Philtrum of upper tip is derived from
**Core Concept**
The philtrum of the upper lip is a depression between the nose and the mouth, derived from the embryological development of the face. It is formed by the fusion of the medial nasal prominences.
**Why the Correct Answer is Right**
During embryonic development, the face is formed by the fusion of five facial prominences: two maxillary prominences and one medial nasal prominence from each side of the frontonasal process. The philtrum is formed by the downward growth of the medial nasal prominences, which eventually fuse with the maxillary prominences. This fusion results in the formation of the upper lip, including the philtrum. The philtrum is also influenced by the development of the orbicularis oris muscle, which surrounds the oral cavity.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the philtrum is not derived from the lateral nasal prominences, which contribute to the formation of the nasal alae and the lateral walls of the nasal cavity.
* **Option B:** This option is not relevant to the embryological development of the philtrum.
* **Option C:** This option is incorrect because the mandible is formed by the fusion of the first and second branchial arches, and does not contribute to the formation of the philtrum.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the philtrum is a sensitive area, and its morphology can be affected by various conditions, including cleft lip and palate, and other congenital anomalies. The philtrum is also an important landmark in forensic medicine, as it can provide clues about the identity and ancestry of an individual.
**Correct Answer: C. The medial nasal prominences.**