Introduction. In some cases of hemiplegia the onset of yawning is associated w ith an involuntary raising of the paralyzed arm. Patients and method. Four obser vations of this movement,which is seldom described probably because it is mostly neglected, were made in the neurology unit of the University Hospital of Poitie rs. The descriptions were compared with other cases that have been published in the medical literature of the last 150 years, Cerebral imagery shows a lesion th at is most often localized on the internal capsule. After comparison with experi mental models in cats, it is proposed that the section of the cortico-neocerebe llum tract of the extra-pyramidal system disinhibits the spino-archeocerebellum t ract, enabling a motor stimulation of the arm by the lateral reticular nucleus, which harmonises central respiratory and locomotor rhythms. Results and conclusi on. Some subcortical structures, that are phylogenetically more ancient, thus di sinhibit regained autonomy in the homeostasis process associating the massive in spiration of yawning -a form of reflex behavior that stimulates vigilance-with a motor control that is active during locomotion. For this phenomenon we coined the term “parakinesia brachialis oscitans”. Introduction. In some cases of hemiplegia the onset of yawning is associated w ith an involuntary raising of the paralyzed arm. Patients and method. Four obser vations of this movement, which is seldom described probably because it is mostly neglected, were made in the neurology unit of the University Hospital of Poitie rs. The descriptions were compared with other cases that have been published in the medical literature of the last 150 years, Cerebral imagery shows a lesion th at is most often localized on the internal capsule. After comparison with experi mental models in cats, it is proposed that the section of the cortico-neocerebe llum tract of the extra-pyramidal system disinhibits the spino-archeocerebellum t ract, enabling a motor stimulation of the arm by the lateral reticular nucleus, which harmonises central respiratory and Results and conclusi on. Some subcortical structures, that are phylogenetically more ancient, thus di sinhibit regained autonomy in the homeostasis process associating the massive in spiration of yawning -a form of reflex behavior that stimulates vigilance-with a motor control that is active during locomotion. For this phenomenon we coined the term “parakinesia brachialis oscitans.”