Infratemporal Fossa

Question 1

Muscles of mastication (what are they, what are they derived from embryologically, and what is their innervation)

Answer 1

All the muscle of mastication are innervated by CN V3 - SVE and include the lat/med pterygoids, masseter, and temporalis.

They are all derived from the 1st pharyngeal arch.

Question 2

Temporalis (Action and innervation)

Answer 2

Action - closes and retracts jaw

Innervation - ant/post deep temporal nn.

Question 3

What is the temporobuccinator band?

Answer 3

A dense CT band which runs from the temporalis to the buccinator to draw the buccinator away from the teeth

Question 4

Masseter (Aciton and innervation)

Answer 4

Action - closes and assists with protrusion of the jaw

Innervation - masseteric branches of V3

Question 5

Medial Pterygoid (Action and innervation)

Answer 5

Action - closes jaw and asssists in protrusion and pivot

Innervation - medial pterygoid branches of V3

Question 6

Lateral Pterygoid (Action and innervation)

Answer 6

Action - Performs protrusion and pivot

Innervation - lateral pterygoid branches of V3

Question 7

What components make up the temporomandibular joint?

Answer 7

Articulation of the mandibular condyle with mandibular fossa and articular tubercle of temporal bone

Question 8

What is the action at TMJ during motion?

Answer 8

When the mouth opens the mandibular condyle slides forward in the mandibular fossa to contact the articular tubercle.

Question 9

Describe the TMJ capsule

Answer 9

Separated into two capsules by a dense articular disc. The capsule is loose above the disc and tight below.

Question 10

Describe the three ligaments of the TMJ

Answer 10

Lateral ligament of TMJ - thickening of the joint capsule which prevents posterior dislocation

Stylomandibular ligament - a thickening of the parotid fascia which attaches the styloid process to the angle of the mandible. This is a weak ligament.

Sphenomandibular ligament - runs from the spine of the sphenoid to the dingula of the mandible. This is a strong ligament

Question 11

Describe the functions of the lower and upper protions of the TMJ

Answer 11

The lower portion undergoes pivoting to allow for side to side movement while chewing.

The upper portion allows for gliding allowing protrusion/retrusion and elevation/depression.

Question 12

How do you correct an anterior TMJ dislocation?

Answer 12

Move the mandible inferiorly and posteriorly. Be careful to not damage the auriculotemporal n.

Question 13

Describe the course of the maxillary artery and name its three portions

Answer 13

The maxillary artery is one of the terminal branches of the external carotid artery. It passes posterio to the neck of the mandible to enter the infratemporal fossa and gain the pterygopalantine fossa. Its three portions are mandibular, pterygoid, and pterygopalatine.

Question 14

Explain the course of the mandibular portion of maxillary a. and its branches, and what they supply.

Answer 14

Passed deep to the mandibular neck. It’s branches include:
Deep auricular a. - EAM, outer tympanic membrane, and TMJ
Anterior tympanic n. - inner tympanic membrane via the petrotympanic fissure
Middle meningeal a. - cranial dura via the foramen spinosum
Accessory menindeal a. - cranial dura via the foramen ovale
Inferior alveolar a. - supplies the mandible via the mandibular foramen, the mandibular teeth, and the chin via the mental aa. Also provides the mylohyoid artery before entering the mandibular foramen.

Question 15

what is the course of the pterygoid portion of maxillary a? What are its branches?

Answer 15

It’s course is 50/50 deep/superficial to lateral pterygoid
It’s branches include…
Anterior/posterior deep temporal aa., masseteric aa., buccal a., and med/lat pterygoid aa.

Question 16

What are the branches of the pterygopalatine portion of maxillary a.?

Answer 16

Posterior superior alveolar, infraorbital, descending (greater) palatine, artery to pterygoid canal, and sphenopalatine aa.

Question 17

What is the pterygoid plexus of vv.?
Where does it receive blood from (5 locations)?
What vein does it form?
Where does that vein drain to?

Answer 17

The pterygoid plexus of veins is a venous plexus investing the lateral pterygoid m. externally and internally.

This plexus receives blood from…
1&2. Infretemporal fossa and nasa cavity by venae comitantes
3. Face via the deep facial v. and ophtalmic vv.
4. Cavernous sinus through emissary vv.
5. Pharynx via the pharyngeal vv.

Forms the maxillary v which parallels the maxillary a. to exit the infratemporal fossa and join the superficial temporal v. and form the retromandibular v.

Question 18

Describe the course of the Mandibular N. (CN V3) and the fiber types associated with it. Including fibers from other cranial nerves.

Answer 18

CN V1 exits the cranium through foramen ovale to enter the infratemporal fossa.

SVE - innervates the mm. of from the 1st pharyngeal arch: mm. of mastication, anterior digastric, mylohyoid, tensor veli palatini, and tensor tympani mm.

GSA - innervates the lower cheek, chin, mandibular teeth, temporal region, floor of oral cavity, ant. 2/3 of tongue, and dura of the middle cranial fossa.

GVE-P - carries these fibers from CN VII and IX to salivary glands

SVA - carries fibers from CN VII to the anterior 2/3 of tongue

Question 19

Describe the course and innervation of all the GSA branches (Five) of CN V3

Answer 19

Meningeal branch - re-enters the cranial fossa through the foramen spinosum

Buccal branches - exit infratemporal fossa between the two heads of the lateral pterygoid muscle. Innervates the gingivae and internal/external cheek.

Lingual n. - exits the infratemporal fossa between medial and lateral pterygoids. Supplies the anterior 2/3 of tongue, floor of oral cavity, and mandibular gingivae. Joined by chorda tympani to provide SVA to the anterior 2/3 of tongue. Also carries GVE-P of CN VII to salivary glands.

Auriculotemporal N. - exits the infratemporal fossa behind the neck of the mandible after forming from two branches which wrap around the middle meningeal a. Provides GSA to the EAM, external tympanic membrane, auricle, TMJ, and temple. Distributes the GVE-P of CN IX to the parotid gland.

Inferior alveolar n. - provides innervation to the mandibular teeth and the chin via the mental nerve

Question 20

Name the SVE branches (8) of CN V3

Answer 20

Med/lat pterygoid, nn. to tensor tympani/veli palatini, masseteric, ant/post deep temporal, mylohyoid nn.

Question 21

Describe the inferior alveolar nerve and its branches

Answer 21

Supplies innervation to the mandibular teeth and chin via the mental nn.

Provides motor innervation to the mylohyoid and ant. digastric mm. via the mylohyoid n.

Question 22

Where is a mandibular nerve block administered?

Answer 22

through the mandibular notch

Question 23

Where is an inferior alveolar nerve block administered?

Answer 23

Through the mandibular foramen. Commonly used by dentists.

Question 24

Describe the course of the parasympathetic innervation of the parotid gland.

Answer 24

Pre-ganglionic cell bodies lie in the salivatory nucleus of. Their fibers travel with CN IX and follow the tympanic branch to the tympanic canaliculus after exiting the jugular foramen. It enters the middle ear and become the lesser petrosal n. and exit through the lesser petrosal hiatus. Now in the middle cranial fossa the lesser petrosal n. gains the infratemporal fossa through the foramen ovale to synapse on the otic ganglion.
Post-ganglionic cell bodies in the otic ganglion project fibers along the auriculotemporal n. to the parotid gland.

Question 25

Describe the course of parasympathetic innervation to the sublingual and submandibular salivary glands.

Answer 25

Preganglionic cell bodies lie in the salivatory nucleus and travel with chorda tympani. After exiting the petrotympanic fissure the chorda tympani joins lingual n. to synapse at the submanidublar ganglion. Fibers from submandibular ganglion travel with lingual n.