A muscle of mastication involved in opening the mouth exhibits the following characteristics. Identify the in… - INI-CET EXAM -2025

INI-CET EXAM -2025

Applied Anatomy

Easy

Appeared in: INI-CET EXAM -2025

Explanation

The question asks to identify the incorrect statement about the muscle of mastication that opens the mouth, which is the lateral pterygoid.
The statement that this muscle attaches to the medial surface of the mandibular ramus is factually incorrect.
The lateral pterygoid muscle inserts into the pterygoid fovea on the anterior aspect of the neck of the mandible and the articular disc of the temporomandibular joint (TMJ).
It is the medial pterygoid muscle, a jaw elevator, that attaches to the medial surface of the mandibular ramus.

Option B: This is a correct statement. All four muscles of mastication are innervated by the mandibular nerve, a branch of the trigeminal nerve (CN V3).
Option C: This is a correct statement. The superior head of the lateral pterygoid muscle has a direct attachment to the capsule and articular disc of the temporomandibular joint (TMJ).
Option D: This is a correct statement. Bilateral contraction of the lateral pterygoid muscles is the primary force for protruding the mandible (moving the jaw forward).

Visual 1: Diagram - A lateral view of the infratemporal fossa, clearly showing the origins and insertions of the medial and lateral pterygoid muscles. This helps differentiate their attachments on the sphenoid bone and mandible.
Visual 2: Animation - A 3D animation demonstrating the actions of the lateral pterygoid muscle, showing how bilateral contraction causes protrusion and depression (opening) of the mandible, and unilateral contraction causes side-to-side movement.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and function of the muscles of mastication, specifically the lateral pterygoid muscle as background academic context rather than a clinical decision trigger.
Understanding the anatomy of the lateral pterygoid is crucial for diagnosing and managing temporomandibular joint (TMJ) disorders. Spasm or dysfunction of this muscle is a common cause of jaw pain, clicking, and limited mouth opening.
Nurses may assess for lateral pterygoid tenderness by palpating high in the buccal sulcus behind the maxillary tuberosity. Pain upon palpation can indicate muscle inflammation or spasm.
In cases of bruxism (teeth grinding), the lateral pterygoid can become hypertrophied and painful. Patient education on stress reduction, jaw exercises, and the use of night guards is an important nursing intervention.

How to Approach the Question

First, identify the specific muscle being described in the question stem. A 'muscle of mastication involved in opening the mouth' primarily refers to the lateral pterygoid muscle.
Next, carefully read the lead-in: 'Identify the incorrect statement about it.' This means you are looking for the one option that is factually false.
Evaluate each option based on your anatomical knowledge of the lateral pterygoid muscle.
Option A describes an attachment. Recall or look up the insertion of the lateral pterygoid (neck of mandible/TMJ) versus the medial pterygoid (medial ramus).
Option B tests innervation. Recall that all muscles of mastication share the same nerve supply (mandibular nerve).
Options C and D test the muscle's relationship to the TMJ and its primary actions (protrusion). Verify these functions.

Concept Tested & Keywords

Concept Tested: Anatomy and function of the muscles of mastication, specifically the lateral pterygoid muscle.
Stem keywords: muscle of mastication, opening the mouth, mandible
Lead-in keywords: incorrect statement
Negative lead-in flag: The question asks for the INCORRECT statement.

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