In carcinoma base of tongue pain is referred to the ear through:

(c) Glossopharyngeal nerve(Ref. Cummings, 6th ed., 1364, Scott Brown, Vol 3; 643)The base of tongue is mainly supplied by the glossopharyngeal nerve which also supplies the ear.Note:Anterior 2/3rds of tongue is supplied by lingual nerve (a branch of mandibular). Auriculotemporal nerve also a branch of mandibular nerve supplies the ear so in carcinoma anterior 2/3rds of tongue pain is referred to ear through mandibular nerve.Posterior 1/3rd, i.e. the base of the tongue is mainly supplied by glossopharyngeal nerve and the posterior most part of this posterior 1/3rd tongue is supplied by vagus, both of which also supply the ear, so in carcinoma of this part of tongue, pain will be referred to ear through both glossopharyngeal and vagus.But since glossopharyngeal supplies most of the base of the tongue so in pathologies of base of tongue the pain is referred to the ear mainly through the glossopharyngeal nerve.