PAROTID GLAND

parotid region

• features
  • largest of salivary gland
  • situated below external acoustic meatus
  • between the ramus of mandible and sternocleidomastoid
  • skin over gland supplied by greater auricular nerve
• structures within parotid gland
  • arteries
    • external carotid artery enters gland through posteromedial surface
    • maxillary artery leaves the gland through its anteromedial surface
    • superficial temporal artery gives transverse facial artery and emerges at the
      • anterior part of superior surface
  • veins
    • retromandibular vein is formed within the gland
      • union of
        • superficial tempora and maxillary veins
    • in lower part of gland vein divides in t
      • these emerge close the apex (lower pole
        • anterior division
        • posterior division
  • nerve
    • facial nerve is the nerve of second branchial arch
    • leaves the skull by passing through stylomastoid foramen
    • extracranial course
      • 1. crosses the lateral side of base of styloid process
        • then enters the posteromedial surface of partodi gland
    • branches at its exit from stylomastoid foramen
      • communicating branches with adjacent cranial and spinal nerves
      • posterior auricular nerve arises just below the stylomastoid foramen
        • ascends between mastoid process and external acoustic meatus
          • supplies
            • auricularis posterior
            • occipitalis
            • intrinisic muscles on back of auricle
      • digastric branch arises close to previous nerve
        • short and supplies posterior belly of digastric
      • stylohyoid branch arises with digastric branch
        • long and supplies stylohyoid muscle
    • terminal branches
      • temporal branches cross zygomatic arch and supply
        • auricularis anterior
        • auricularis superior
        • intrinsic muscles on the lateral side of ear
        • frontalis
        • orbicularis oculi
        • corrugator supercili
      • zygomatic branches
        • run across zygomatic bone
          • supply orbicularis oculi
      • buccal branches are two in number
      • marginal mandibular branch
        • runs below the angle of mandible
          • deep to platysma
        • crosses body of mandible supplies
          • muscles of lower lip and chin
      • cervical branch
        • emerges from apex of parotid gland
          • runs downwards and forwards in the neck to supply platysma
    • bells palsy
      • sudden paralysis of facial nerve at stylomastoid foramen
        • results in asymmetry of corner of mouth
        • inability to close eye
        • dissapearance of nasolabial fold
        • loss of wrinkling of skin of forehead on same side
• nerve supply
  • parasympathetic nerves are secretomotor
    • reach the gland through auriculotemporal nerve
    • preganglionic fibres begin in inferior salivatory nucleus
      • pass through glossopharyngeal nerve
        • tympanic branch
        • relay in otic ganglion
  • sympathetic nerves
    • postganglionic
      • vasomotor
        • derived from plexus around middle meningeal artery
      • travel along branches of maxillary,external carotid artery and their branches
  • sensory nerves
    • to the gland come from
      • auriculotemporal nerve
    • parotid fascia innervated by sensory fibres of great auricular nerve
• parotid duct or stensons duct
  • superiorly
    • accessory parotid gland
    • transverse facial vessels
    • upper buccal branch of facial nerve
  • inferiorly
    • lower buccal branch of facial nerve
    • anterior border of masseter
      • parotid duct turns medially and pierces
        • buccal pad of fat
        • buccopharyngeal fascia
        • buccinator
• contains
  • largest salivary gland
  • histology
    • it is a serous acini
• external features
  • surfaces
    • superior (base of pyramid)
      • forms the upper end of the gland
        • small and concave
          • related to cartilaginous part of external acoustic meatus
          • posterior surface of temporomandibular joint
          • superficial temporal vessels
          • auriculotemporal nerve
  • superficial
    • largest surface
    • covered by
      • skin
      • superficial fascia
        • containing anterior branches of great auricular nerve
        • preauricular or superficial parotid lymph nodes
        • posterior fibres of platysma
        • risorius
      • parotid fascia which is thick and adherent
  • anteromedial
    • grooved by posterior border of ramus of mandible
    • related to
      • masseter
      • lateral surface of temporomandibular joint
      • posterior border of the ramus of mandible
      • medial pterygoid
      • emerging branches of facial nerve
  • posteromedial
    • moulded to mastoid
    • moulded to styloid processs
    • structures attached to them
    • related to
      • mastoid process
      • sternocleidomastoid
      • posterior belly of digastric
      • styloid process with structures attached to it
      • external carotid artery and facial nerve
        • enter the gland through this surface
      • internal carotid artery lies deep to styloid process
  • relations
  • borders
    • anterior
      • separates superficial surface from anteromedial surface
      • extends from anterior part of the superior surface to the apex
      • following structures emerge at this border
      • parotid duct
      • terminal braches of facial nerve
      • transverse facial vessels
    • posterior
      • separates superficial surface from posteromedial surface
      • overlaps sternocleidomastoid
    • medial / pharyngeal edge
      • separates anteromedial surface from posteromedial surface
      • related to lateral wall of pharynx
  • blood supply
  • parotid lymph nodes
• CLINICAL ANATOMY
  • parotid abscess
    • caused by spread of infection from opening of parotid duct
    • drained by making holes (hiltons method)
  • mixed parotid tumour is slow growing tumour
  • parotid calculi may be formed in the parotid duct