Anatomy_الفصل الثاني

Nerve supply of the tongue: Innervation of the tongue consists of motor fibers, special sensory fibers for taste, and general sensory fibers for sensation. 1. Motor supply for all intrinsic and extrinsic muscles of the tongue is supplied by the hypoglossal nerve (CN XII), with the exception of the palatoglossus. The palatoglossus is innervated by the vagus nerve. 2. Innervation of taste and sensation is different for the anterior and posterior part of the tongue because they are derived from different embryological structures. a. Anterior two thirds of tongue (anterior to the vallate papillae): -Taste: chorda tympani branch of the facial nerve (CN VII) -Sensation: lingual branch of the mandibular division (V3) of the trigeminal nerve (CN V) b. Posterior one third of tongue: -Taste and sensation: glossopharyngeal nerve (CN IX) c. Base of tongue -Taste and sensation: internal laryngeal nerve (branch of CN X, vagus nerve)