Parotid gland
Introduction
• Lies in front and below the ear
• Largest of three pairs of salivary glands
• Composed almost entirely of serous alveoli
• Lobulated, yellowish brown gland
• Weight -25 g
• Development- Ectodermal lining of primitive mouth at its lateral angle
Location
• Lies in pyramidal fossa- posterior to ramus of the mandible- retromandibular fossa
(parotid bed)
Boundaries of parotid bed
• Anteriorly- posterior border of ramus of mandible with masseter and Medial
pterygoid
• Posteriorly- mastoid process with sternocleidomastoid and posterior belly of digastric
• Superiorly- external acoustic meatus and posterior part of temporomandibular joint
• Medially- styloid process with styloglossus, stylohyoid and stylopharyngeus
Extent
• Parotid gland- not confined only to parotid bed but extends beyond it
• Above- exteds into external auditoy meatus anb below-into upper part of carotid
triangle
• Medially- extends into styloid process(close to side wall of pharynx)
• Posteriorly-overlaps SCM muscle
• anteriorly-extends into masseter muscle and part of this forward extension -detached
from rest of gland -accessory parotid gland - lies between zygomatic arch above and
the parotid duct below - ducts from accessory gland open into parotid duct
Parotid capsule(parotid sheath)
False capsule
• Formed by investing layer of deep cervical fascia- fascia splits to enclose gland
between angle of the mandible and mastoid process
• Superficial lamina – thick, strong, unyielding and adherent to gland- blends with
epimysium of masseter to form thick parotidomasseteric fascia -attached above to
zygomatic arch
• Deep lamina- thin -attached to tympanic plate and styloid process of temporal bone-
thickened to form stylomandibular ligament - separates parotid gland from
submandibular gland
True capsule-condensation of fibrous stroma of gland
External features
Resembles three sides pyramid
1. Apex -directed upwards
2. Four surfaces- Superior(base), Anteromedial, posteromedial and Superficial/lateral
3. Three borders- anterior,posterior and medial
Apex
• Overlaps posterior belly of digastric
• Structures emerging
a. Cervical branch of facial nerve
b. Anterior and posterior division of retromandibular vein
Superior surface or base
• Related to external acoustic meatus and posterior aspect of temporomandibular joint
• Structures emerging
a. Superficial temporal vessels
b. Auriculotemporal nerve.
Superficial surface
• Largest surface
• From superficial to deep
a. Skin
b. Superficial fascia - greater auricular nerve, superficial parotid (preauricular)
lymph nodes and platysma
c. Parotid fascia(investing layer of deep cervical fascia)
d. Deep parotid lymph nodes Save to collection
Anteromedial surface
• Deeply grooved by posterior border of ramus of mandible
• Related to
a. Masseter
b. Medial pterygoid
c. Posterior border of ramus of mandible
d. Lateral aspect of temporomandibular joint
e. Branches of facial nerve emerge on face underneath this surface
Posteromedial surface
• Related to mastoid and styloid processes and their covering muscles
a. Mastoid process, sternocleidomastoid, and posterior belly of digastric
b. Styloid process and styloid group of muscles
c. Styloid process and its muscles- separate gland from carotid Sheath- internal
carotid artery, internal jugular vein, and last four cranial nerves
d. Between styloid process and mastoid process-Facial nerve trunk emerge and
enter in its upper part
e. External carotid artery-enter in its lower part.
Anterior border
• separates superficial surface from anteromedial surface
• Structures emerging(above downwards)
a. Temporal branch of facial nerve
b. Zygomatic branch of facial nerve
c. Transverse facial vessels
d. Upper buccal branch of facial nerve
e. Parotid duct
f. Lower buccal branch of facial nerve
g. Marginal mandibular branch of facial nerve
Posterior border
• Separates superficial surface from posteromedial surface
• Structures emerging
a. Posterior auricular vessels
b. Posterior auricular branch of the facial nerve.
Medial border
• Separates anteromedial surface from posteromedial surface
• Related to lateral wall of pharynx
Structures present within parotid gland
• Three main structures traverse the gland and branch within it
• From superficial to deep
1. Facial nerve
2. Retromandibular vein
3. External carotid artery
Facial nerve
• Most superficial
• Enters gland through upper part of posteromedial surface and divides into five
terminal branches- Temporal, zygomatic, buccal(upper and lower), marginal
mandibular and cervical within the gland
• Branches -run horizontally and leave gland through anteromedial surface and
appear on face underneath its anterior border
• Five terminal branches of facial nerve- radiate like goose-foot through anterior
border of gland- pes anserinus
Retromandibular vein
• Occupies intermediate zone of gland
• Formation- union of superficial temporal and maxillary veins
• Ends by dividing into anterior and posterior divisions
• Anterior division joins facial vein to form common facial vein
• Posterior division joins posterior auricular vein to form external jugular vein
External carotid artery
• Occupies deep zone of gland
• Enters the gland by piercing lower part of posteromedial surface
• Within the gland behind neck of mandible- divides into superficial temporal and
maxillary arteries
• Transverse facial artery- branch of superficial temporal artery- emerges through
anterior border of gland
Surgical lobes of parotid gland and Patey’s facio-venous plane
• Divided into two lobes/parts- large superficial lobe and small deep lobe-lobes
connected with each other by isthmus of glandular tissue-gland appears H
shaped
• Lobes are separated from each other by facial nerve and its branches- pass
forward through isthmus
• Plane between superficial and deep lobes of parotid gland - branches of facial
nerve and retromandibular vein lie -Patey’s as facio-venous plane - helps
surgeons to remove parotid tumour without damaging nerve
Parotid duct(Stenson’s duct)
• Length- 5 cm long
• Emerges from middle of anterior border of gland and opens into vestibule of mouth
opposite crown of upper second molar tooth
• Course
o After emerging from gland- it runs forward over masseter between upper and
lower buccal branches of facial nerve
o At the anterior border of masseter-it turns inwards almost at 90 degrees (first
bend) -pierces buccal pad of fat, buccopharyngeal fascia, and buccinator
muscle
o After piercing buccinator muscle- it runs forwards (second bend) for 1 cm
between buccinator and buccal mucosa
o Finally- duct turns medially (third bend) and opens into vestibule of mouth
opposite crown of upper second molar teeth
o Tortuous course of duct -provides valve-like mechanism to prevent inflation of
duct system of parotid gland during excessive blowing of mouth as in trumpet
blowing
Nerve supply
Supplied by parasympathetic, sympathetic, and sensory fibres
Parasympathetic (Secretomotor pathway)
• Provided through auriculotemporal nerve
• Stimulation of parasympathetic supply produces watery secretion
• Preganglionic fibres arise from
inferior salivatory nucleus in medulla glossopharyngeal nerve tympanic
branch of glossopharyngeal (Jacobson’s nerve) tympanic plexus lesser
petrosal nerve relay into otic ganglion
• Postganglionic fibres
Arise from cells of ganglion auriculotemporal nerve parotid gland
Sympathetic supply
• Vasomotor and their stimulation produces thick sticky secretion
• Preganglionic fibres
Lateral horn of T1 spinal segment Relay in superior cervical sympathetic
ganglion
• Post ganglionic fibres
Sympathetic plexus around external carotid artery pass through otic ganglion
with out relay and supplies parotid gland through auriculotemporal nerve
Sensory supply- Auriculotemporal nerve and Great auricular nerve (C2 and C3)
Vascular supply
• Derived from external carotid and superficial temporal arteries
• Venous drainage -into retromandibular and external jugular veins
Lymphatic drainage
• Drain into superficial and deep parotid lymph nodes - drain into deep cervical lymph
nodes
• Superficial nodes lie in superficial fascia over parotid gland
• Deep nodes -lie deep to parotid capsule
Clinical Anatomy
Infection of the parotid gland
• Mumps- commonly infected by mumps virus- inflammation and swelling of gland
• Very painful- due to unyielding nature of parotid capsule and stimulation of
branches of great auricular nerve
• Pain- exacerbated at meal time
Mixed parotid tumour(pleomorphic adenoma)
• Slow-growing lobulated painless tumour of large superficial part of parotid gland-
mixed histological appearance
• After many years of slow benign growth- undergo malignant change
Parotidectomy
• surgical removal of tumour in superficial lobe -superficial parotidectomy
• Surgical removal of tumour in deep lobe or both in superficial and deep lobes - total
parotidectomy
Parotid sialogram
• Parotid duct can be demonstrated radiologically - injecting radiopaque dye through
mouth of parotid duct
Sialolithiasis- Stone in the parotid gland and duct
Frey syndrome
• Sometimes penetrating wounds of parotid gland -may damage auriculotemporal and
great auricular nerves
• Auriculotemporal nerve contains parasympathetic (secretomotor), sensory, and
sympathetic fibres
• Great auricular nerve contains sensory and sudomotor fibres
• When these nerves are cut- during regeneration - secretomotor fibres (salivation) i.e
auriculotemporal nerve grow into great auricular nerve(sensory) and
sympathetic(vasomotor) fibres- Thus stimulus intended for salivation evokes
cutaneous hyperaesthesia, sweating, and flushing
• When a person eats - ipsilateral cheek (parotid region) becomes red, hot, and painful
associated with beads of perspiration (gustatory sweating)
• When a person shaves- cutaneous hyperesthesia in front of ear
