The 5th cranial nerve is the trigeminal nerve and supplies the majority of the oral cavity. A branch of the mandibular division runs from the inner surface of the ramus of the mandible and then over the external oblique ridge to supply the surrounding gingivae. Which of the following is the name of this branch?

• A. Lingual nerve
• B. Inferior alveolar nerve
• C. Long buccal nerve
• D. Mental nerve

Answer: (C)

The nerve being described is the long buccal nerve. This branch comes from the mandibular division of the trigeminal nerve and travels along the cheek, running between the buccinator and the masseter. It then crosses the external oblique ridge on the mandible to reach and supply the buccal (cheek) gingiva around the molar and premolar teeth. That path and target match exactly what’s described: a branch from V3 that courses along the inner surface area of the ramus and over the external oblique ridge to innervate the surrounding gingivae.

Other nerves listed don’t fit this pattern. The lingual nerve mainly provides sensation to the anterior two-thirds of the tongue and the floor of the mouth, with some innervation to lingual gingiva rather than buccal gingiva. The inferior alveolar nerve travels within the mandibular canal to supply the lower teeth and associated structures and gives off the mental nerve to the chin and lower lip, not the buccal gingiva. The mental nerve itself supplies the chin and lower lip mucosa, not the gingiva of the cheek side.