Infratemporal Fossa And Oral Cavity

Front 1

Boundaries of the Infratemporal Fossa

Back 1

Superior: infratemporal crest of the sphenoid bone

Anterior: posterior edge of the maxilla

Medial: pterygoid plates

Front 2

Osteological Features of the Sphenoid Bone

Back 2

Pterygoid fossa is between medial and lateral pterygoid plates.

Medial plate has a hamulus, muscle attachment point.

Front 3

Foramina in the infratemporal area

Back 3

- Foramen ovale (V3)
- Foramen spinosum (middle meningeal artery)
- Pterygomaxillary fissure

Front 4

Mandible osteology

Back 4

Body is horizontal, ramus is vertical, connecting portion is the angle.

Mandibular foramen and canal is on deep part of ramus. Lingular is bit that sticks out here.

Mental foramen allows the mental nerve (V3) to exit at chin level.

Condyle:
- head and neck

Fovea is line along condyly of mandible.

Mandible fits into notch on temporal bone.

Coronoid process is other protrusion (condyle is first) on ramus. Notch is between the two.

Mental spines are on interior surface (genial tubercles).

Mylohyoid line goes down inner body.

Front 5

Contents of the infratemporal fossa

Back 5

- Muscles of mastication
- Temporomandibular joint
- Maxillary artery
- Pterygoid plexus of veins
- Branches of V3 (auriculotemporal, lingal)
- Otic ganglion
- Chorda tympani (from CN VII)

Front 6

Muscles of mastication

Back 6

All associated with 1st pharyngeal arch (trigeminal).

All supplied by motor root of V3 (mandibular division).

Mandible moves at TMJ.

Front 7

Masseter

Back 7

Origin: zygomatic arch
Insertion: lateral side of mandibular ramus

Action:
- elevates the mandible (some protrusion)
- one side contracting produces ipsilateral (same side) excursion (lateral movement)

Front 8

Temporalis

Back 8

Origin: temporal fossa and fascia
Insertion: coronoid process

Action:
- elevates mandible
- posterior fibers retract the mandible
- one side contracting produces ipsilateral excursion (lateral movement)

Front 9

Medial Pterygoid (muscle)

Back 9

Origin: medial side of lateral pterygoid plate, pterygoid fossa

Insertion: internal surface of mandibular ramus

Action: elevates the mandible (some protrusion), one side contracting produces CONTRALATERAL excursion (opposite side).

Front 10

Lateral Pterygoid (muscle)

Back 10

Origin: superior head attaches to infratemporal crest of sphenoid and inferior head attaches lateral to lateral pterygoid plate.

Inserts: neck of condyle, pterygoid fovea (superior) and articular disc and capsule of TMJ.

Action:
Protrusion of the mandible, one side contracting produces CONTRALATERAL excursion.

Front 11

Temporamandibular Joint - TMJ

Back 11

Bony features:
- mandibular fossa (between condyle and head)
- articular tubercle
- condyle of mandible

Synovial joint:
- articular cartilage (fibrocartilage)
- capsule
- intra-articular disc (divides joint ino upper and lower cavities)

Front 12

Articular Disc

Back 12

Attached around its circumference to the joint capsule

Attached firmly to the neck of the condyle via the joint capsule (assures disc and condyle move together, attached anteriorly to lateral pterygoid muscle).

Disc is thinner centrally (bi-concave shape).

Front 13

Resting Position of the Mandible

Back 13

At rest, mandibular condyle sits inferior to mandibular fossa of temporal bone.

Teeth are slightly separated, relaxed.

Front 14

Movement at the TMJ

Back 14

Sliding is translation. Lets you protract and retract the jaw. Upper joint space.

Hinge type motion lets you elevate and depress, lower joint space.

Front 15

Opening the mouth

Back 15

Suprahyoid muscles initiate movement (depression of mandible, lower joint space)

To fully open mouth, need to protrude (condyle and disc need to slide anteriorly onto articular tubercle).
Lateral pterygoids are primary movers.

With mouth widely open, condyle rests under peak of articular tubercle.

To close mouth, elevate and retract mandibile. (masseter, temporalis, medial pterygoid muscle all pull condyle back into mandibular fossa).

Front 16

Action of Lateral Pterygoid

Back 16

Lateral pterygoid muscle is primary protractor of mandible.

Front 17

Maxillary Artery

Back 17

A terminal branch of the external carotid, travels through infratemporal fossa and into pterygopalatine fossa:
- runs deep to ramus of mandible
- supplied all teeth plus palate, nasal cavity, muscles of mastication, bones, midface
- main artery of deep facial structures

Front 18

Major Branches of Maxillary Artery

Back 18

1) Inferior alveolar artery: travels inside mandibular canal to mandibular teeth, and feeds mental artery to chin. Branches to muscles of mastication

2) Superior alveolar arteries: within maxilla, to maxillary teeth

3) Infraorbital artery, to midface

4) Middle meningeal artery: to skull bones, meninges. Goes through foramen spinosum.

5) Greater and lesser palatine arteries: to palate

6) Sphenopalatine artery: gives off nasopalatine artery, to nasal cavity and anterior hard palate

Front 19

Pterygoid Plexus of Veins

Back 19

On surface of pterygoid muscles, drains into infratemporal region.

Connects to:
- facial veins
- maxillary veins
- jugular veins
- deep connections to cavernous sinus

Front 20

Cavernous Sinus Thrombosis (clinic)

Back 20

Connections between cavernous sinus:
- facial veins
- pterygoid veins
- ophtalmic veins

Infections on face or of dental region can spread via veins to cavernous sinus

Front 21

Motor Branches of V3 (mandibular division)

Back 21

V3 exits via foramen ovale.

Sends branchial motor branches to all muscles of mastication, plus:

- motor branches to other muscles associated with 1st pharyngeal arch (mylohyoid nerve mylohyoid and anterior digastric), tensor tympani and tensor veli palatini

Front 22

Sensory branches of V3

Back 22

Auriculotemporal nerve:
- sensory from TMJ, side of face
- SPLITS AROUND middle meningeal artery
- also carries postganglionic parasympathetic from the otic ganglion (CN IX) to parotid gland

Buccal nerve (long buccal), sensory from the cheek. Passes between the heads of lateral pterygoid.

Front 23

Sensory branches of V3: lingual nerve

Back 23

Passes between pterygoid muscles, carries general sensation from anterior 2/3 of tongue, floor of the mouth and lingual gingiva
Joined by the chorda tympani (CN VII).

Front 24

Sensory branches of V3: inferior alveolar nerve

Back 24

General sensation from mandibular teeth.

Passes through mandibular foramen and canal (passes between ramus and sphenomandibular ligament, mylohyoid nerve splits off here).

Mental nerve (carrying sensation from chin and lower lip), branches off through mental foramen.

Front 25

Oral Cavity

Back 25

Internal to teeth and dental arches, extends to oropharynx.

Most prominent feature is tongue. Connected to floor of mouth by frenulum.

Muscular floor of mouth is mylohyoid.

Front 26

Mylohyoid Muscle

Back 26

Originates on mylohyoid line of mandible.

Inserts on hyoid bone.

Acts to elevate hyoid and floor of mouth. Can also help depress mandible.

Front 27

Submandibular and Sublingual Glands

Back 27

Sublingual gland:
- Empties through a series of small ducts along floor of mouth.

Submandibular gland:
- wraps around posterior border of mylohyoid. Has long duct.

Front 28

Submandibular Duct

Back 28

Travels along floor of the mouth. Crosses over lingual nerve. Empties onto sublingual caruncle (papilla) at base of frenulum.

Front 29

Parasympathetic Supply to Salivary Glands

Back 29

Preganglionic parasymp fibers from superior salivary nucleus of CN VII (facial) travel with the CHORDA TYMPANI branch.

Chorda tympani hitchhikes on lingual nerve of V3. Synapses at submandibular ganglion. Postganglionic fibers go to submandibular or sublingual gland.

Front 30

Chorda Tympani Nerve

Back 30

Crosses middle ear cavity, exits into infratemporal fossa through the petrotympanic fissure. Hitchhikes onto lingual nerve of V3 to enter oral cavity.

Front 31

Tongue

Back 31

Base of tongue is oropharynx. Anterior 2/3 of tongue are in oral cavity.
Tip = apex.

Underside is ventral, upper surface is dorsum.

Front 32

Dorsum of tongue

Back 32

Terminal sulcus:
separates anterior 2/3 from posterior 1/3. V shaped groove with foramen cecum at apex (origin of thyroglossal duct of thyroid gland).

Lingal papillae are raised mucosal projections of mucosa associated with the taste buds.

Front 33

Base of tongue

Back 33

Posterior 1/3 of tongue.

From terminal sulcus to epiglottis.

Valleculae: depressions between tongue and epiglottis outlined by glossoepiglottic folds (LINGUAL TONSILS ARE HERE!)

Front 34

Deep lingual veins (clinic)

Back 34

Thin mucosa covering deep lingual veins facilitating absorption of sublingually administered medications.

Front 35

Muscles of tongue

Back 35

All tongue muscles are paired.

Intrinsic muscles: origin and insertion in tongue, named by fiber direction and change the shape of tongue and produce complex movements.

Extrinsic muscles of tongue have origin outside tongue. Three pairs:
1) Hyoglossus goes from hyoid bone to tongue, depressor
2) Styloglossus originates from styloid process of temporal bone, retracts tongue
3) Genioglossus: originates from genial tubercles (mental spines) on mandible and protrude tongue.

Front 36

Hypoglossal Nerve: CN XII

Back 36

Somatic motor:
- motor supply to all intrinsic AND extrinsic tongue muscles

Exits via hypoglossal canal, travels across neck. Inferior to digastric tendon, lateral to carotids. Enters base of tongue above hyoglossus muscle.

Front 37

Sensory Nerve Supply of Tongue

Back 37

General Sensory:
- anterior 2/3 by lingual nerve of V3 (mandibular)
- posterior 1/3 by lingal branch of glossopharyngeal (CN IX)

Taste (special):
- anterior 2/3 by facial nerve via chorda tympani
- posterior 1/3 via CN IX
- Epiglottis and valleculae via vagus nerve (CN X).