Infratemporal fossa and temporomandibular joint

Question 1

Contents of infratemporal fossa

Answer 1

• 4 muscles of mastication
• Mandibular nerve (V3) and its branches
• Otic ganglion
• Chorda tympani
• Maxillary artery and branches
• Pterygoid plexus of veins

Question 2

Osteology of infratemporal fossa

Answer 2

• The infra temporal fossa is below the zygomatic arch
• Superior boundary: greater wing of sphenoid, temporal bone, and zygomatic arch (zygomatic bone and temporal bone)
• Anterior boundary: zygomatic bone
• Posterior boundary: tempoal bone and styloid process
• Lateral boundary: zygomatic arch
• Medial boundary: maxilla and lateral pterygoid plate
• Parts of the mandible are within the infratemporal fossa

Question 3

Osteology of the temporal fossa

Answer 3

• Above the zygomatic arch

- Includes the frontal, parietal, greater wind of sphenoid, and temporal bones

Question 4

Osteology of the mandible

Answer 4

• Body: where molars are, contains the mental foramen for mental nerve (branch of inferior alveolar nerve of V3)
• Angle: roughly 90 degree turn of the mandible, connecting the ramus to the body
• Coronoid process: spike-like process anterior to the mandibular condyle (one attachment for temporal is muscle)
• Ramus: vertically running part of the mandible that contains the groove for mylohyoid nerve and the mandibular foramen (for inferior alveolar nerve), both on medial part of ramus
• Mandibular condyle: head of the mandible that inserts into TMJ
• Mental protuberance: most anterior part of mandible
• Mental tubercles: the two lateral sides of the mental protuberance

Question 5

Muscles of mastication 1

Answer 5

• Masseter: attaches to the zygomatic arch and angle of the mandible
• Functions in elevation of mandible and protrusion
• Temporalis: attaches to the coronoid process from aponeurosis w/ occipitalis
• Functions in elevation and retraction (horizontal fibers)
• Lateral pterygoid: runs from greater wing of sphenoid and lateral wall of the lateral pterygoid plate to the articular disc and head of mandible
• Functions in depression and protrusion

Question 6

Muscles of mastication 2

Answer 6

• Medial pterygoid: attaches to angle of mandible and medial wall of lateral pterygoid plate
• Functions in elevation and protrusion
• All of these muscles are innervated by branches of V3
• Both medial and lateral pterygoids are responsible for lateral movement of mandible
• The last 2 muscles of mastication are both innervated by mylohyoid nerve (branch of V3): mylohyoid and anterior belly of diagastric

Question 7

Temporomandibular joint

Answer 7

• Articulation of condyle of mandible w/ mandibular fossa and the articular tubercle (eminence) of temporal bone
• Within the TMJ there is a lower and upper synovial space bordering both the condyle and the mandibular fossa/articular tubercle
• Btwn the two synovial spaces there is an articular disc
• Upper synovial space responsible for gliding action
• Lower synovial space responsible for hinge action
• Lateral pterygoid muscle opens mouth by pulling condyle onto articular tubercle, followed by hinging action of condyle on the tubercle in lower joint space

Question 8

Dislocated jaw and TMJ d/o

Answer 8

• Dislocated jaw due to trauma or opening mouth too wide
• Condyles move anterior to articular tubercles and get caught there
• Must push up on anterior part of body and down on posterior part of body of the mandible
• TMJ d/o: pronounced joint noises associated w/ movement, pain upon palpation of muscles of TMJ, limited range of opening

Question 9

Mandibular nerve in infratemporal fossa

Answer 9

-V3 has 4 vertical branches in infra temporal fossa and one horizontal branch
-Vertical branches from anterior to posterior (A BLIMP):
Buccal nerve, Lingual nerve, Inferior alveolar nerve, Mylohyoid nerve
-Horizontal branch of V3: auriculotemporal nerve
-Mylohyoid nerve branches off the inferior alveolar nerve and runs in the groove of the mylohyoid, while the inferior alveolar nerve enters the mandibular canal w/ the inferior alveolar artery

Question 10

Components and innervation of V3 branches

Answer 10

• Buccal nerve (only SS) innervates mucosa of cheek and outer skin of the cheek
• Lingual nerve: SS to anterior 2/3rds of tongue, contains hitchhikers from VII via chord tympani (taste and para/pre)
• Inferior alveolar nerve: SS to lower teeth and skin of the chin (via mental nerve out of the mental foramen)
• Mylohyoid nerve: SM only to anterior belly of diagastric and mylohyoid muscles
• Mylohyoid nerve arose from inferior alveolar, so if inferior alveolar is tagged before the branching of mylohyoid it will have SM and SS
• Auriculotemporal nerve contains SS to skin of external ear/temple and hitchhikers from IX (para/post to parotid)

Question 11

Hitchhikers onto V3 1

Answer 11

• Para/pre from VII: cell bodies in superior salivatory nucleus (VII) run w/ VII thru internal auditory meatus and branch off in chord tympani w/in the middle ear
• Taste fibers of VII have the same path to chord tympani
• From the middle ear chord tympani reaches the infra temporal fossa and joins w/ the lingual nerve soon after it branches off of V3
• The para/pre use lingual nerve to reach the submandibular ganglion than run to submandibular gland, some also jump back onto the lingual nerve to reach sublingual gland
• Therefore depending on if the lingual nerve is tagger before or after the submandibular ganglion it will have either para/pre or para/post
• The taste fibers run w/ lingual nerve all the way to the tongue and supply taste to anterior 2/3rds of tongue

Question 12

Hitchhikers onto V3 2

Answer 12

• Para/pre from IX that reach the parotid gland via auriculotemporal have cell bodies in the inferior salivatory nucleus
• The axons run w/ IX thru the jugular foramen and then branch off IX to reach the middle ear as the tympanic nerve
• Tympanic nerve forms the tympanic plexus over the promontory of the middle ear
• This branch not only contains para/pre but also viscerosensory that will innervate all of the middle ear cavity
• The para/pre continue thru the middle ear as the lesser petrosal nerve and exit the middle ear thru foramen ovale

Question 13

Hitchhikers onto V3 3

Answer 13

• Right after foramen ovale the para/pre synapses on the otic ganglion that resides next to V3
• From the otic ganglion the para/post fibers join the auriculotemporal nerve which runs to the parotid gland and the para/post provides innervation there
• After the gland the auriculotemporal nerve continues, but only w/ SS to skin of ear and temple
• Therefore if the auriculotemporal nerve is tagged after the gland (cutaneous branch), it has only SS
• But if it is tagged before the gland is has SS and para/post

Question 14

Maxillary artery

Answer 14

• One of the terminal branches of the ECA, which terminate in infratemporal fossa
• The ECA terminates into the maxillary artery and the superficial temporal artery
• The maxillary gives off 2 important branches in the fossa: inferior alveolar artery and middle meningeal artery
• Inferior alveolar artery branches off inferiorly to run w/ inferior alveolar nerve thru mandibular foramen/canal
• Middle meningeal artery branches superiorly to run w/in a circle made by auriculotemporal nerve (perpendicular to each other) and up into the skull to supply the dura
• The three terminal branches of the maxillary artery: descending palatine, sphenopalatine, and infraorbital arteries