Location of premotor neurons of the motor nuclei innervating craniocervical muscles in the mallard (Anas platyrhynchos L.).

Reticular premotor neurons of craniocervical muscles in the duck were localized with the retrograde tracer HRP and the anterograde tracer WGA-HRP. In the reticular formation neck premotor neurons were found in the gigantocellular reticular nucleus and in the ventromedial part of the parvocellular reticular nucleus rostral to the obex, and caudal to the obex in the nucleus centralis ventralis of the medulla. Results were compared with premotor areas of jaw muscles. The ventromedial part of the parvocellular reticular formation contains neck as well as jaw premotor neurons. This area may serve as the neural substrate for the coordination of neck and jaw movements.