Question

A newborn had hypoplasia of the mandibles and zygomatic bones, malformed external ears, and slanted palpebral fissures. Abnormality in the development of which of the following pharyngeal arches will most likely lead to the given condition?

• A. Pharyngeal arch 1
• B. Pharyngeal arch 2
• C. Pharyngeal arch 3
• D. Pharyngeal arch 4

Hint:

Pierre Robin sequence is often associated with abnormal development of pharyngeal arch 1. It is important to diagnose early to manage airway and feeding issues.

Answer 1

The Correct Option is A

Pharyngeal arch 1: Pharyngeal arch 1 contributes to the development of the mandible, zygomatic bone, maxilla, and external ear. Malformations in this arch can lead to Pierre Robin sequence, characterized by micrognathia (small mandible), cleft palate, and other facial anomalies, such as malformed external ears and slanted palpebral fissures.
Pharyngeal arch 2: This arch primarily gives rise to structures in the face, such as the facial nerve, stapes of the ear, and part of the hyoid bone, but it does not directly affect the mandible or zygomatic bones.
Pharyngeal arch 3: This arch contributes to the stylopharyngeus muscle and part of the hyoid bone, but it does not significantly influence the development of the mandible or zygomatic bones.
Pharyngeal arch 4: This arch contributes to the laryngeal cartilages and muscles, not the mandible or zygomatic bones. Thus, the correct answer is Pharyngeal arch 1 (1), as abnormalities in this arch are most likely to cause the given craniofacial defects.