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