Masseteric, Temporal And Infratemporal Regions

Front 1

Where is the masseteric region?

Back 1

On the side of the head, inferior to the zygomatic arch and lateral to the ramus of the mandible.

Front 2

What is the masseter?

Back 2

A muscle of mastication. One of the strongest muscles in the body.
O: zygomatic arch
I: outer surface of the ramus of mandible
Inv: Masseteric n. (motor branch of the mandibular division of the trigeminal nerve V3)
A: Elevation of the mandible, can also produce lateral movement (grinding)

Front 3

Where is the temporal region?

Back 3

On the side of the head above the external auditory meatus and the zygomatic arch. Includes the temporal fossa that contains the temporalis muscle.

Front 4

What is the temporalis?

Back 4

A muscle of mastication.
O: temporal fossa (?)
I: coronoid process of mandible
Inv: deep temporal n. (branch of the mandibular division of the trigeminal nerve V3)
A: contraction of anterior fibers-elevates mandible
contraction of posterior fibers-retracts mandible

Front 5

Describe the fibers of the temporalis muscle.

Back 5

Oriented both vertically (anterior fibers) and horizontally (posterior fibers).

Front 6

Where is the infratemporal region?

Back 6

Inferior to the temporal fossa and deep to the ramus of the mandible.

Front 7

What are the boundaries of the infratemporal region?

Back 7

Lateral wall - ramus of mandible
Anterior wall - body of the maxilla (eggshell thickness)
Medial wall - lateral plate of the pterygoid process
Roof - formed by the under surface of the greater wing of the sphenoid bone

Front 8

What is the pterygopalatine fossa?

Back 8

A triangular space medial to the site where the lateral plate of the pterygoid process hits the maxilla.

Front 9

What openings are in the pterygopalatine fossa?

Back 9

The opening from the infratemporal fossa to the pterygopalatine is called the pterygomaxillary fissure. This joins with the inferior orbital fissure at a right angle.

Front 10

What are the contents of the pterygopalatine fossa?

Back 10

-pterygopalatine ganglion
-3rd part of the maxillary artery

Front 11

What perforates the infratemporal fossa?

Back 11

-foramen ovale
-foramen spinosum

Front 12

What are the contents of the infratemporal fossa?

Back 12

-pterygoid muscles
-maxillary artery
-pterygoid plexus (a venous plexus)
-several nerves

Front 13

What is the medial pterygoid muscle?

Back 13

The most medial structure in the infratemporal region.
O: medial surface of the lateral pterygoid plate
I: medial surface of the ramus
Inv: nerve to the medial pterygoid muscle
A: elevation of mandible, lateral (grinding) movements of mandible

Front 14

What is the lateral pterygoid muscle?

Back 14

O: roof and medial wall of the infratemporal fossa
I: 1. anterior part of the neck of the mandible and 2. on the articular disc of the temporomandibular joint
Inv: nerve to lateral pterygoid
A: depression and protrusion of the mandible

Front 15

What nerve enters the infratemporal fossa?

Back 15

The mandibular nerve (CN V3) of the trigeminal nerve enters via the foramen ovale. Forms a trunk about 2-3 mm.

Front 16

What are the branches of the trunk of the mandibular n.?

Back 16

-meningeal n.
-nerve to the medial pterygoid m.

Front 17

What is the anterior division of the mandibular nerve?

Back 17

Mainly motor. Branches include:
-masseteric n.
-deep temporal n.
-buccal (sensory) n.
-nerve to the lateral pterygoid muscle

Front 18

What is posterior division of the mandibular nerve?

Back 18

Mainly sensory. Branches include:
-auriculotemporal n.
-lingual n.
-inferior alveolar n.

Front 19

What artery supplies the infratemporal fossa?

Back 19

The maxillary artery, is divided into three parts.

Front 20

What does the second branch of the maxillary artery supply?

Back 20

All the muscles of mastication and the buccinator muscle.

Front 21

What branches of the maxillary artery do we need to know?

Back 21

-middle meningeal a. (to dura of brain)
-inferior alveolar a. (to lower teeth)
-sphenopalatine a. (to nasal cavity)

Front 22

What is the pterygoid plexus?

Back 22

Forms around the pterygoid muscles, ends as the maxillary vein, which eventually joins the superficial temporal vein to form the retromandibular vein.

Front 23

What are the important connections does the pterygoid plexus have?

Back 23

Has important connections with the:
1. cavernous sinus via the foramen ovale
2. facial vein via the deep facial vein
3. pharyngeal plexus of veins

Front 24

What is the otic ganglion?

Back 24

A parasympathetic ganglion, important relay station for the preganglionic parasympathetic fibers of the glossopharyngeal n. (CN IX) destined for the parotid gland.

Front 25

What brings preganglionic fibers to the otic ganglion?

Back 25

The lesser petrosal n. descends through the foramen ovale bringing preganglionic fibers to the otic ganglion; the postganglionic fibers travel with the auriculotemporal n to the parotid gland.

Front 26

What is the temporomandibular joint?

Back 26

TMJ. Has 2 joint cavities that are filled with synovial fluid, joint between mandible and temporal bone.

Front 27

What are the bony parts of the TMJ?

Back 27

-head of the mandible
-articular surface of the mandibular fossa
-articular tubercle of the temporal bone

Front 28

What is the articular disc?

Back 28

It caps the head of the mandible and projects forward under the articular tubercle, dividing the joint cavity into upper and lower compartments.

Front 29

What type of movement does the articular disc allow?

Back 29

Simple hinge movements. One on each side, upper and lower cavities.

Front 30

What type of movement does the lower joint cavity of the TMJ allow?

Back 30

Depression and elevation of the mandible.

Front 31

What type of movement does the upper joint cavity of the TMJ allow?

Back 31

Protrusion and retraction of the mandible.

Front 32

What ligaments are external to the TMJ joint capsule?

Back 32

-lateral temporomandibular ligament (the thickened joint capsule)
-stylomandibular ligament
-sphenomandibular ligament

Front 33

What muscles of mastication elevate the mandible?

Back 33

-vertical fibers of temporalis
-masseter
-medial pterygoid

Front 34

What muscles of mastication depress the mandible?

Back 34

Accomplished by gravity and:
-anterior belly of digastric
-mylohyoid
-lateral pterygoid

Front 35

What muscles of mastication move the mandible laterally?

Back 35

Ipsilateral (same side):
-temporalis
-masseter
Contralateral:
-medial pterygoid

Front 36

What muscles of mastication protrude the mandible?

Back 36

Just the lateral pterygoid.

Front 37

What muscles of mastication retract the mandible?

Back 37

Just the horizontal fibers of the temporalis.