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.
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