As a result of a unilateral lower motor neuron lesion of the hypoglossal nerve

The genioglossus muscle is paralyzed on the side of the lesion in the hypoglossal nerve. When the tongue is protruded, the vector of the fully innervated muscles is unopposed by the muscle on the opposite side, thus producing the obvious detion of the tongue from the midline. Protrusion is still possible due to the normally innervated side. Taste is not related to the muscle innervation of the tongue; it is carried by the trigeminal and glossopharyngeal nerves. Spasticity is a sign of an upper motor neuron lesion. In a lower motor neuron lesion, atrophy of the affected side may be observed by the examiner. Ref - Harrison's internal medicine 20e pg 3028, 3171