The nerve supply of the tongue is quite complex. It is understandably so because of the multiplicity of its functions. The tongue is a muscle mass occupying most of the oral cavity and it plays a very important role in taste. It is also involved in chewing, swallowing, speech and oral cleaning.
To perform these roles, the tongue is equipped with four intrinsic and four extrinsic muscles. The extrinsic muscles originate outside the tongue and insert in the body of the organ while intrinsic muscles are exclusively located within the substance of the tongue.
The intrinsic muscles are the superior longitudinal, the inferior longitudinal, the transverse and the vertical. The extrinsic muscles are the genioglossus, the hyoglossus, the styloglossus and the palatoglossus. With the exception of the palatoglossus muscle, the motor function of the seven other intrinsic and extrinsic muscles of the tongue is controlled by the hypoglossal nerve. The palatoglossus muscle is controlled by the pharyngeal plexus of the vagus nerve.
The sense of taste in the anterior two thirds of the tongue (excluding the vallate papillae) is controlled by the chordae tympani branch of the facial nerve while taste in the posterior one third (excluding the vallate papillae) is controlled by the lingual branch of the glossopharyngeal nerve.
Touch and temperature sense in the anterior two thirds is controlled by the lingual branch of the trigeminal nerve while in the posterior one third, touch and temperature sense is controlled by the lingual branch of the glossopharyngeal nerve.