Human being's care and medicine as a science require that the knowledge and experience of the individual can be shared and enriched by comparison with many others. This is the goal of the authors - doctors belonging to different specialist fields (neurology, physical medicine and rehabilitation, radiology) - who have recognized the common need to communicate their experience in the treatment of muscle hyperactivity through botulinum toxin injection, hoping that the reverberation of sharing may increase one's own and others' knowledge. The authors describe the ultrasound-guided botulinum toxin injection for more than 80 muscles of the neck, of the trunk and of the upper limb and lower limb. For each muscle the handbook provides the description of the function, origin, insertion, innervation as well as injection sites and dosage. The collection of images is particularly rich (more than 300), including anatomical drawings, ultrasound images and clinical photographs.