Exponential increases of available computational resources, miniaturization, and sensors, are enabling the development of digital musical instruments that use non-conventional interaction paradigms and interfaces. This scenario opens up new opportunities and challenges in the creation of accessible instruments to include persons with disabilities into music practice. This work focuses in particular on instruments dedicated to people who can not use limbs, for whom the only means for musical expression are the voice and a small number of traditional instruments. First, a modular and adaptable conceptual framework is discussed for the design of accessible digital musical instruments targeted at performers with motor impairments. Physical interaction channels available from the neck upwards (head, mouth, eyes, brain) are analyzed in terms of potential and limitations for musical interaction. Second, a systematic survey of previously developed instruments is presented: each is analyzed in terms of design choices, physical interaction channels and related sensors, mapping strategies, performer interface and feedback. As a result of this survey, several open research directions are discussed, including the use of unconventional interaction channels, musical control mappings, multisensory feedback, design, evaluation, and adaptation. INDEX TERMS Accessibile interfaces, Music technology, Digital musical instruments, Inclusive music practice VOLUME ...