Week 9.1 - TMJ and infratempora fossa

Question 1

What is the TMJ?

Answer 1

-Articulation between the cranium and the mandible which facilitates jaw movement

Question 2

Name the main bony features of the TMJ

Answer 2

• Mandible head
• Articular tubercle
• Mandibular fossa

Question 3

What type of joint is the TMJ?

Answer 3

-Synovial

Question 4

Describe the fibrocartilage of the TMJ

Answer 4

-Covers both articular surfaces and also there is a fibrocartilage disk which separates the joint into two cavities (superior and inferior)

Question 5

Why is the articular disk of the TMJ important?

Answer 5

• Bones are poorly aligned so allows them to fit

- Adds stabilisation of the joint as it is thinner in the centre and thicker at the edges

Question 6

Describe the capsule of the TMJ

Answer 6

-Loose and thin to allow movement but this sacrifices stability

Question 7

What is the main ligament of the TMJ which stengthens? Where is it?

Answer 7

-Temperomandibular ligament
-From zygoma to ramus of mandible
(2 medial ligaments also stengthen)

Question 8

Name the accessory ligaments of the TMJ

Answer 8

• Sphenomandibular

- Stylomandibular

Question 9

What is the function of the accessory ligaments of the TMJ?

Answer 9

-Prevent inferior dislocation

Question 10

What separates the parotid from the submandibular gland? Why is this relevant to TMJ?

Answer 10

• Deep parotid fascia

- Stylomandibular ligament forms part of this

Question 11

When is the jaw least stable?

Answer 11

-When it is open

Question 12

Why does occlusion of the teeth aid stabilisation?

Answer 12

-Most force is transferred through the teeth

Question 13

What limits posterior displacement of the jaw?

Answer 13

-Posterior glenoid tubercle

Question 14

What limits anterior displacement of the mandible?

Answer 14

-Articular tubercle

Question 15

What two types of movements produce all movements of the jaw?

Answer 15

-Translation and rotation

Question 16

Which cavity of the TMJ produces which movement?

Answer 16

• Superior produces translation

- Inferior produces rotation

Question 17

Describe the movements which open the mouth

Answer 17

• Translation as the condyles are pulled forward by the lateral pterygoids
• Rotation as the chin is pulled down by digastric

Question 18

Describe the movements which close the mouth

Answer 18

• Retraction of the mandible by posterior fibres of temporalis
• elevation of the mandible by temporalis, masseter and medial pterygoid

Question 19

What is bruxism?

Answer 19

-grinding of the teeth during sleep

Question 20

What is the infratemporal fossa?

Answer 20

-Irregular shaped cavity which lies below the middle cranial fossa, behind the maxilla and zygoma

Question 21

State the boundaries of the infratemporal fossa

Answer 21

• lateral -> ramus of mandible
• medial -> lateral pterygoid plate of sphenoid
• Anterior -> posterior surface of maxilla
• Posterior -> Carotid sheath

Question 22

Name the muscular contents of the infratemporal fossa

Answer 22

• Temporalis
• Medial pterygoid
• Lateral pterygoid

Question 23

Which nerves run through the infratemporal fossa?

Answer 23

• Otic ganglion
• Chorda tympani
• Mandibular nerve gives branches auriculotemporal, inferior alveolar, buccal and lingual

Question 24

What are the arterial contents of the infratemporal fossa?

Answer 24

• Maxillary artery (ECA) travels through the fossa

- Middle meningeal artery branches off here (travels into the cranium by foramen spinosum)

Question 25

Describe the venous contents of the infratemporal fossa

Answer 25

• Pterygoid plexus
• Maxillary vein
• Middle meningeal vein

Question 26

State the openings into the infratemporal fossa

Answer 26

• Foramen ovale (CNV3)
• Foramen spinosum (MMA)
• Alveolar canal

Question 27

Why are nerve blocks of relevance to the infratemporal fossa?

Answer 27

• Inferior alveolar nerve block used in dentistry

- Mandibular nerve block used to block inferior alveolar, buccal, lingual and auriculotemporal