Head and Neck 2 - TMJ Flashcards
Which joint is the only joint in the body that partially dislocates every time you use it?
Temporomandibular joint (TMJ)
What can cause a higher incidence of TMJ dysfunction?
Anxiety and sleep disorders
Describe the mandible
Formed by a union, in the midline, of 2 halves each having a horizontal body and a vertical ramus
Where is the angle of the mandible?
Where the body and ramus meet
Which 2 processes are at the superior end of the ramus?
Coronoid process
Condylar process/head of condoyle
Which is the only muscle that opens the mouth?
Lateral pterygoid muscle
When does the mandible fuse?
In-utero
Where is the mental foreman located and which nerve passes through here?
In the body of the mandible
Mental nerve
Where is the mandibular fossa located?
On the temporal bone
Where is the articular tubercle located?
The squamous part of the temporal bone
What type of joint is the TMJ?
Synovial joint of the condyloid type - modified hinge joint
What type of cartilage covers the articular surface of the TMJ?
Fibro-cartilage - usually hyaline cartilage
Which structure within the capsule divides the the cavity into superior and inferior compartments?
Fibrocartilaginous disc
Describe the articular disc
- A fibrocartilaginous disc
- Margins are attached to the capsule
- Divides the compartment into superior and inferior compartments
- Concave undersurface and concavoconvex upper surface - jockey’s cap
Which compartment allows 1) gliding of the TMJ and 2) hinge movement of the TMJ?
1) Upper compartment
2) Lower compartment
What are the functions of the TMJ?
Depression: opening the mouth
Elevation of the mandible: closing the mouth
Protrusion: push chin forward
Retraction: move mandible back
What is the most common injury of the jaw?
Lockjaw: forward dislocation (jaw sticks out; protrusion)
What is the blood supply for the TMJ?
External carotid artery: superficial temporal and maxillary branches
What is the nerve supply for the TMJ?
Auriculotemporal and masseteric nerves which are both derived from Vc (mandibular division of the trigeminal nerve)
What are the 4 muscles of mastication?
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
Which muscle of mastication is for depression of the mouth?
Lateral pteryoid - the only muscle that opens your mouth
What is the function of the medial pterygoid muscle?
Elevation and protrusion of the mandible
Where does the medial pterygoid muscle insert?
Arises from the medial surface of the lateral pterygoid plate and inserts onto the medial surface of the angle of mandible and ramus
Which structures does the lateral pterygoid muscle insert into?
Arises from infra-temporal surface of the greater wing of sphenoid and lateral surface of the lateral pterygoid plate and inserts into neck of mandible at the fovea and to the capsule an the intra-capsular disc
