Salivary Gland Anatomy and Benign Diseases - الأهلية

• The lecture discusses in detail the anatomy of the Salivary Glands and information on Benign diseases

Salivary Glands

• There are three major pairs of salivary glands
• Sublingual glands are located below either side of the tongue under the floor of the mouth
• Submandibular glands are located below the mandible
• Parotid glands are the largest of the salivary glands
• Salivary glands produce saliva in the mouth via ducts or small openings
• Saliva lubricates the mouth and aids in swallowing and digestion

Parotid Gland

• Develops in the 6th-8th weeks of gestation
• It lies in front and below the ear in the parotid compartment, below the auricle, and between the sternomastoid and ramus of the mandible
• 80% of the gland overlies the Masseter and mandible
• The gland consists of a main part, an accessory part, and the parotid duct
• It is shaped like an inverted three-sided pyramid or wedge
• The apex and base are the superior and inferior aspects of the gland
• There are 3 surfaces: superficial, anteromedial, and posteromedial
• There are 3 borders: anterior, posterior, and medial
• Superior Base is related to the external auditory meatus and tempomandibular joint
• The temporal branch of the facial nerve and the auriculotemporal nerve pass through the gland
• The Inferior apex is related to the posterior belly of digastric and stylohoid muscle
• The cervical branch of the facial nerve and the two divisions of the retromandibular vein pass through the gland
• The anterior border lies between the superficial surface and anteromedial surface
• Structures that emerge from the anterior border, from above downward, include the zygomatic branch of the facial nerve, transverse facial vessels, upper buccal branch of the facial nerve, parotid duct, lower buccal branch of the facial nerve, and mandibular branch of the facial nerve
• The gland's posterior border lies between the superficial surface and posteromedial surface
• The medial border is related to the lateral wall of the pharynx
• The lateral surface is superficial and contains skin and superficial fascia
• The superficial fascia contains the platysma and branches of the great auricular nerve
• The parotid fascia and the deep parotid lymph nodes are embedded in the gland.
• The anteromedial surface extends from outward to inward: masseter muscle, mandible (ramus), and medial pterygoid muscle
• The posteromedial surface is closely related to the mastoid process, styloid process, internal carotid artery, internal jugular vein, and last four cranial nerves. The facial nerve enters the gland in the upper part of this surface
• The external carotid artery is there as well
• Structures within the parotid:
  • Deep: External carotid artery and its 2 terminal branches
  • Intermediate: Retromandibular vein
  • Superficial: Facial nerve
• The facial nerve divides the gland into major superficial and small deep lobes

Parotid Duct (Stensen's Duct)

• The duct arises from the anterior border of the parotid
• It is 4-6 cm in length and 5 mm in diameter
• It runs superficial to the masseter muscle and turns medially 90 degrees to pierce the buccinator muscle
• The duct opens into the oral cavity on the level of the second maxillary molar teeth
• The buccal branch of the facial nerve runs with the parotid duct

Accessory Parotid Gland

• Is found in 20% of people
• Accessory glands are overlying the masseter
• Lies cranial to Stensen's duct
• Has its own blood supply from the transverse facial artery

Capsule, Blood & Nerve Supply, & Lymphatic Drainage:

• The parotid gland has a tight fascial capsule derived from the investing deep fascia of the neck
• Arterial supply is from the external carotid artery inside the gland
• Venous drainage is via the retromandibular vein
• Parasympathetic (secretory) nerve supply is from the glossopharyngeal nerve
• Sympathetic nerve supply is from the plexus around the external carotid artery (ECA)
• Sensory nerve supply is from the auriculo-temporal nerve
• Lymphatic drainage is via the paraparotid lymph nodes (in superficial fascia) that drain the temporal region, scalp, and auricle, and via the intraparotid lymph nodes

Submandibular Glands

• Glands are located in the anterior part of digastric triangle
• Has superficial, deep parts, as well as a duct
• Superficial part is made up of the skin, superficial fascia containing platysma and cervical branch of facial nerve + anterior facial vein + submandibular lymph nodes and deep fascia
• Lateral surface has the mandible, facial artery, mylohyoid nerve and artery
• Medial surface contains the mylohyoid and hypoglossus muscles, and the lingual and hypoglossal nerves, and the submandibular ganglion
• Deep part lies deep to mylohyoid muscle and superficial to hyoglossus muscle
• Above, is the lingual nerve and submandibular ganglion, and below, the hypoglossal nerve

Submandibular Duct (Wharton's Duct)

• The submandibular duct is 5 cm long
• It emerges from the anterior end of the deep part of the gland
• It opens into the floor of the mouth on the summit of sublingual papilla
• The lingual nerve has triple relation to the duct: first lateral then below then medial
• Blood supply is the facial and lingual arteries, and the common facial or lingual vein
• Lymphatic drainage goes to submandibular and upper deep cervical lymph nodes
• The parasympathetic (secretomotor) nerve supply from chorda tympani(branch from facial nerve) pass to the gland through lingual nerve
• Sympathetic plexus around facial artery provides sympathetic innervation
• Sensory nerve supply from the lingual nerve.

Benign Diseases of Salivary Glands - Sialadenitis

• It is the inflammation of salivary glands
• Types of sialadenitis:
• Acute:
  • Epidemic: includes mumps and influenza
  • Acute suppurative: encompassing acute parotitis and acute submandibular sialadenitis
• Chronic:
  • Endemic: associated with parasitic infestation (anklyostoma), liver cirrhosis, and malnutrition
  • Chronic pyogenic: includes chronic parotitis and chronic submandibular sialadenitis

Acute Suppurative Sialadenitis:

• Etiology:
  • Poor oral hygiene
  • Obstruction of the salivary duct by food particles, foreign bodies, or stones
  • Dehydration, specially postoperatively
  • Debility
• Organisms: Commonly caused by Staph. aureus, streptococci, and pneumococci
• Route of entry:
  • Direct: along the duct from the mouth (commonest) or from a nearby focus
  • Blood borne
• Site: The parotid is the most common gland involved
• Characters: The gland and duct are congested, edematous and may suppurate

Clinical Picture of Acute Suppurative Sialadenitis

• General:
  • Toxemic symptoms such as fever and headache
• Local:
  • Pain: Early, dull aching, later becomes severe and throbbing
  • Swelling: Elevating the lobule of the ear-red-warm-edema-tender-fluctuate (late due to thicker parotid fascia)
  • Opening of the duct is red and raised
  • Trismus: Restricted movement of the temporomandibular joint
• Investigations
  • Leucocytosis
  • X-ray film indicates calcifications or stones
  • U.S ultrasound
• Complications:
  • Abscess: Rupture may lead to a fistula
  • Chronicity and stone formation
  • Spread: Ludwig's angina
• Conservative treatment
  • General: Rest, antibiotics (clindamycin), analgesics, and tonics
  • Local: Hot fomentation, H2O2 mouth wash, KI as sialogogue
  • Observation:
    • General: Pulse, temperature
    • Local: Swelling
• Surgical Treatment
  • Indications:
    • Failure of conservative treatment
    • Signs of suppuration (abscess formation)
• Procedure:
  • Parotid abscess: A vertical skin incision in front of the ear
  • Submandibular abscess: A skin incision parallel to the lower border of the mandible 1.5 inches below and in front of the angle of the mandible to avoid injury of the mandibular branch of the facial nerve

After 3 days of conservative treatment, the patient improves or worsens

• If the patient improves
  • Continue conservative treatment until complete cure
• If the patient worsens
  • Shows signs of suppuration, including throbbing pain, hectic fever, and pitting edema
  • Then proceed with incision and drainage

Chronic Sialadenitis

• Two types: chronic calcular and chronic non-calcular sialadenitis

Chronic Calcular Sialadenitis:

• Etiology:
  • Infection causes stasis that gives time for stone formation
  • Stasis caused by sepsis, stricture, or foreign body
  • Stones lie in the gland or in the duct
  • Submandibular glands to parotid ratio is 50:1 because the secretions of submandibular are more viscid
• Pathology:
  • Parotid secretion is watery as it consists of multiple serous acini
  • Submandibular secretion is mucoid, viscid, and tenacious
  • The duct opens in the floor of the mouth leading to obstruction by food particles
  • Drainage of submandibular gland is independent
  • The stone number may be single or multiple
  • Stone composition: composed of Calcium, Mg phosphate, and carbonate
• Type of patient:
  • Male > female
  • Occurs in middle and old age

Symptoms:

• Pain:
  • If the stone is the Gland, it causes a dull aching pain
  • If the stone is in the Duct, it causes colicky pain
  • May refer to the tip of the tongue or teeth due to irritation of lingual
  • Increased pain with meal and mastication
• Swelling:
  • The gland is enlarged and its size is increased after meal
  • Stone in the submandibular duct may be felt through floor of mouth
• Discharge:
  • Bloody or even purulent discharge may be seen coming from duct

Signs:

• Lemon test:
  • Pain and gland increase in size when the patient is given a lemon to suck
• Gland:
  • Enlarged
  • Tender
  • Cannot be rolled over lower border of mandible
• Bidigital palpation: the gland better felt from inside the mouth
• The duct may be palpated with stone in it
• Opening of duct is seen red, raised, discharging blood or pus
• The stone may be seen peeping from the duct opening

Investigations:

• Plain X-Ray: Stones are 100% radio opaque and may be hidden by the mandible
• Sialography:
  • A radio-opaque material as lipidolor hypaque(Na diatrizoate)
• A volume of 0.5-2 ml is injected in the canulated duct to delineate it and shows sialactasis behind the stone
• Neck ultrasound

Differential diagnosis :

• Enlarged Submandibular Salivary Gland, versus Lymph node
• Single swelling
• Positive lemon test
• Cannot be rolled around the mandible with a preserved sulcus & best palpated digitally from inside is indicative of Salivary gland
• Enlarged lymph node
• Multiple swellings
• Negative lemon test
• Can be rolled around mandible & best palpated externally
• Submandibular stone versus parotid

Stone treatment:

• Stone in the duct meatotomy is performed by,
  • peeping the stone from the orifice using meatotomy
  • under local anesthesia the duct is underrun by an anchoring stitch to avoid slippage of stone to the gland
  • then slit the duct open from the orifice to the stone and remove
  • leave the duct open after to allow better drainage
• Treat any Recurrent ductal stones via a Submandibular sialadenectomy
• Stone in the gland submandibular sialadenectomy is performed
• Conservative Parotidectomy is carried out due to the possibility of Salivary Fistula from a diseased cystic deep lobe

Chronic Non-Calcular Sialadenitis -

• Etiology:
  • Poor oral hygiene
  • Obstruction of salivary duct by food particles
  • Imperfect drainage of acute sialoadenitis
• Submandibular gland is the most common gland involved

Submandibular Sialadenectomy Technique

• Incision starts at 1.5 inches below and in front of the mandible's angle, curving towards the hyoid bone and up towards the symphysis menti
• Important to avoid mandibular branch injury to the facial nerve by not elevating skin flaps

Sialadenectomy Complications :

• Injury of the mandibular branch of the facial nerve, may drop the angle of the mouth.
• Injury of the hypoglossal nerve results in the deviation of the tongue to the same side and atrophy of the tongue
• Injury of the lingual nerve results in loss of sensation to the anterior 2/3 of the tongue.
• Injury of the pharynx

Autoimmune Diseases of Salivary Glands:

• Von Mickulicz Disease:
  • It is an autoimmune disease, distinguished by salivary glands, particularly the enlargement of both parotid, both submandibular, and both lacrimal glands
  • May be a precursor to lymphoma of the salivary gland
  • The salivary glands are the seat of heavy lymphocytic infiltration
  • Causes narrowing of the palpebral fissure due to enlargement of lacrimal gland and a dry mouth resembling parchment
  • This disease responds to prednisolone
• Sjogren syndrome:
  • Evident with dry eyes and generalized arthritis
• Sicca syndrome:
  • Manifests as dry mouth and dry eyes