Surface Palpation - Head and Neck - Muscles
Depressor Labii Inferioris
Sitting or standing
 
Anterior to the patient
 
Please sit (or stand). I would like to check the function of a muscle just below your lower lip. Please look at this picture of a person pulling the lower lip downward as if you were crying. (Or . . . Please look at me while I try to mimic crying with my lower lip pulled down.) May I touch the skin below your bottom lip?
(If the answer is yes) I will gently place my fingers below your lip while you try this expression. Please try this expression, then relax and try again.
(If the answer is no) Please try this expression, then relax and try again while I observe.
The patient/client is sitting (or standing) and either facing a mirror or facing the person who will mimic an expression of crying. The lower lip is pulled downward and the lower teeth may or may not be exposed, an expression that looks like crying. After showing a picture or demonstrating the expression, ask the patient/client to perform the expression. With the muscle relaxed initially and with permission, gently place one or two fingers below the center of the patient/client's lower lip and ask the person to mimic crying. Ask the person to relax and repeat if necessary. If permission is not granted, then observe as the person mimics crying, relaxes and then mimics crying again.

In the video, the depressor labii inferioris and the depressor anguli oris both are palpated during a facial expression resembling crying. The depressor labii inferioris is palpated inferior to the center of the lower lip and the depressor anguli oris is palpated inferior to the angle or corner of the mouth. These two muscles are continuous with the platysma and could be active with contraction of the platysma, and especially during the facial expression which resembles crying. Activation of the mentalis during these videos can be observed as wrinkles of the skin over the chin; however this muscle is not palpated. In all cases, the depressor labii inferioris muscle pulls the lower lip down.

These palpations show demonstration of finger placement after muscle activation to allow better viewing, as well as before muscle activation. The correct technique of palpation of muscle includes the sequence of muscle activation, relaxation of the muscle, placement of the fingers on the muscle before the muscle is activated, activation of the muscle, and relaxation of the muscle.