The parotid gland is the largest salivary gland located below and in front of the ear. It secretes saliva through the parotid duct into the mouth. The parotid gland receives parasympathetic input which stimulates watery secretion and sympathetic input which stimulates thicker secretion. It is supplied by the external carotid artery and drains into the retromandibular vein. The facial nerve passes through the gland and its branches are at risk during parotid surgery which can lead to Frey's syndrome.
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Nerves and vessels of parotid gland
1.
2. Largest of the salivary
glands
Serous type
Average weight of 25 gm
Extent : lies below the
external acoustic meatus
between the mandible and
sternocleidomastoid
Location : Retromandibular
fossa
3. Shape : inverted pyramidal
It has 4 surfaces:
Superior surface
Superficial surface
Anteriomedial surface
Posteriomedial surface
It tapers inferiorly to a
blunt apex
It secretes saliva through
Stenson Duct or Parotid
Duct in the oral cavity
4. It comes out of the cranial
cavity through the
stylomastoid foramen at the
base of the skull between the
styloid and mastoid
processes of temporal bone
It immediately gives off the
branches :
Nerve to Posterior belly of
digastric
Nerve to Stylohyoid
Posterior auricular nerve
5. Next the nerve enters the parotid gland from
its posteriomedial aspect and passes forwards
and downwards behind the mandibular ramus
6. Within the substance of
the gland it branches into:
Temporofacial trunk
(superior)- runs upwards
and divide into
o Temporal branch - crosses
the zygomatic arch to supply
the auricularis anterior and
superior, intrinsic muscles on
the lateral aspect of the ear,
frontal belly of
occipitofrontalis muscle,
orbicularis oculi and
corrugator supercilli
o Zygomatic branch - runs
below and parallel to the
zygomatic arch to supply the
orbicularis oculi
7. Cervicofacial trunk (inferior) – passes
downwards and forwards and divides into:
o Buccal branches - 2 in number
1. Upper buccal nerve - runs above the parotid
duct
-Supply zygomaticus major and levator labii
superioris
-Form an infra orbital plexus with superior
labial branches of infraorbital nerve
-Also supply levator anguli oris, zygomaticus
minor and levator labii superioris aleque
nasi
2. Lower buccal nerve - runs below the parotid
duct
- Supply buccinator and orbicularis oris
- Communicate with buccal branch of
mandibular nerve
8. o Marginal mandibular branch – Run forwards
towards the angle of mandible under platysma
- Crosses the body of mandible to supply risorius
and muscles of lower lip and chin
- Communicates with the mental nerve
o Cervical branch – Emerges from the lower part of
parotid gland and runs anterioinferiorly under
platysma to the front of the neck
- Supplies platysma
- Communicates with transverse cutaneous
cervical nerve
These 5 terminal branches radiate like a goose
foot through the anterior border of the gland,
this branching pattern is termed as pes-
anserinus
9.
10. The parotid gland is supplied by:
PARASYMPATHETIC(SECRETOM
OTOR)SUPPLY-derived from
auriculo temporal nerve
Its stimulation produces watery
secretion
SYMPATHETIC SUPPLY-derived
from the sympathetic plexus
around the external carotid artery
Stimulation produces thick sticky
secretion
SENSORY SUPPLY- derived from
Auriculo-temporal nerve
Great auricular nerve
11.
12. Arise from the cells of the ganglion and pass
through the auriculo-temporal nerve to
supply the parotid gland
13.
14.
15. From the external carotid artery
and its branches and superficial
temporal arteries
It pierces the lower part of
posteriomedial surface to enter
the gland where it occupies the
deep zone of the gland
Within the gland it divides into
Maxillary artery- emerges from
the anteriomedial surface
Superficial temporal artery- gives
off its transverse facial branch
which emerges through the
anterior border and it ascends to
leave its upper limit
Posterior auricular artery may also
branch from it and leave by its
posteriomedial surface
16.
17. Into retromandibular vein
and external jugular vein
The retromandibular vein
is formed by the union of
Maxillary veins
SuperficialTemporal veins
It lies superficial to
external carotid artery
It descends in the parotid
gland and emerges behind
the apex of the gland
18. Here it usually divides into :
Anterior branch – passes forward to join the
facial vein and form the common facial vein
Posterior branch – joins the posterior auricular
vein to form the external jugular vein
19.
20. CONNECTED BY
ISTHMUS
PAROTID
GLAND
SUPERFICIAL
LOBE(LARGE)
DEEP
LOBE(SMALL)
The branches of facial nerve passes forward through the isthmus .
The plane in between the superficial and deep lobes in which nerves and
veins lie has been designated as ‘Patey’s Faciovenous Plane’.
SIGNIFICANCE: This plane helps the surgeons to remove the parotid
tumor without damaging the nerve.
21. Also known as gustatory sweating or
auriculo-temporal nerve syndrome
Commonly occurs after parotid surgery
or trauma
It reflects the aberrant innervation of
sweat glands on the face by regrowing
parasympathetic secretomotor axons
that would have previously innervated
the parotid gland
It is characterized by
o Sweating
o Warmth
o Redness of the face
as a result of salivary stimulation by the smell
or taste of food