1. Parotid Region and Muscles of Mastication Parotid Gland
Shape:
Irregular pyramid with an upper end, anterior end and a lower end
Has 3 surfaces: lateral (superficial), anteromedial and posteromedial
External
acoustic meatus
sternomastoid
Ramus of
mandible
sternomastoid
Masseter
muscle
Position:
Wedged between the ramus of mandible and the sternomastoid
Its upper end fits into the external acoustic meatus
Its lower end reaches down to the angle of the mandible
Overlaps the masseter ms (ant) and the sternomastoid (post)
Accessory parotid gland
A small semi-detached part of the gland lies on the masseter between the zygomatic arch and parotid duct
Anteromedial
surface
Posteromedial
Lateral surface

2. Capsule:
The gland is ensheathed by a capsule derived from the deep cervical fascia
Attached superiorly to the zygomatic arch
Deeply, it is attached to the angle of mandible and styloid process, forming the stylomandibular ligament
The stylomandibular ligament separates the parotid gland from the submandibular gland
External
acoustic meatus
Z y g o m a t i c a r c h
Mastoid
process
Styloid process
Stylo-mandibular
ligament
Stylo-mandibular
ligament
Medial veiw
Lateral veiw

3. Relations Lateral surface: Anteromedial surface:
Skin, superficial fascia, platysma
Great auricular nerve
Preauricular lymph nodes
TMJ
Ramus
Anteromedial surface:
Posterior border of the ramus of mandible
Temporomandibular joint (TMJ)
Insertion of medial pterygoid muscle (on the inner surface of the ramus)
Masseter muscle (on the outer surface of the ramus)

4. Sternomastoid & posterior
Posteromedial surface:
Mastoid process, sternomastoid ms, and posterior belly of digastric ms.
Styloid process and muscles attached to it
The styloid process separates the gland from the carotid sheath and its contents (ICA & IJV)
Terminal part of ECA
The medial border of the gland is in contact with the lateral wall of pharynx
Styloid process
Sternomastoid & posterior
belly of digastric
Upper end:
Fits below the external acoustic meatus
ECA
ICA & IJV

5. Structures within the substance of the parotid gland
Main structures:
Terminal part of ECA: deep in position
Retromandibular V: intermediate in position
Facial N: superficial in position
Auriculotemporal
nerve
Superficial temporal vessels
Parotid
gland
Terminal branches
of facial nerve
Posterior auricular vein
Posterior branch of
retromandibular v.
External jugular vien
Common
facial vein
Anterior branch of retromandibular v.
IJV

6. How structures enter and leave the gland
ECA, enters the gland through its posteromedial surface and divides into superficial temporal and maxillary arteries
Superficial temporal artery: leaves the gland through its upper end
Maxillary artery: leaves the gland through its anteromedial surface
Maxillary vein: enters the gland through the anteromedial surface
Superficial temporal vein: enters the gland through the upper end
Retromandibular vein, formed inside the gland by union of maxillary and superficial temporal veins
It divides into anterior and posterior divisions, which leave the gland through its lower end
The posterior division joins the posterior auricular vein to form the external jugular vein
The anterior division joins the anterior facial vein to form the common facial vein
Facial nerve, comes out of stylomastoid foramen and enters the gland through its posteromedial surface
It divides into 5 terminal branches within the substance of the gland
Branches of facial nerve: leave through the upper end (temporal branches), anteromedial surface (zygomatic and buccal branches) and lower end (marginal mandibular and cervical branches)
Auriculotemporal nerve: enters through the anteromedial surface and leaves through the upper end

7. Parotid duct: Surface anatomy of the parotid duct Two inches long
Arises from the anterior border of the gland
Runs on the masseter below the zygomatic arch and accessory parotid gland
It runs between the upper and lower buccal branches of facial nerve
The buccal branch of mandibular nerve runs below the duct
It receives a small duct from the accessory parotid duct
At the anterior border of masseter, it turns medially piercing the buccal pad of fat, buccopharyngeal fascia, the buccinator muscle and the buccal mucosa
Opens into the vestibule of the mouth opposite the upper second molar tooth
Parotid duct
Opening of
parotid duct
Buccinator
Buccal pad of fat
Masseter
Surface anatomy of the parotid duct
Represented by the middle third of a line between the lower border of the tragus and a point midway between the ala of the nose and the red margin of upper lip
The duct can be palpated on the anterior border of masseter on contracting the muscle

8. Nerve supply: Arterial supply: ECA
Lesser petrosal
nerve
Arterial supply: ECA
Venous drainage: Retromandibular Vein
Lymph drainage: Preauricular lymph nodes
Tympanic
plexus
CN IX
Inferior salivary
nucleus
Tympanic branch
of CN IX
Otic ganglion
Nerve supply:
Sensory: auriculotemporal nerve
Sympathetic: plexus around ECA
Parasympathetic: postganglionic fibres from the otic ganglion carried by the auriculotemporal nerve
Auriculotemporal
nerve
ICA
The preganglionic fibres arise from the inferior salivary nucleus in the brain stem, run with CN IX, then through its tympanic branch to join the tympanic plexus, fibres are then carried by the lesser petrosal nerve which leaves through the foramen ovale and terminates in the otic ganglion

9. Temporal fossa A shallow fossa on the side of the head Boundaries:
Temporal lines
A shallow fossa on the side of the head
Boundaries:
Zygomatic arch, below
Temporal lines, above
Frontozygomatic process, anteriorly
Supramastoid crest, posteriorly
Temporal
fossa
Contents:
Temporalis muscle, covered by temporal fascia
Deep temporal nerves and vessels
Auriculotemporal nerve
Superficial temporal artery
Zygomatic
arch
Deep temporal
nerves
T e m p o r a l i s
M u s c l e
Auriculotemporal
nerve

10. Muscles of Mastication
Temporalis ms.
Origin: floor of temporal fossa & inner surface of temporal fascia
Insertion: coronoid process of the mandible
Action:
Elevation of the mandible (anterior and middle fibers)
Retraction of the protruded mandible (posterior fibers)
Nerve supply: deep temporal nerves
(anterior division of mandibular nerve)
Temporalis
Muscle
Masseter ms.
Origin: lower border and inner surface of zygomatic arch
Insertion: outer surface of the ramus of mandible
Action: elevation of the mandible
Nerve supply: nerve to masseter (anterior division of mandibular nerve)
Coronoid process
of mandible
Temporal fascia
Temporal fascia
Covers the temporal fossa and temporalis muscle
Superiorly, it is attached superiorly to the superior temporal line
Inferiorly, it is attached to upper border of zygomatic arch
Its deep surface gives origin to temporalis muscle
Temporalis
Masseter

11. Superficial & deep heads
Upper & lower heads
of lateral pterygoid
Lateral pterygoid ms.
Origin: by two heads
upper head: infratemporal crest and infratemporal surface of greater wing of sphenoid
lower head: lateral surface of lateral pterygoid plate
Insertion:
pterygoid fovea (front of the neck of mandible)
capsule and articular disc of temporomandibular joint
Action:
protrusion of the mandible
pulls the head of mandible forwards (during opening the mouth)
side to side movement of the mandible (chewing)
(acting with medial pterygoid, alternately with the muscles of the contralateral side)
Nerve supply: nerve to lateral pterygoid
(anterior division of mandibular n)
Articular disc
of TMJ
Superficial & deep heads
of medial pterygoid
Lateral
pterygoid
TMJ
Medial pterygoid ms.
Origin: by two heads
superficial head: tuberosity of the maxilla
deep head: medial surface of lateral pterygoid plate
Insertion: inner surface of the ramus of mandible
Action:
Elevation & protrusion of the mandible
side to side movement (chewing)
Nerve supply: nerve to medial pteryoid (trunk of mandibular n)
medial
pterygoid