The supraspinalis nucleus, cut off by the pyramidal junction , is the apex (uppermost part) of the inner motor neuron group of the spinal cord and borders upwards to (passes into) the nucleus nervi hypoglossia.
The supraspinalis nucleus is encountered in the transition zone between spinal cord segment C1 and the medulla. The axons of the motor neuron group leave the spinal cord and form the front root C1.