the nucleus ambiguus (literally "ambiguous nucleus") is a group of large motor neurons, situated deep in the medullary reticular formation named by jacob clarke. the nucleus ambiguus contains the cell bodies of neurons that innervate the muscles of the soft palate, pharynx, and larynx which are associated with speech and swallowing. as well as motor neurons, the nucleus ambiguus contains preganglionic parasympathetic neurons which innervate postganglionic parasympathetic neurons in the heart.