Location of motoneurons innervating soft palate, pharynx and upper esophagus. Anatomical evidence for a possible swallowing center in the pontine reticular formation. An HRP and autoradiographical tracing study.

Retrograde HRP studies indicated that motoneurons innervating soft palate and pharynx are located in especially the dorsal group of the nucleus ambiguus, while motoneurons innervating upper esophagus and cricothyroid muscles are located in the retrofacial nucleus, the most rostral part of the nucleus ambiguus. Autoradiographic tracing techniques revealed that in the caudal pontine tegmentum an area is located just dorsal to the superior olivary complex, that projects contralaterally to the ventral part of the trigeminal motor nucleus, the dorsal group of the nucleus ambiguus and the ventral part of the hypoglossal nucleus. In these areas motoneurons are located innervating the mylohyoid, soft palate, pharynx and geniohyoid muscles respectively. Since these muscles are all involved in swallowing, a possible involvement of this pontine tegmental area in swallowing is discussed.