Question:easy
In dislocation of the jaw, displacement of the articular disc beyond the temporomandibular (TM) joint results from spasm or excessive contraction of which of the following muscles?
In dislocation of the jaw, displacement of the articular disc beyond the temporomandibular (TM) joint results from spasm or excessive contraction of which of the following muscles?
Show Hint
Find the muscle that attaches to the articular disc itself and pulls the mandible forward.
Updated On: Jul 8, 2026
- Buccinator
- Lateral pterygoid
- Masseter
- Temporalis
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Ask which muscle attaches to the disc.
Of all the muscles of mastication, only the lateral pterygoid sends fibres, from its upper head, directly into the articular disc of the TMJ as well as into the neck of the condyle below.
Step 2: Follow what happens on overcontraction.
Because it attaches to both the disc and the condyle, an overactive or spastic lateral pterygoid drags them both forward, past the bony ridge in front of the joint (the articular eminence). The jaw then gets stuck open, unable to slide back, this is a TMJ dislocation with the disc carried forward too.
Step 3: Check the closing muscles.
Masseter and temporalis pull the jaw shut and upward, the opposite direction needed to cause this forward dislocation, so their overactivity would not push the disc past the eminence. Buccinator is a cheek muscle with no attachment to the joint or disc at all.
Step 4: Conclude.
\[ \boxed{\text{Lateral pterygoid}} \]
Of all the muscles of mastication, only the lateral pterygoid sends fibres, from its upper head, directly into the articular disc of the TMJ as well as into the neck of the condyle below.
Step 2: Follow what happens on overcontraction.
Because it attaches to both the disc and the condyle, an overactive or spastic lateral pterygoid drags them both forward, past the bony ridge in front of the joint (the articular eminence). The jaw then gets stuck open, unable to slide back, this is a TMJ dislocation with the disc carried forward too.
Step 3: Check the closing muscles.
Masseter and temporalis pull the jaw shut and upward, the opposite direction needed to cause this forward dislocation, so their overactivity would not push the disc past the eminence. Buccinator is a cheek muscle with no attachment to the joint or disc at all.
Step 4: Conclude.
\[ \boxed{\text{Lateral pterygoid}} \]
Was this answer helpful?
0
