The sphenomandibular ligament is derived from which arch?

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

Answer: (A)

The sphenomandibular ligament comes from the first pharyngeal (mandibular) arch. In development this arch wires the formation of the mandible and related structures, with Meckel’s cartilage as a key element. The sphenomandibular ligament is essentially a fibrous remnant tied to that arch, stretching from the spine of the sphenoid to the lingula of the mandible to help limit how far the jaw can protrude. The other arches generate different ligaments and skeletal pieces—like the second arch giving the stylohyoid ligament and related structures, the third contributing parts of the hyoid, and the fourth to laryngeal elements—so they don’t form this particular jaw-associated ligament.