Purpose of the study: Spastic hypertony of the upper limb produces pronation of the forearm with flexion of the wrist and fingers. Treatment is generally based on injections of botulinum toxin and sometimes on selective neurotomy.

Material and methods: In order to achieve better selection of the motor branches innervating the muscles requires a precise knowledge of the extramuscular innervation. Similarly, for botulinum toxin, injections must be made as close as possible to zones with the greatest density of intramuscular nerve endings, considered as the zones having the greatest number of neuromuscular junctions. Knowledge of these zones is currently insufficient. We therefore conducted a macroscopic then microscopic dissection of the muscles of the ventral forearm in 30 specimens to study extra- and intra-muscular innervations and the distributions of the nerve endings.

Results: Surface maps were drawn to describe the precise localization of the motor branches for each muscle. These maps were designed as guides for surgical approaches for selective neurotomy. Then for each muscle, the zones with the greatest density of nerve endings were delimited in segments which could be used to define optimal zones of injection of botulinum toxin.