What condition is described by an inability to open the mouth normally?

The condition characterized by an inability to open the mouth normally is known as trismus. This term specifically refers to a restriction of the jaw, often resulting from spasms of the muscles used for jaw movement. Trismus can occur due to various reasons, including dental issues, infections in the jaw or throat, or conditions that affect the muscles and joints of the jaw.

In contrast, temporomandibular dysfunction primarily encompasses a range of issues affecting the temporomandibular joint (TMJ) and the surrounding muscles, which can lead to pain and jaw movement problems. Although it can cause limited jaw opening, it is not exclusively defined by that symptom alone.

Oral lichen planus is an inflammatory condition that affects the mucous membranes inside the mouth and does not typically result in mechanical difficulty opening the mouth.

Jaw dislocation refers to a condition in which the jaw is displaced from its normal position, often causing acute pain and an inability to close or open the mouth properly, but it is usually associated with an acute episode rather than a chronic inability to open the mouth which trismus describes.