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The gill arches have both nerves and arteries as well as entodermal and ectodermal coverings that close the gill slits. Motor nerves are related to muscles of the arches while the sensory nerves relate to the entodermal and ectodermal derived tissues of the arches and pouches. The first arch (I) forms the upper and lower jaw and are innervated by the motor 5th nerve for the muscles for mastication. These muscles act between the two jaws formed by arch 1. The pouch (oral and nasal cavity) and the external surface of the jaws are innervated by the sensory fifth nerve.
The gill arches have both nerves and arteries as well as entodermal and ectodermal coverings that close the gill slits. Motor nerves are related to muscles of the arches while the sensory nerves relate to the entodermal and ectodermal derived tissues of the arches and pouches. The first arch (I) forms the upper and lower jaw and are innervated by the motor 5th nerve for the muscles for mastication. These muscles act between the two jaws formed by arch 1. The pouch (oral and nasal cavity) and the external surface of the jaws are innervated by the sensory fifth nerve.