Parotid Gland

Description (size, shape, colour, function, hormones)

• paired gland
• on the side of the face
  • immediately below and in front of the external ear
• main portion is
  • superficial
  • somewhat flattened
  • quadrilateral.

Relations (superior/inferior, right/left, anterior/posterior, correlative levels)

• Anterior
  • ramus of the mandible
  • pterygoid and masseter muscles
• Posterior
  • mastoid process
  • EAM
  • anterior border of sternocleidomastoid
• Superiorly
  • zygomatic arch
• Inferiorly
  • tapering shape
  • imaginary line joining the mastoid tip to the angle of the mandible.
• Superficial surface
  • covered by the superficial fascia with branches of the great auricular nerve and the lymph glands and the deep cervical fascia
• Deep surface
  • one part
    • lies on the digastric, styloid process and the styloid muscles
    • projecting below the mastoid and SCM
  • other part
    • lies in front of the styloid process and posterior to the mandibular fossa behind the TM joint
    • lateral to the Carotid vessels, IJV, Xth and XIth cranial nerves
    • separated from the pharyngeal wall by loose connective tissue.

Other relations

• facial nerve
  • courses through the parotid gland
  • gives branches within the substance
  • separates the gland surgically into a superficial and deep lobe
  • formation of the external jugular vein in the gland
• parotid duct
  • Stensen's duct
  • traverses over the masseter and then through the buccinator to enter the oral cavity opposite the upper second molar at the parotid papilla

Support Structures (bones, cartilage)

• no bones or cartilage

Movement (muscles)

• no muscles

Vascular Supply (arterial supply, venous drainage, lymphatic drainage)

• external carotid artery gives the terminal branches in the gland

Innervation (Autonomic, Somatic)

• Although the facial nerve (CN VII)
  • runs through the gland
  • does not control the gland
• Secretion of saliva by the parotid gland is
  • controlled by presynaptic parasympathetic fibres
  • originating in the inferior salivatory nucleus
  • these leave the brain via the glossopharyngeal nerve (CN IX)
  • travel along the tympanic nerve (of Jacobson)
  • pass through the tympanic plexus (located in the middle ear)
  • travel in the lesser petrosal nerve until they
  • reach the otic ganglion. After synapsing,
  • the postganglionic fibers travel as
  • part of the auriculotemporal nerve,
    • a branch of the mandibular nerve (V3) to reach the parotid gland.
• Sympathetic nerves
  • originating from Superior Cervical Ganglion reach the gland with blood vessels.
  • stimulation leads to the production of low volume enzyme rich saliva.
• Parasympathetic stimulation
  • produces a water rich mucus saliva.
• no inhibitory nerve supply to the gland.