MADE BY: ANJALI MBBS 1ST YR 2013-14

NERVES AND VESSELS OF PAROTID GLAND

INTRODUCTION 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

Shape : inverted pyramidal

It has 4 surfaces:Superior surfaceSuperficial surfaceAnteriomedial surfacePosteriomedial surface

It tapers inferiorly to a blunt apex

It secretes saliva through Stenson Duct or Parotid Duct in the oral cavity

FACIAL NERVE 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

Next the nerve enters the parotid gland from its posteriomedial aspect and passes forwards and downwards behind the mandibular ramus

Within the substance of the gland it branches into: Temporofacial trunk

(superior)- runs upwards and divide intoo 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

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

oMarginal 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

oCervical 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

NERVE SUPPLY The parotid gland is supplied

by: PARASYMPATHETIC(SECRETOMO

TOR)SUPPLY-derived from auriculo temporal nerve Its stimulation produces watery

secretion SYMPATHETIC SUPPLY-derived

from the sympathetic plexus around the external carotid arteryStimulation produces thick sticky

secretion SENSORY SUPPLY- derived from

Auriculo-temporal nerveGreat auricular nerve

PREGANGLIONIC FIBRES OF PARASYMPATHETIC SUPPLY

POSTGANGLIONIC FIBRES OF PARASYMPATHETIC SUPPLY

Arise from the cells of the ganglion and pass through the auriculo-temporal nerve to supply the parotid gland

SYMPATHETIC SUPPLY

POSTGANGLIONIC FIBRES

FROM SYMPATHETIC PLEXUS AROUND

EXTERNAL CAROTID ARTERY

PREGANGLIONIC FIBRES

FROM LATERAL HORN OF T1

SPINAL SEGMENT

FROM SUPERIOR CERVICAL

SYMPATHETIC GANGLION

SYMPATHETIC SUPPLY

ARTERIAL SUPPLY 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

COMMON CAROTID ARTERY

EXTERNAL CAROTID ARTERY

MAXILLARY ARTERY SUPERFICIAL TEMPORAL ARTERY

TRANSVERSE FACIAL BRANCH

INTERNAL CAROTID ARTERY

VENOUS DRAINAGE Into retromandibular vein

and external jugular vein The retromandibular vein

is formed by the union of Maxillary veins Superficial Temporal veins

It lies superficial to external carotid artery

It descends in the parotid gland and emerges behind the apex of the gland

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

MAXILLARY VEIN

SUPERFICIAL TEMPORAL VEIN

RETROMANDIBULAR VEIN

ANTERIOR BRANCH

POSTERIOR BRANCH

POSTERIOR

AURICULAR VEIN

EXTERNAL JUGULAR VEIN

FACIAL VEIN

COMMON FACIAL VEIN

PATEY’S FACIOVENOUS PLANE

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.

CLINICAL

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

FREY’S SYNDROME