizationCanalization 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.

7/29/2012www.nayyarENT.com8Acinar cellsAt around the 7-8th month in utero, secretory cells (acini) begin to develop around the ductal system. 7/29/2012www.nayyarENT.com9Acinar cells of Salivary GlandsClassified 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.7/29/2012www.nayyarENT.com10Salivary gland secretory unitComposed of terminal aciniIntercalated, striated and excretory ductsMyoepithelial cells

7/29/2012www.nayyarENT.com11Salivary gland secretory unitBasic 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.7/29/2012www.nayyarENT.com12Salivary gland secretory unitThe acinar ducts coalesce into intercalated ducts ,subsequently striated ducts composed of columnar cells, then united into the main excretory duct of the gland.7/29/2012www.nayyarENT.com13Salivary gland secretory unitThe 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.7/29/2012www.nayyarENT.com14Major glands/SecretionsMajor SG are paired structures and include the parotid, submandibular and sublingual

Parotid: serousSubmandibular: mucous & serousSublingual: mucous 7/29/2012www.nayyarENT.com15Parotid glandLargest 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.

7/29/2012www.nayyarENT.com16Anatomy: Parotid GlandNearly 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

7/29/2012www.nayyarENT.com17Anatomy:Parotid GlandExtensions of PG project to mastoid processDown the anterior aspect of the SCM for a short distanceAround the posterior border of the mandible.Superiorly to the to inferior margin of the zygomatic arch7/29/2012www.nayyarENT.com18Parotid glandThe 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.

7/29/2012www.nayyarENT.com19Parotid glandThe 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.7/29/2012www.nayyarENT.com20Parotid glandThe 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.7/29/2012www.nayyarENT.com21Parotid glandPosteromedial 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.7/29/2012www.nayyarENT.com22Anatomy:Parotid GlandCN VII branches roughly divide the PG into superficial and deep lobes while coursing anteriorly from the stylomastoid foramen to the muscles of facial expression.

7/29/2012www.nayyarENT.com23Anatomy: Deep LobeThe 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 muscledeeply and dorsally by the stylomandibular ligament.7/29/2012www.nayyarENT.com24Parotid Ductal System was first described by Nicolaus Stenonius in 1660.

Anatomy--Salivary gland 7/29/2012www.nayyarENT.com25Anatomy: Parotid DuctSmall ducts coalesce at the anterosuperior aspect of the PG to form Stensens 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 arteryBtw the upper and lower buccal branches of the facial nerve.It is 1-3 mm in diameter5cm in length

7/29/2012www.nayyarENT.com26Anatomy: Parotid DuctAt the anterior edge of the masseter muscle, Stensens duct turns sharply medial and passes through the buccinator muscle, buccal mucosa and into the oral cavity opposite the maxillary second molar.7/29/2012www.nayyarENT.com27Anatomy: Parotid FasciaGland 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 styloid process,tympanic plate and mandible,forming the stylomandibular ligament The stylomandibular ligament (portion of the DCF) separates the parotid and submandibular gland.

7/29/2012www.nayyarENT.com28Parotid fasciaThis 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.7/29/2012www.nayyarENT.com29 Parotid LymphaticsLymphatic drainage is to the superficial and deep cervical nodesPreauricular lymph nodes (LN) in the superficial fascia drain the temporal scalp, upper face, anterior pinnaLN within the gland drain the parotid gland, nasopharynx, palate, middle ear and external auditory meatus7/29/2012www.nayyarENT.com30Parotid: Parasympathetic InnervationPreganglionic 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.7/29/2012www.nayyarENT.com31Parotid: SympatheticInnervationPostganglionic innervation is provided by the superior salivary nucleus and carried by the sympathetic plexus surrounding the carotid vessels.7/29/2012www.nayyarENT.com32Parotid Anatomy: Great Auricular Nerve (C2,C3)Emerges from the posterior border of the SCM at Erbs 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.7/29/2012www.nayyarENT.com33Parotid Anatomy: Auriculotemporal NerveBranch of V3Traverses 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.7/29/2012www.nayyarENT.com34Parotid Anatomy: Facial NerveEmerges 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, stylohyoid7/29/2012www.nayyarENT.com35Parotid Anatomy: VesselsRetromandibular 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.7/29/2012www.nayyarENT.com36Parotid Bed: Deep lobe lies on...V: internal jugular veinA: external and internal carotid arteriesN: glossopharyngeal N vagus N spinal accesory N hypoglossal NS: styloid process styloglossus mm stylohyloid mm7/29/2012www.nayyarENT.com37Submandibular glandConsist 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.7/29/2012www.nayyarENT.com38Submandibular glandThe 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.7/29/2012www.nayyarENT.com39Submandibular glandThe 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.7/29/2012www.nayyarENT.com40Submandibular glandThe 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.7/29/2012www.nayyarENT.com41Submandibular glandThe 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.7/29/2012www.nayyarENT.com42Deep part -submandibular glandThe 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 glandPosteriorly 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. 7/29/2012www.nayyarENT.com43Submandibular Ductal System was first described byThomas Wharton, 1659

Sublingual Ductal System was described byCasparus Bartholinus, 1690Anatomy--Salivary gland7/29/2012www.nayyarENT.com44Anatomy: Submandibular DuctIt is formed by the coalescence of numerous ducts within the superficial part of the gland before emerging from the medial surface of the gland.Whartons 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.7/29/2012www.nayyarENT.com45Anatomy: Submandibular duct2-4mm 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.

7/29/2012www.nayyarENT.com46 Submandibular Lymphatics Submandibular gland drains into the deep cervical group,,particularly the jugulo-omohyoid.7/29/2012www.nayyarENT.com47Nerve supplyVia submandibular ganglion, which receives autonomic fibres from the chorda tympani,the lingual nerve and sympathetic trunk.7/29/2012www.nayyarENT.com48Blood supplyArterial supply from the facial and lingual arteriesVenous drainage into the corresponding veins.7/29/2012www.nayyarENT.com49Anatomy: Sublingual glandsLie on the superior surface of the mylohyoid muscle and are separated from the oral cavity by a thin layer of mucosa.

7/29/2012www.nayyarENT.com50Sublingual glandSmallest paired salivary gland.Almond shaped.4g weightPosteriorly they contact the deep part of the submandibular glandMedially they are separated from the genioglossus by the lingual nerve and submandibular duct.

7/29/2012www.nayyarENT.com51 Sublingual glandsThe ducts of the sublingual glands are called Bartholins ducts. In most cases, Bartholins ducts consists of 8-20 smaller ducts of Rivinus. These ducts are short and small in diameter.

7/29/2012www.nayyarENT.com52 Sublingual glandsThe ducts of Rivinis either openindividually into the FOM near the punctum of Whartons ducton a crest of sublingual mucosa called the plica sublingualisopen directly into Whartons duct

7/29/2012www.nayyarENT.com53Blood supplyVia the sublingual and submental vessels.7/29/2012www.nayyarENT.com54Nerve supplyVia submandibular ganglion, which receives autonomic fibres from the chorda tympani,the lingual nerve and sympathetic trunk.7/29/2012www.nayyarENT.com55Minor salivary glands

600-1000 in numbers.

the minor salivary glands of mouth include the buccal, labial,lingual,palatal and palatoglossal glands. The buccal and labial glands contains both mucous and serous elements. The palatal, lingual and palatoglossal glands are mucous glands .7/29/2012www.nayyarENT.com56PhysiologyPhysiologic control of the SG is almost entirely by the autonomic nervous system; parasympathetic effects predominate. If parasympathetic innervation is interrupted, glandular atrophy occurs. Normal saliva is 99.5% waterNormal daily production is 0.5LSalivary flow rates are approximately 0.3ml/min when unstimulated.Rising to 1.5-2ml/min when stimulated.7/29/2012www.nayyarENT.com57physiologyDuring sleep salivary flow rate is negligible.In unstimulated state parotid gland contributes approximately 20%Submandibular gland approximately 65%Sublingual and minor salivary glands the remainder.When stimulated the parotid contribution rises to 50% 7/29/2012www.nayyarENT.com58 thank you

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