Reflexes in cat ankle muscles after landing from falls.

Publisher Website
Google Scholar
Abstract
Electrical activity and length of ankle muscles were recorded by telemetry during free fall and landing in cats. After foot contact, there was a delay in onset of stretch of ankle extensors of between 8-11 ms. High-speed cinematography showed the delay to be associated with rapid initial dorsiflexion of the toes. Electromyograms (EMG) from lateral gastrocnemius increased in amplitude prior to landing. An early depression of lateral gastrocnemius EMG commenced at 8 ms after foot contact and was followed by a large peak of activity commencing some 8 ms after the first increase in lateral gastrocnemius length. local anaesthesia of theplantar cushion did not alter this pattern of response. The early inhibition of lateral gastrocnemius was attributed to the action on lateral gastrocnemius motoneurones of non-cutaneous afferents responding to the initial toe dorsiflexion. Additional autogenetic inhibition may also have contributed. The subsequent peak of EMG was at a latency consistent with a rapid stretch reflex and occurred some enough for the resulting active tension to contribute significantly to the extensor force during body deceleration.