The interstitiospinal tract arises from the neurons of the interstitial nucleus (of Cajal) and descends in the medial longitudinal and the ventral funiculus of the spinal cord. It terminates in laminae 7-8 neurons, and also lamina 9 motor neurons of neck muscles (Watson and Harvey, 2009). In the cat, the interstitial nucleus projects bilaterally in the ventral funiculus as far as the sacral spinal levels (Nyberg-Hansen, 1996b), although some studies show projections only on the ipsilateral side (Castiglioni et al, 1978; Satoda et al, 2002). Spinal projections from this nucleus were also found in the rat and monkey.