Development of Peripheral Neural Connections with Muscles and Sensory Receptors
The nerve supply of skeletal muscles is very constant; except for rare anomalies, each muscle is innervated by a specific group of motoneurons. This has been demonstrated by cutting various peripheral nerves and then observing that chromatolysis is confined to a localized group of motoneurons whose axons have been cut (Romanes, 1946; Szentágothai, 1948, 1949). More recently, accurate mapping of relations between muscles and motoneurons has been done by tracing the retrograde flow of horseradish peroxidase injected into the vicinity of motor nerve terminals in the muscles (Kristensson and Olsson, 1971, 1973; Kristensson, 1975, review). Not only do the axons of motoneurons supply specific muscles, but also their dendrites form specific connections within the spinal cord with the neurons that are involved in postural and locomotor reflexes. It is not known how the motoneurons form the appropriate peripheral and central reflex associations. It is therefore still necessary to survey the alternatives.
KeywordsSensory Nerve Neuromuscular Junction Motor Nerve Taste Cell Slow Muscle
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