Neuroanatomy of the oculomotor system. The nucleus prepositus.

The heterogeneous cytoarchitecture of nucleus prepositus hypoglossi and its multiplicity of afferent and efferent connections to oculomotor structures are described. They are more than adequate to account for a role in eye and head movements: it is suggested that they may provide the neuroanatomical basis for an efference copy signal of eye position, which would also be important in gaze-holding.