A somatotopic and functional representation of the respiratory muscles in the trigeminal and facial motor nuclei of the carp (Cyprinus carpio L.).

The place of the cells innervating six most important respiratory muscles in the carp (Cyprinus carpio L.) were determined by means of the horseradish peroxidase technique. It was found that these muscles are represented in the rostral and caudal subdivisions of the trigeminal and facial motor nuclei. All connections were ipsilateral. The distribution of the various cell populations over the different subnuclei has been related to the function of the respective muscles in the respiratory cycle. On these grounds it could be concluded that muscles active in the contraction phase of respiration are represented in the rostral subnuclei, the expansion muscles in the caudal subnuclei. This arrangement appears to be a compromise between a somatotopic and functional and functional organization.