Anterior 1/3rd of the tongue develops from which arch
**Core Concept**
The anterior one-third of the tongue develops from the first pharyngeal arch, also known as the mandibular arch. This arch gives rise to the majority of the tongue's musculature and some of its anterior sensory innervation. The first pharyngeal arch is crucial in the embryological development of the face and jaw.
**Why the Correct Answer is Right**
The first pharyngeal arch contributes to the formation of the anterior one-third of the tongue due to the migration of the hypobranchial eminence, a thickening of the ectoderm that eventually gives rise to the anterior two-thirds of the tongue. The hypobranchial eminence is induced by the first pharyngeal arch's mesenchyme, which secretes growth factors that stimulate its growth and differentiation. The anterior one-third of the tongue is primarily composed of the extrinsic tongue muscles, which are innervated by the hypoglossal nerve, a branch of the cranial nerve XII.
**Why Each Wrong Option is Incorrect**
**Option A:** The second pharyngeal arch, also known as the hyoid arch, primarily contributes to the formation of the styloid process, the stylohyoid ligament, and the lesser horn of the hyoid bone. It does not participate in the development of the tongue.
**Option B:** The third pharyngeal arch contributes to the formation of the greater horn of the hyoid bone and the lower part of the hyoid bone. It does not play a role in the development of the tongue.
**Option C:** The fourth pharyngeal arch contributes to the formation of the greater horns of the hyoid bone and the laryngeal cartilages. It does not participate in the development of the tongue.
**Clinical Pearl / High-Yield Fact**
The first pharyngeal arch is a critical structure in the development of the face and jaw. Any disruptions to this arch during embryogenesis can result in congenital anomalies such as cleft lip and palate, and mandibular hypoplasia.
**Correct Answer:** C.