start stage end stage motor neuron spinal accessory motor neuron CL:0000741 ZFA:0009311 A motor neuron that is located in the cervical region of the spinal cord and selectively innervates the sternocleidmastoid or trapezius muscle. Unlike other motor neurons, they extend axons dorsally along lateral margins of the spinal cord. zebrafish_anatomy TAO:0009311 SACMN unknown adult