The homunculus is a model that describes the neural relations between cortical areas on the one hand, and skeletal muscels or sensory areas on the other hand, where proximate body regions are pictured on proximate cortex areas. Thus it represents the somatotopic arrangement of motor efferences or sensory afferences on respective cortex areas. Accordingly one can differentiate between a sensory and a motor homunculus.
(Scheme modified from the Homunkulus of canadian neurosurgeon Wilder Penfield)