Temporomandibular Joint

Question 1

What type of joint is the TMJ

Answer 1

modified synovial hinge joint

Question 2

Flexion of the jaw is…

Answer 2

elevation

Question 3

Extension of the jaw is…

Answer 3

depression

Question 4

Articular surfaces of the TMJ

Answer 4

Mandibular fossa
Articular tubercle
Head of the mandible

Question 5

What movements does the superior articular cavity allow for?

Answer 5

Gliding of the mandible –> protrusion and retrusion

Question 6

What movements does the inferior articular cavity allow for

Answer 6

Hinge , rotational movements

Question 7

How many intrinsic ligaments

Answer 7

1- lateral lig

Question 8

How many extrinsic ligaments

Answer 8

2

• sphenomandibular lig
• stylomandibular lig

Question 9

Lateral ligament

Answer 9

Thickening of jt capsule
From articular tubercle to neck of mandible
Prevents posterior dislocation

Question 10

Sphenomadibular ligament

Answer 10

Spine of the sphenoid bone –> lingua of the mandible

Supports the joint and serves as a prop during hinge movements

Question 11

Stylomandibular ligament

Answer 11

Styloid process to angle of the mandible

Question 12

Temporalis muscle

Answer 12

It originates from the temporal fossa and the deep surface of the temporal fascia. The temporalis inserts on the coronoid process of the mandible and the anterior border of the ramus of the mandible.

It is innervated by deep temporal nerves. The temporalis elevates the mandible and its posterior fibers, which are more horizontal, retrude the mandible.

Question 13

Masseter

Answer 13

strong muscle that originates on the zygomatic arch and the maxillary process of the zygomatic bone.

It inserts on the angle and the lateral surface of the ramus of the mandible. The masseter mainly elevates the mandible, but superficial fibers contribute to protrusion and it’s innervated by the masseteric nerve.

Question 14

medial pterygoid muscle

Answer 14

made of two heads: the deep head and the superficial head.

The deep head originates from the medial surface of the lateral pterygoid plate and the pyramidal process of the palatine bone.

The superficial head originates from the tuberosity of the maxilla. Both heads insert on the medial surface of the ramus and angle of the mandible.

The medial pterygoid muscle is innervated by the medial pterygoid nerve. Bilaterally, it acts very similarly to masseter, producing elevation and protrusion of the mandible. When alternate unilateral contraction occurs it also produces small side-to-side grinding movements of the jaw.

Question 15

Lateral pterygoid muscle

Answer 15

made of two heads. The superior head originates from the infratemporal surface and crest of the greater wing of the sphenoid bone and inserts directly on the joint capsule and the articular disc.

The inferior head originates from the lateral surface of the lateral pterygoid plate and inserts on the pterygoid fovea on the neck of the mandible.

This muscle is innervated by the lateral pterygoid nerve. Bilaterally, the lateral pterygoid muscle is involved in protrusion and depression of the mandible, while unilaterally it helps with lateral or side-to-side chewing movements.