Week 9.1 - TMJ and infratempora fossa Flashcards
What is the TMJ?
-Articulation between the cranium and the mandible which facilitates jaw movement
Name the main bony features of the TMJ
- Mandible head
- Articular tubercle
- Mandibular fossa
What type of joint is the TMJ?
-Synovial
Describe the fibrocartilage of the TMJ
-Covers both articular surfaces and also there is a fibrocartilage disk which separates the joint into two cavities (superior and inferior)
Why is the articular disk of the TMJ important?
- 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
Describe the capsule of the TMJ
-Loose and thin to allow movement but this sacrifices stability
What is the main ligament of the TMJ which stengthens? Where is it?
-Temperomandibular ligament
-From zygoma to ramus of mandible
(2 medial ligaments also stengthen)
Name the accessory ligaments of the TMJ
- Sphenomandibular
- Stylomandibular
What is the function of the accessory ligaments of the TMJ?
-Prevent inferior dislocation
What separates the parotid from the submandibular gland? Why is this relevant to TMJ?
- Deep parotid fascia
- Stylomandibular ligament forms part of this
When is the jaw least stable?
-When it is open
Why does occlusion of the teeth aid stabilisation?
-Most force is transferred through the teeth
What limits posterior displacement of the jaw?
-Posterior glenoid tubercle
What limits anterior displacement of the mandible?
-Articular tubercle
What two types of movements produce all movements of the jaw?
-Translation and rotation
Which cavity of the TMJ produces which movement?
- Superior produces translation
- Inferior produces rotation
Describe the movements which open the mouth
- Translation as the condyles are pulled forward by the lateral pterygoids
- Rotation as the chin is pulled down by digastric
Describe the movements which close the mouth
- Retraction of the mandible by posterior fibres of temporalis
- elevation of the mandible by temporalis, masseter and medial pterygoid
What is bruxism?
-grinding of the teeth during sleep
What is the infratemporal fossa?
-Irregular shaped cavity which lies below the middle cranial fossa, behind the maxilla and zygoma
State the boundaries of the infratemporal fossa
- lateral -> ramus of mandible
- medial -> lateral pterygoid plate of sphenoid
- Anterior -> posterior surface of maxilla
- Posterior -> Carotid sheath
Name the muscular contents of the infratemporal fossa
- Temporalis
- Medial pterygoid
- Lateral pterygoid
Which nerves run through the infratemporal fossa?
- Otic ganglion
- Chorda tympani
- Mandibular nerve gives branches auriculotemporal, inferior alveolar, buccal and lingual
What are the arterial contents of the infratemporal fossa?
- Maxillary artery (ECA) travels through the fossa
- Middle meningeal artery branches off here (travels into the cranium by foramen spinosum)
Describe the venous contents of the infratemporal fossa
- Pterygoid plexus
- Maxillary vein
- Middle meningeal vein
State the openings into the infratemporal fossa
- Foramen ovale (CNV3)
- Foramen spinosum (MMA)
- Alveolar canal
Why are nerve blocks of relevance to the infratemporal fossa?
- Inferior alveolar nerve block used in dentistry
- Mandibular nerve block used to block inferior alveolar, buccal, lingual and auriculotemporal
