ANATOMY AND PHYSIOLOGY OF TMJ AND PALATE

Question 1

On examination patient has limited mouth opening of 25mm.

What is the mouth opening for normal people? What are the muscles of mastication? (3)

Answer 1

 Minimum mouth opening: Male > 40 mm / Female > 35 mm

 Lateral excursion 8 mm

 Temporalis, masseter, medial pterygoid m, lateral pterygoid muscle

Question 2

Given: panoramic radiograph. Generalized horizontal bone loss Multiple missing teeth: 18, 16, 24, 25, 26, 27, 38, 31, 41, 42, 48 Periapical radiolucency, Furcation involvement , Tilting

a. What is fovea palatini?

Answer 2

 Orifice of minor palatine glands
 An anatomical landmark for the vibrating line, which is 2 mm posterior to the vibrating line

Question 3

Given: panoramic radiograph. Generalized horizontal bone loss Multiple missing teeth: 18, 16, 24, 25, 26, 27, 38, 31, 41, 42, 48 Periapical radiolucency, Furcation involvement , Tilting

b. Draw Posselt’s Envelope. Mark the major points.

Answer 3

Question 4

32 y.o. female, busy bank clerk, complained of left TMJ pain, patient mentioned about occasional clicking. pain on palpation of MOM, trismus, jaw deviation to the left upon opening.
Radiograph shows articulating disc of left TMJ is displaced anteriorly when the mouth is closed, but is in normal position when the mouth is opened

a. Name 4 components of TMJ (4)

Answer 4

 Condyle, articular disc, temporal bone, fibrous capsule and associated ligaments

Question 5

32 y.o. female, busy bank clerk, complained of left TMJ pain, patient mentioned about occasional clicking. pain on palpation of MOM, trismus, jaw deviation to the left upon opening.
Radiograph shows articulating disc of left TMJ is displaced anteriorly when the mouth is closed, but is in normal position when the mouth is opened

b. 2 movements of the TMJ (2)

Answer 5

 Rotation and translation

Question 6

32 y.o. female, busy bank clerk, complained of left TMJ pain, patient mentioned about occasional clicking. pain on palpation of MOM, trismus, jaw deviation to the left upon opening.
Radiograph shows articulating disc of left TMJ is displaced anteriorly when the mouth is closed, but is in normal position when the mouth is opened

c. What is the normal range of maximum mouth opening? (1)

Answer 6

 Assisted range of motion: male > 40 mm, female > 35 mm (including overlap)

 Lateral 8 mm, protrusion 6 - 8 mm
 ***Book’s word is “Minimal / lower limit” opening