Distributed ‘End-Plate Potentials’ of Crustacean Muscle Fibres

1. The importance of the spatial distribution of motor nerve endings in crustacean muscle is discussed. 2. The spread of the ‘end-plate potential’ (e.p.p.) has been mapped out in individual crustacean muscle fibres using intracellular recording. 3. The e.p.p. is distributed over the whole length of the fibre with relatively small variations of its local amplitude. In any one of fourteen individual fibres, the size of the e.p.p. varied by less than a factor of two along 5-6 mm. of fibre length, the average range of variation being 1.4. A sharp focal e.p.p. was only seen in a partially ‘denervated’ muscle fibre. 5. These experiments support the view that motor nerve endings are widely distributed along the length of crustacean muscle fibres.