Inclusion Criteria:
* Diagnosis of cervical level spinal cord injury, either complete or incomplete; International Standards for Neurological Classification of Spinal Cord Injury (INCSCI) motor level of C4 through C8; American Spinal Injury Impairment Scale (AIS) grade A, B, C, or D; six months or more post-injury
* Biceps/brachialis/brachioradialis strength of 2/5 or higher on Manual Muscle Test
* Peripheral nerve innervation to upper extremity and trunk muscles, including a grade 3/5 or higher stimulated strength (Manual Muscle Test) in at least two of the following muscles in one arm: adductor pollicis, abductor pollicis brevis, flexor pollicis longus, extensor pollicis longus, extensor digitorum communis, flexor digitorum superficialis, flexor digitorum profundus, pronator quadratus, extensor carpi ulnaris, extensor carpi radialis brevis, extensor radialis longus, flexor carpi ulnaris, flexor carpi radialis, first dorsal interosseous; and in at least two of the following muscles: left/right gluteus maximus, left/right erector spinae, left/right quadratus lumborum,
* Age \> 16 years
* Medically stable - cleared for surgery
* Able and willing to take part in study
Exclusion Criteria:
* Currently pregnant (neuroprosthesis implantation delayed until no longer pregnant)
* Other neurological conditions (multiple sclerosis, diabetes with peripheral nerve involvement)
* History of coagulopathy, HIV, severe cardiopulmonary disease, severe bradycardia, severe autonomic dysreflexia, or chronic obstructive pulmonary disease.
* Active untreated infection such as decubitus ulcer, urinary tract infection, pneumonia
* Presence of other active implantable medical devices with unknown or untested interaction with the NNP implant
* Active implantable medical device (AIMD) such as a pacemaker or defibrillator, with the exception of the implanted stimulator-telemeter (IST) or implanted receiver stimulator (IRS) systems developed by the Cleveland Functional Electrical Stimulation Center
* Unhealed fractures that prevent functional use of arm or trunk
* Less than six months post-injury (neuroprosthesis implantation delayed until criteria met)
* Extensive upper extremity denervation (fewer than two stimulatable hand muscles and two stimulatable trunk muscles)
* Involvement in other ongoing clinical studies that exclude concurrent until criteria met)
* Disorder or condition that require MRI monitoring
* Mechanical ventilator dependency
* Progressive SCI In subjects who are undergoing bilateral implantation, subjects should not have a history of autonomic dysreflexia, hypertension, diabetes or any condition which requires frequent blood pressure monitoring or frequent venipuncture.
* Adverse interaction between system components and typical electromagnetic (EM) sources in subject's home and work environments, including wheelchair or other active implantable devices.
