College of Massage Therapists of British Columbia (CMTBC) Practice Exam

Which two muscles are responsible for rotating the condyles of the temporomandibular joint (TMJ)?

1. Masseter and temporalis

2. Medial pterygoid and lateral pterygoid

3. Temporalis and lateral pterygoid

4. Digastric and mylohyoid

The correct answer is: Temporalis and lateral pterygoid

The correct answer identifies the temporalis and lateral pterygoid muscles as responsible for the rotation of the condyles of the temporomandibular joint (TMJ). The temporalis muscle plays a crucial role in the elevation and retraction of the mandible, but it also aids in the rotational aspect of the TMJ movement, particularly in the posterior fibers. The lateral pterygoid muscle is essential for the lateral movements and the forward and backward movements of the mandible, directly influencing the rotation of the condyles during these activities. This muscle contracts to allow the head of the mandible to rotate around the condylar axis, facilitating complex movements such as chewing and speaking. Thus, the combination of these two muscles allows for effective rotational movement of the TMJ, contributing to the overall function of the jaw. In contrast, while the masseter and medial pterygoid muscles are involved in elevating the mandible, they do not significantly contribute to rotational movement. The digastric and mylohyoid muscles primarily facilitate depression of the mandible rather than rotation.