Parotid, Temporal, Infratemporal Fossae, and TMJ

Parotid region

• Posterolateral part of the facial region

• Includes:

  • parotid gland and duct

  • parotid plexus of the facial nerve (CN VII)

  • retromandibular vein

  • external carotid artery

  • masseter muscle

Zygomatic arch

Superior boundary of the parotid region

External ear, anterior border of SCM

Posterior boundary of the parotid region

Ramus of the mandible

Medial boundary of the parotid region

Anterior border of masseter

Anterior boundary of the parotid region

Angle and inferior border of mandible

Inferior boundary of the parotid region

Parotid gland

• Largest salivary gland

• approx. weight: 15g

• enclosed within a parotid sheath

• occupies the parotid bed

• irregularly shaped/triangular

Irregularly shaped/triangular

Shape of parotid gland

Anteroinferior to the EAM, between ramus and mastoid process/SCM

Location of the parotid gland

Anterior to EAM

The base of the parotid gland is located _____

Posterior to the angle of the mandible

The apex of the parotid gland is located _____

Parotid sheath

• Parotid fascia/fascial sheath

• Tough, unyielding fascial capsule

• Continuation of cervical fascia

• Attaches to the deep surface of the ramus and angle of the mandible

• Encloses the parotid space (entirely closed)

cervical fascia

The parotid sheath is a continuation of the _____

Stensen’s duct

Another name for parotid duct

Parotid duct

• Passes horizontally from the anterior edge of the gland

• Pierces the buccinator and enters the oral cavity through a small cavity opposite the 2nd maxillary molars (17 or 27)

Buccinator

What muscle does the parotid duct pierce?

2nd maxillary molars

The parotid duct pierces the buccinator and enters the oral cavity through a small cavity opposite the _____

Anterior, posterior, medial

Borders of the parotid gland

Superior, superficial, anteromedial, posteromedial

Surfaces of the parotid gland

Apex of the parotid gland

Contains:

• Cervical branch of facial nerve (CN VII)

• Divisions of retromandibular veins

Base of the parotid gland

Contains:

• EAM

• Superficial temporal vessels

• Auriculotemporal nerve

• Facial nerve

• Facial nerve

• Retromandibular vein

• External carotid artery

Structures passing through the parotid gland

Retromandibular vein

• Drains structure of face

• Drainage of parotid gland

• Deep

• Auriculotemporal nerve (general pain sensation)

• Greater auricular nerve (branch of cervical plexus)

Sensory innervation of parotid gland

Glossopharyngeal nerve (CN IX)

Parasympathetic innervation of the parotid gland

Secretion of thin, watery saliva

Parasympathetic stimulation of parotid gland

CN IX → tympanic plexus (in middle ear) → lesser petrosal nerve → otic ganglion → post-ganglionic parasympathetics (auriculotemporal nerve) → parotid gland

Parasympathetic pathway of the parotid gland

Carotid plexus

Sympathetic innervation of the parotid gland

Reduce saliva secretion

Sympathetic stimulation of parotid gland

• Posterior auricular artery

• Superficial temporal artery

Blood supply of the parotid gland

• Parotid node

• Jugulodigastric node

Lymphatic drainage of the parotid gland

Temporal region

Lateral area of the scalp and the deeper soft tissues overlying the temporal fossa of the cranium, superior to the zygomatic arch

Temporal fossa

• Lateral depression of the skull

• Occupied by the temporalis muscle

• Boundaries:

  • Post & sup: temporal lines

  • Ant: frontal and zygomatic bones

  • Lat: zygomatic arch

  • Inf: infratemporal crest

Temporalis

• Large, fan-shaped muscle

• Arises from the bony floor and overlying temporal fascia

• Attaches to the skull between the superior and inferior temporal lines

Temporal fascia

• Forms the roof of the temporal fossa

• Inferiorly splits into 2 layers

• Tethers the zygomatic arch superiorly

• Resists downward pull when masseter contracts

Temporalis fascia

Superior attachment of temporalis

Floor of temporal fossa, deep surface of temporal fascia

Proximal attachment of temporalis

Coronoid process, anterior border of ramus of mandible

Inferior attachment of temporalis

Deep temporal branches of CN V3

Innervation of temporalis

• Elevation of mandible - anterior & superior fibers

• Retraction - posterior/horizontal fibers

Actions of temporalis

Infratemporal fossa

•  Irregularly-shaped space deep and inferior to the zygomatic arch, deep to the ramus of the mandible, and posterior to the maxilla

• Communicates with temporal fossa

• Boundaries:

  • Lat: ramus of mandible

  • Med: lateral pterygoid plate

  • Ant: post. aspect of maxilla

  • Post: tympanic plate and mastoid and styloid processes of the temporal bone

  • Sup: inferior (infratemporal) surface of the greater wing of sphenoid

  • Inf: where the med pterygoid muscle attaches to the mandible near its angle (imaginary)

Lateral pterygoid muscle

All muscles of mastication elevate the mandible EXCEPT the _____

• Inferior part of temporalis

• Lateral and medial pterygoid muscles

• Maxillary artery

• Pterygoid venous plexus

• Mandibular, inferior alveolar, lingual, buccal, chorda tympani nerves

• Otic ganglion

Contents of infratemporal fossa

• Masseter

• Temporalis

• Lat pterygoid

• Med pterygoid

Muscles of mastication

Lateral and medial pterygoid muscles

Quadrangular, 2-headed muscles of mastication

• Deep auricular

• Anterior tympanic

• Middle meningeal

• Accessory meningeal

• Inferior alveolar

Branches of the 1st part of the maxillary artery

• Branches to muscles of mastication

• Buccal artery

Branches of the 2nd part of the maxillary artery

• Infraorbital

• Descending palatine

• Artery of pterygoid canal

• Sphenopalatine

• Anterior, middle, posterior superior alveolar

• Pharyngeal

• Artery of pterygoid canal

Branches of the 3rd part of the maxillary artery

Deep auricular artery

• Lies within parotid gland

• Supplies:

  • TMJ

  • EAM

  • outer surface of ear drum

Anterior tympanic artery

• Arises within parotid gland

• Supplies tympanic cavity and inner surface of ear drum

Middle meningeal artery

• Enters cranial cavity via foramen spinosum

• Supplies skull and dura mater

Foramen spinosum

The middle meningeal artery enters the cranial cavity via _____

Accessory meningeal artery

• Enters cranial cavity via foramen ovale

• Supplies semilunar ganglion (CN V) and dura mater

Foramen ovale

The accessory meningeal artery enters the cranial cavity via _____

Inferior alveolar artery

• Enters mandibular foramen

• Supplies lower teeth and gums

• Passes through mental foramen and becomes mental artery

Mandibular foramen

The inferior alveolar artery enters _____

mental foramen ; mental artery

The inferior alveolar artery passes through _____ and becomes _____

Posterior superior alveolar artery

• Runs with superior alveolar nerve (CN V2)

• Supplies upper molars and premolars

Infraorbital artery

• Enters orbit via inferior orbital fissure

• Runs with infraorbital nerve

• Supplies lower eyelid, side of nose, upper lip, oral mucosa

• Gives rise to anterior and middle superior alveolar arteries

Infraorbital artery

Which artery gives rise to anterior and middle superior alveolar arteries

Inferior orbital fissure

The infraorbital artery enters orbit via _____

Descending palatine artery

• Supplies soft and hard palates

• Terminal branch

Artery of pterygoid canal

Supplies pharynx and auditory tube

Pterygoid venous plexus

What is the venous counterpart of maxillary arteries?

Chorda tympani

Provides taste sensation from anterior 2/3 of tongue

Temporomandibular joint

• A modified hinge type of synovial joint, permitting translation and a small degree of pivoting in addition to elevation and depression movements

• Ginglymoarthrodial joint

  • ginglymus — hinge

  • arthrodial — gliding

• An example of diarthrosis (freely movable)

• The only mobile joint of the skull

Fibrocartilage

Articular surface of TMJ is covered by _____

Occlusal contact of teeth

Rigid endpoint of closure of TMJ

TMJ

Last joint to start to develop

• Articular tubercle of temporal bone

• Mandibular fossa

• Condyloid process of mandible

• Articular disc

• Superior articular cavity

• Inferior articular cavity

Parts of the TMJ

Mandibular fossa

Where condylar head is articulated (TMJ)

Fibrous capsule

▪ Capsule that encloses the TMJ

▪ Attached at the borders of the articulating surfaces of the mandibular fossa and eminence of the temporal bone and to the neck of the mandible

Articular disc

▪ Fibrocartilaginous disc dividing joint cavity in upper and lower compartments

▪ Sagittal section: a thin intermediate zone with thickened anterior and posterior bands

▪ Posteriorly: attached to a region of loose vascular nervous tissue

Lateral ligament

Ligament of TMJ

• Formed by the thickened part of the joint capsule

• Attached above the articular tubercle

• Extends downwards and backwards at angle of 45º to the horizontal

• Strengthens the joint laterally

Sphenomandibular ligament

• A flat, thin band that descends from the spine of the sphenoid

• Runs from the spine of the sphenoid to the lingula of the mandible

• Widens at the lingula of the mandibular foramen

• Medial to and normally separate from capsule

• Primary passive support of the mandible

Stylomandibular ligament

A thickened band of deep cervical fascia that stretches from apex and adjacent anterior aspect of the styloid process to the angle and posterior border of the mandible

• Superficial temporal artery

• Maxillary artery

Blood supply of TMJ

• Masseteric

• Auriculotemporal nerves

Nerve supply of TMJ

Rotational/hinge movement

TMJ movement in the first 20-25 mm of mouth opening

Translational movement

TMJ movement when mouth is excessively opened (disc glides to articular tubercle)

Elevation

Action of:

• Temporalis

• Masseter

• Medial pterygoid

Depression

Action of:

• Lateral pterygoid

• Suprahyoid

• Infrahyoid

Protrusion

Action of:

• Lateral pterygoid

• Masseter

• Medial pterygoid

Retrusion

Action of:

• Temporalis (posterior oblique and near horizontal fibers)

• Masseter

Lateral movements

Action of:

• Temporalis of same side

• Pterygoids of opposite side

• Masseter

Symmetrical jaw opening

• Start: Each mandibular condyle rotates in the lower joint compartment.

• After a few degrees of opening: The condyle continues rotating; both slide forward

50-60 mm

Maximum mouth opening

Eccentric jaw opening

• Condyle on the non-working side slide back and forth during lateral movements.

• Temporomandibular and sphenomandibular ligament keep condyle firmly against articular eminence

Temporomandibular and sphenomandibular ligament

They keep condyle firmly against articular eminence

Eccentric and symmetric jaw closing

▪ Jaw closing muscles

▪ Joint tissues compressed, ligaments shortened

▪ Non-working condyle moves further