The anatomy and innervation of locust skeletal muscle

The details of the innervation of a skeletal muscle (extensor tibialis of the metathoracic leg) of the locust Locusta migratoria migratorioides R. & F. are described. The muscle is innervated by three nerve fibres supplied from two different nerve trunks. The nerve fibres branch extensively to supply all parts of the muscle. This is composed of bundles of fibres, termed muscle units, each of which receives a discrete branch from the motor nerve and similarly a discrete branch from the tracheal system. The units are pinnately arranged along the whole length of the femur. A study of the finest branches of the nerves reveals the presence of several tiny twiglets of nerve, each containing usually two fibres, ending on each muscle fibre. The endings take the form of fine, nucleated claws on the surface of the fibre, which can be detached by pulling and may be individual end-plates. The innervation of other locust muscles is briefly compared.