Neuroanatomical considerations of palatal muscles: tensor and levator veli palatini.

The tensor veli palatini (TVP) and levator veli palatini (LVP) muscles are intimately associated with the soft palate and knowledge of their anatomy and physiology is essential for palatoplasty. Controversy regarding the function and innervation of these muscles still exists. The purpose of this study was to identify the location of motoneurons within the brainstem which innervate the TVP and LVP using the current neuroanatomical tracing technique of retrograde axonal transport of horseradish peroxidase (HRP). HRP was injected into each of these muscles in adult cats. Following a twenty-four hour survival the animals were sacrificed, the brain removed and processed using tetramethyl benzidene . TVP motoneurons were located in the rostral two-thirds of the ventromedial division of the trigeminal motor nucleus. LVP motoneurons were located in the rostral 2 mm of the nucleus ambiguus ipsilaterally and to a lesser extent contralaterally as well as in the retrofacial nucleus ipsilaterally. Our study has addressed neuroanatomical aspects essential to an understanding of the structure and function of the palatal muscles. Unraveling the central connections of the TVP, LVP motoneurons may clarify understanding of such complex functions as swallowing, sucking, blowing and speech.