The intercanthal distance suggestive of traumatic telecanthus is:
**Core Concept**
The intercanthal distance is a critical measurement in assessing facial trauma and telecanthus. Telecanthus refers to an increased distance between the inner corners of the eyes, which can be caused by trauma, developmental disorders, or other conditions affecting the medial canthal tendon. The medial canthal tendon plays a crucial role in maintaining the normal intercanthal distance.
**Why the Correct Answer is Right**
Traumatic telecanthus is often caused by a disruption of the medial canthal tendon, which can lead to an increased intercanthal distance. The medial canthal tendon is formed by the aponeurotic fibers of the orbicularis oculi muscle, which attach to the lacrimal bone and the frontal process of the maxilla. When this tendon is ruptured or stretched, the medial canthus can become widened, resulting in telecanthus. The intercanthal distance is typically measured between the medial canthi, which are the inner corners of the eyes.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the intercanthal distance is not typically measured between the lateral canthi, which are the outer corners of the eyes.
* **Option B:** This option is incorrect because the palpebral fissure width is a measurement of the distance between the eyelid margins, not the intercanthal distance.
* **Option C:** This option is incorrect because the nasolabial angle is a measurement of the angle formed by the nasolabial fold and the nasal ala, not the intercanthal distance.
**Clinical Pearl / High-Yield Fact**
The medial canthal tendon is a critical structure in maintaining the normal intercanthal distance, and its disruption can lead to traumatic telecanthus. It's essential to assess the medial canthal tendon in patients with facial trauma to prevent and diagnose this condition.
**Correct Answer:** C. 21 mm.