Which cranial nerve is most likely to have a lesion for a patient who is unable to taste a piece of sugar placed on the anterior part of the tongue?

Facial nerve- taste fibers to the anterior 2/3 of the tongue come from the chorda tympani-a branch of the facial nerve. so, if the patient has lost taste sensation to the anterior 2/3 of the tongue, the patient might have a lesion of the facial nerve. the glossopharyngeal nerve (cn ix) carries taste and general sensory fibers to the posterior 1/3 of the tongue. the hypoglossal nerve (cn xii) gives motor innervation to all the muscles of the tongue (ie, all the muscles that end in glossus except for palatoglossus, which is a palate muscle innervated by the vagus). the trigeminal nerve supplies general sensory fibers to the anterior 2/3 of the tongue via the lingual nerve, a branch of v3. remember, the chorda tympani fibers jump on the lingual nerve to reach the tongue, but the chorda tympani fibers originate from the facial nerve! Finally, the vagus nerve supplies general and taste sensation to a very small part of the posterior tongue, right next to the epiglottis.