Cervical PlexusNerve BlockSubmandibular Gland DiseasesAnesthetics, LocalAnatomic LandmarksFasciaChoroid PlexusEndarterectomy, CarotidAnesthesia, GeneralAnesthesiaBrachial PlexusAmidesBupivacaineAnesthesia, LocalAnesthesia, SpinalAnesthesia, EpiduralAnalgesicsAnesthesia, ConductionAnesthesia, InhalationAnesthesia, IntravenousMyenteric Plexus