SALIVARY GLANDS ANATOMY & APPLIED ASPECTSJoel D’silva

Department of Oral & Maxillofacial Surgery

INTRODUCTIONThe salivary glands are exocrine glands, glands with ducts, that produce saliva and pour their secretion in the oral cavity

Major (Paired) Parotid Submandibular Sublingual

MinorThose in the Tongue, Palatine Tonsil, Palate, Lips and Cheeks

DEVELOPMENT

STAGES OF DEVELOPMENT

STAGE 1

Bud formation: Introduction of the oral epithelium by underlying mesenchyme

STAGE 2

Formation and growth of epithelial cord

STAGE 3Initiation of branching in terminal parts of epithelial cord and continuation of glandular differentiation

STAGE 4

Dichromatous branching of epithelial cord and lobule formation

STAGE 5

Canalization of presumptive ducts

STAGE 6Cytodifferentiation

UNDERSTANDING THE HISTOLOGY

PAROTID GLAND

Largest Average Wt - 25gmIrregular lobulated mass lying mainly below the external acoustic meatus between mandible and sternomastoid.On the surface of the masseter, small detached part lies b/w zygomatic arch and parotid duct-accessory parotid gland or ‘socia parotidis’

Parotid Capsule

• Derived from investing layer of deep cervical fascia.

• Superficial lamina-thick, closely adherent-sends fibrous septa into the gland.

• Deep lamina-thin- attached to styloid process, mandible and tympanic plate.

• Stylomandibular ligament.

External Features

•Resembles an inverted 3 sided pyramid

•Four surfaces• Superior(Base of the Pyramid)• Superficial• Anteromedial• Posteromedial

•Separated by three borders

•Anterior• Posterior•Medial

Relations

• Superior Surface • Concave• Related to

• Cartilaginous part of ext acoustic meatus• Post. Aspect of

temperomandibular joint• Auriculotemporal Nerve• Sup. Temporal vessels

• Apex• Overlaps posterior belly of

digastric and adjoining part of carotid triangle

• Superficial Surface• Covered by • Skin• Superficial fascia containing

facial branches of great auricular N• Superficial parotid lymph

nodes and post fibers of platysma

•Anteromedial Surface•Grooved by posterior border of ramus of mandible

•Related to• Masseter• Lateral Surface of

temperomandibular joint• Medial pterygoid muscles• Emerging branches of Facial

N

• Posteromedial Surface

• Related • to mastoid process with

sternomastoid and posterior belly of digastric.

• Styloid process with structures attached to it.

• External Carotid A. which enters the gland through the surface

• Internal Carotid A. which lies deep to styloid process

BORDERS

•Anterior border

• Separates superficial surface from anteromedial surface.

• Structures which emerge at this border

• Parotid Duct• Terminal Branches of

facial nerve• Transverse facial

vessels

• Posterior Border

• Separates superficial surface from posteromedial surface• Overlaps sternomastoid

•Medial Border

• Separates anteromedial surface from posteromedial surface• Related to lateral wall of pharynx

Structures within the parotid gland

ARTERIES

VEINS

NERVES

• Facial Nerve trunk lies approximately 1 cm inferior and 1 cm medial to tragal cartilage pointer of external acoustic meatus.

Parotid Duct• ductus parotideus;

Stensen’s duct

• 5 cm in length

• Appears in the anterior border of the gland

• Runs anteriorly and downwards on the masseter b/w the upper and lower buccal branches of facial N.

•At the anterior border of masseter it pierces

• Buccal pad of fat• Buccopharyngeal fascia• Buccinator Muscle

• It opens into the vestibule of mouth opposite to the 2nd upper molar

Surface anatomy of Parotid Duct

• Corresponds to middle third of a line drawn from lower border of tragus to a point midway b/w nasal ala and upperlabial margin

Blood supply

• Arterial• Branches of Ext.

Carotid A• Venous

• Into Ext. Jugular Vein

Lymphatic DrainageUpper Deep cervical nodes via Parotid nodes

NERVE SUPPLY

•Parasymapthetic N• Secretomotor via

auriculotemporal N

•Symapathetic N• Vasomotor• Delivered from plexus

around the external carotid artery

•Sensory N• Reach through the Great

auricular and auriculotemporal N

Applied aspects

• Parotid swellings are very painful due to the underlying nature of the parotid fascia.• Mumps is infection of salivary gland caused by paromyxovirus which will cause severe pain

Incision

• Lazy ‘S’ incision• Pre-auricular—mastoid-cervical incision

• During surgical removal of parotid gland for any tumour the facial nerve is preserved by removing the glands in two parts superficial and deep lobe separately.

Superficial parotidectomy

• Hypotensive anaesthesia• Head up position • Infiltration with 1:80,000 LA with adrenaline• Long term paralytic agents should be avoided for C VII monitoring whenever indicated

Facial Nerve injury

• A parotid abscess may be caused by the spread of infection from the oral cavity.• An infection may also spread due to the parotid lymph node draining an infected area

• Parotid abscess is best drained by horizontal incision according to Hiltons method of incision and drainage.

 Vertical incision on skin but transverse incision on the parotid fascia to safeguard facial nerve 

and branches

• Frey's syndrome

• The lobule of the ear is often pushed up in parotid swelling• For tumours of the parotid gland incision biopsy is not indicated as it will cause the seeding of the tumour 

Inflamatory diseases of parotid

Acute suppurative parotitis

Acute parotitis (mumps parotitis)

Recurrent subacute parotitis / chronic parotitis

Neoplasms of the salivary gland

• 75% occur in the parotid glands.• In parotid glands, 80% of tumors are benign.• Of these 80% are Pleomorphic adenomas.

• 15% of salivary tumors occur in submandibular glands.• Of these 50% are benign and 50% and malignant.

• In carcinomas mucoepidermoid ca> adenoid cystic ca > adenocarcinoma

• 10% of salivary tumors occur in sublingual and minor salivary glands• 60-70% of these are malignant

Classification

Epithelial tumors

Connective tissue tumors

Epithilial tumors

• Benign • Pleomorphic adenoma (Mixed tumor)• Oxyphil adenoma• Papillary cystadenoma lymphomatosum (Warthin’s tumor)• Basal cell adenoma

Epithelial tumors

• Malignant • Mucoepidermoid carcinoma• Adenoid cystic carcinoma• Acinic cell ca• Papillary adenocarcinoma• SCC• Undifferentiated ca• Ca arising in pleomorphic adenoma

Connective tissue tumors

• Benign • Hemangioma • Lipoma• Neurilemmoma• Fibroma

• Malignant • Malignant lymphoma• Above mentioned benign tumors may turn malignant.

submandibular salivary gland

Submandibular Glands are….• Irregular in shape

• Large superficial and small deeper part continous with each other around the post. Border of mylohyoid

Superficial Part• Situated in the digastric triangle•Wedged b/w body of mandible and mylohyoid• 3 surfaces

• Inferior, Medial, Lateral

Capsule

• Derived from deep cervical fascia

• Superficial Layer is attached to base of mandible

• Deep layer attached to mylohyoid line of mandible

Relations

• Inferior- covered by • Skin• Superficial fascia containing

platysma and cervical branches of facial N• Deep Fascia• Facial Vein• Submandibular Nodes

• Lateral surface• Related to submandibluar

fossa on the mandible• Madibular attachment of

Medial pterygoid• Facial Artery

• Medial surface

• Anterior part is related to myelohyoid muscle, nerve and vessels

• Middle part - Hyoglossus, styloglossus, lingual nerve, submandibular ganglion, hypoglossal nerve and deep lingual vein.

• Posterior Part - Styloglossus, stylohyoid ligament,9th nerve and wall of pharynx

• Deep part• Small in size

• Lies deep to mylohyoid and superficial to hyoglossus and styloglossus

• Posteriorly continuous with superficial part around the posterior border of mylohyoid

Submandibular Duct

• Whartons duct• 5 cm long• Emerges at the anterior end of deep

part of the gland• Runs forwards on hyoglossus b/w

lingual and hypoglossal N• At the ant. Border of hyoglossus it is

crossed by lingual nerve• Opens in the floor of mouth at the side

of frenulum of tongue

Blood supply and lymphatics

• Arteries• Branches of facial and lingual arteries

• Veins• Drains to the corresponding veins

• Lymphatics• Deep Cervical Nodes via submandibular

nodes

Nerve supply

• Parasymapthetic fibers from chorda tympani

• Sensory fibers from lingual branch of mandibular nerve

• Sympathetic fibers from plexus on facial A

Applied aspects

• The formation of calculus is more common in the submandibular gland than in the parotid.• For excision of the submandibular salivary gland( for calculus or tumour), a skin crease incision is as a rule, given more than 1inch( 2.5cm) below the angle of the jaw• A stone in the submandibular duct(wharton’s duct) can be palpated bimanually in the floor of the mouth and can even be seen if sufficiently large.

Tumors of submandibular glands• Tumors in this gland are uncommon• Enlargement is more due to calculus • Of all tumors, mixed tumor is most common• Swelling is hard but not stony hard and should be differentiated from submandibular lymph node

Submandibular gland excision• Indications :• Chronic sialoadenitis• Stone in submandbular gland• Submandibular gland tumors

Incision

• Placed 2-4 cm below the mandible, parallel to it• Preserve : • Marginal mandibular nerve• Lingual nerve• Hypoglossal nerve

Complications

• Hemorrhage• Infection• Injury to mandibular nerve, lingual nerve , hypoglossal nerve

Sublingual Salivary Glands

• smallest of the three glands

• weighs nearly 3-4 gm

• Lies beneath the oral mucosa in contact with the sublingual fossa on lingual aspect of mandible.

Relations

•Above• Mucosa of oral floor, raised as

sublingual fold

•Below • Myelohyoid Infront• Anterior end of its fellow

•Behind• Deep part of Submandibular gland

• Lateral•Mandible above the anterior part of mylohyoid line

•Medial•Genioglossus and separated from it by lingual nerve and submandibular duct

Duct

• Ducts of Rivinus• 8-20 ducts• Most of them open directly into

the floor of mouth• Few of them join the

submandibular duct

•Blood supply• Arterial from sublingual and

submental arteries• Venous drainage corresponds to

the arteries

•Nerve Supply• Similar to that of submandibular

glands( via lingual nerve , chorda tympani and sympathetic fibers)

Sublingual and minor salivary gland diseases

• Mucous cyst (retention cyst) : Ranula, sailoliths • Inflammatory salivary gland diseases • Tumors as described before but it rarely effects sublingual glands

Applied aspects

• The structures at risk during dissection of the gland are the submandibular duct and the lingual nerve.• The duct lies superficially in the floor of the mouth medial to the sublingual fold, and is crossed inferiorly by the nerve which then enters the tongue• The sublingual artery and vein also lie on the medial aspect of the gland close to the submandibular duct and lingual nerve.

Incision

Ann R Coll Surg Engl 1994; 76: 108-109

REFERENCES

• Anatomy – by B.D.Chaurasia• Oral anatomy- by Sicher and DuBruls• Gray’s anatomy• Oral and maxillofacial surgery-by Nilima Malik• Oral and maxillofacial surgery- Kruger• Ann R Coll Surg Engl 1994; 76: 108-109