Citelli’s angle is
**Core Concept**
Citelli's angle is a radiological landmark used in the assessment of temporomandibular joint (TMJ) disorders. It is an important anatomical feature for the diagnosis of internal derangements of the TMJ. The angle is formed by the intersection of the petrous ridge and the posterior wall of the external auditory meatus.
**Why the Correct Answer is Right**
Citelli's angle is used to determine the position of the articular disc in relation to the mandibular condyle in the TMJ. A normal Citelli's angle is between 110° and 120°. When the angle is greater than 120°, it indicates a posteriorly displaced articular disc, which is a common finding in TMJ internal derangements. This displacement can lead to reduced joint space and altered joint mechanics, resulting in pain and limited jaw movement.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a correct description of Citelli's angle. Citelli's angle is not related to the angle between the articular disc and the mandibular condyle.
**Option B:** This option is incorrect as it does not accurately describe the anatomical relationship between the petrous ridge and the posterior wall of the external auditory meatus.
**Option C:** This option is not relevant to Citelli's angle, which is a radiological landmark used in TMJ assessment.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that an abnormal Citelli's angle can indicate internal derangements of the TMJ, which may require further evaluation and treatment to prevent long-term joint damage.
**Correct Answer:** C.