Which arch forms the stylohyoid muscle and the posterior belly of the digastric muscle?

Which arch forms the stylohyoid muscle and the posterior belly of the digastric muscle?

• A. First pharyngeal arch
• B. Second pharyngeal arch
• C. Third pharyngeal arch
• D. Fourth pharyngeal arch

Answer: (B)

The second pharyngeal arch, also called the hyoid arch, is the one that forms the stylohyoid muscle and the posterior belly of the digastric. In development, each pharyngeal arch has its own set of muscles and cartilage; the second arch specifically gives rise to several muscles involved in swallowing and facial aspects, including the stylohyoid and the posterior belly of the digastric. These muscles work together to elevate and position the hyoid bone during swallowing and to assist in opening the jaw. The arch also contributes cartilage (Reichert’s cartilage) that helps form parts of the styloid process and the greater involvement of hyoid elements, and its derivatives are innervated by the facial nerve (CN VII). This combination of muscle origin and cartilaginous derivatives points to the second arch as the source.

The second pharyngeal arch, also called the hyoid arch, is the one that forms the stylohyoid muscle and the posterior belly of the digastric. In development, each pharyngeal arch has its own set of muscles and cartilage; the second arch specifically gives rise to several muscles involved in swallowing and facial aspects, including the stylohyoid and the posterior belly of the digastric. These muscles work together to elevate and position the hyoid bone during swallowing and to assist in opening the jaw. The arch also contributes cartilage (Reichert’s cartilage) that helps form parts of the styloid process and the greater involvement of hyoid elements, and its derivatives are innervated by the facial nerve (CN VII). This combination of muscle origin and cartilaginous derivatives points to the second arch as the source.