National Dental Assisting Examining Board (NDAEB) Practice Exam

What is the labial commissure?

1. Area beneath the tongue

2. Angle at the corner of the mouth where the upper and lower lips join

3. Part of the gums surrounding a tooth

4. Skin around the mouth

The correct answer is: Angle at the corner of the mouth where the upper and lower lips join

The labial commissure refers specifically to the angle at the corner of the mouth where the upper and lower lips meet. It is an important anatomical landmark in the oral cavity and plays a role in facial expressions, speech, and the overall dynamics of mouth movements. Understanding this term is crucial for dental professionals when assessing oral health, as conditions affecting the labial commissure can indicate various issues such as angular cheilitis or other health concerns. In contrast, the area beneath the tongue pertains to the sublingual area, which is related to different anatomical and physiological functions. The part of the gums surrounding a tooth is referred to as the periodontium, which involves structures that support the teeth. The skin around the mouth refers to the perioral region and is another anatomical area totally distinct from the labial commissure. Each of these alternatives highlights different aspects of oral and facial anatomy, but they do not define the specific location and significance of the labial commissure.