Inclusion Criteria:
* Male or female, age \> 16 years.
* Cervical level spinal cord injury, as defined by:
1. International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) motor level of C1 through C7 and
2. American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade A, B, or C;
* Six months or more post-injury (neurostability);
* Neurologically stable following any nerve transfers affecting the upper extremity (typically, one year post surgery);
* Musculoskeletally and neurologically stable following any tendon transfers affecting the upper extremity (typically, 6-months).
* Peripheral nerve innervation to upper extremity muscles, including a grade 3/5 or higher Stimulated Manual Muscle Test (SMMT) strength in at least two of the following muscles in one arm:
1. Adductor Pollicus, Abductor Pollicus Brevis (AbPB), Flexor Pollicus Longus (FPL), Extensor Pollicus Longus (EPL)/Extensor Pollicus Brevis (EPB), Extensor Digitorum Communis (EDC), Flexor Digitorum Superficialis (FDS), Flexor Digitorum Profundus (FDP), Pronator Quadratus (PQ), Extensor Carpi Ulnaris (ECU), Extensor Carpi Radialis Brevis (ECRB), Extensor Carpi Radialis Longus (ECRL), Flexor Carpi Ulnaris (FCU), Flexor Carpi Radialis (FCR), First Dorsal Interosseous(1DI), triceps,
2. At least two of the grade 3/5 or higher excitable muscles must also have grade 2/5 or lower voluntary strength;
* Good proximal upper extremity strength as defined by biceps/brachialis/brachioradialis strength of 2/5 or higher on Manual Muscle Test on the side intended for implantation;
* Medically stable;
* Able to understand and provide informed consent.
Exclusion Criteria:
* Other neurological conditions (MS(multiple Sclerosis), diabetes with peripheral nerve involvement); Associated peripheral nerve / brachial plexus injury
* Progressive SCI;
* Co-existing cervical spine pathology (syrinx, unstable segment)
* Active implantable medical device (AIMD) such as a pacemaker or defibrillator;
* Active untreated infection such as pressure injury, urinary tract infection, pneumonia;
* History of coagulopathy, HIV, cardiopulmonary disease, bradycardia, poorly controlled autonomic dysreflexia, or chronic obstructive pulmonary disease that would preclude safe participation in the trial as determined by the investigator;
* Unhealed fractures that prevent functional use of arm;
* Extensive upper extremity denervation (fewer than two excitable hand muscles);
* Involvement in other ongoing clinical studies that exclude concurrent involvement in this study;
* Disorder or condition that requires MRI monitoring;
* Mechanical ventilator dependency;
* Currently pregnant (neuroprosthesis implantation delayed until no longer pregnant);
* Presence of disease that might interfere with participant safety, compliance, or evaluation of the condition under study;
* Other significant medical findings that, in the opinion of the investigator, preclude safe participation in the trial.
