Tongue

Stacks Image 741
The tongue begins development around the 4th week. It begins as a series of primordial in the first through fourth branchial arches. In the first arch, 3 primordial form, a pair of lateral lingual swellings and a midline tuberculum impar.

In the midline of the second, third and fourth arches, a swelling called the hypobranchial eminence or copula appears.
Stacks Image 744
The mucosa of the anterior 2/3 of the tongue, being derived from the first branchial arch is innervated by the lingual branch of V, the nerve of the first arch. The mucosa of the posterior 1/3 of the tongue, being derived from the third branchial arch is innervated by the lingual branch of glossopharyngeal nerve and the root of the tongue from the fourth arch is supplied by the vagus nerve.
Stacks Image 747
The muscles of the tongue, except palatoglossus, are all derived from the occipital myotomes and are therefore supplied by a non branchiomeric arch nerve, the hypoglossal nerve (CN XII). Palatoglossus is derived from the 4th branchial arch and is therefore supplied by the vagus nerve. It is more of a palate muscle than a tongue muscle.