Inhibition of the target phenomenon in tenotomized rabbit muscle by medullary lesions

Target fibres were demonstrated in the gastrocnemius muscles following section of the Achilles tendon of two rabbits. In five other animals with tenotomized gastrocnemius muscles, a subarachnoid phenol block of the lumbar and sacral spinal cord was performed. Large and small medullary lesions inhibited the occurrence of target fibres in the tenotomized muscles, the smallest one being neurolysis of the dorsal roots. This final experiment suggests that the target phenomenon is the morphological expression of an increased stretch sensitivity of the tenotomized muscle.