Australian Dental Council (ADC) Practice Test 2026 - Free ADC Practice Questions and Study Guide

The principal muscle responsible for the opening of the mouth is the anterior belly of the digastric muscle. This muscle plays a key role in depressing the mandible (lower jaw), which in turn facilitates the opening of the mouth.

The anterior belly of the digastric is located beneath the jaw and runs from the mastoid notch of the temporal bone to the digastric fossa of the mandible. When this muscle contracts, it acts to lower the mandible. This action is crucial for various oral functions, including chewing and speaking.

Understanding the anatomy and physiology involved in mouth movements emphasizes the importance of the anterior belly of the digastric in facilitating these essential functions.