Identification and localization of the motor nuclei and sensory projections of the glossopharyngeal, vagus, and hypoglossal nerves of the cockatoo (Cacatua roseicapilla), cacatuidae

Abstract

Horseradish peroxidase (HRP) has been applied to the proximal severed ends of glossopharyngeal (N IX), vagus (NX), and hypoglossal (N XII) cockatoo in order to localize the motoneurons and sensory projections of these nerves which are involved in the control of the bird's feeding and phonatory behaviors. Application of HRP to N IX labeled four rhombencephalic nuclei: (1) a large-celled, retrofacial nucleus supplying M. geniohyoideus, the major tongue extensor; (2) a dorsal nucleus composed of medium-sized cells, projecting to most branches of N IX; (3) a ventrolateral nucleus supplying, amongst other structures, the floor of the pharynx and larynx; and (4) a ventral portion of the dorsal motor nucleus of the vagus. Neurons labeled by application of HRP to the cervical vagus comprise the classically defined dorsal motor nucleus and a ventrolateral medullary nucleus which is coextensive with that of the glossopharyngeus: together they probably constitute a nucleus ambiguus. Application of HRP to hypoglossal branches labeled a large nucleus intermedius (IM) and neurons ventral, ventrolateral, and caudal to it. The rostral third of IM supplies the lingual muscles, the caudal two-thirds the tracheosyringeal muscles. Many labeled neurons were found in the "jugular" ganglion following HRP treatment of each of the three nerves, especially N IX and N XII, which innervate the tongue. Central projections of these neurons are to nuclei of the descending trigeminus and to largely nonoverlapping portions of the principal trigeminal nucleus. It is hypothesized that these afferents provide sensory information necessary for the efficient processing and passage of food in the mouth.

Revised nomenclature for avian telencephalon and some related brainstem nuclei

“…In the Karten and Hodos pigeon brain atlas, a population of motoneurons located ventral to the dorsal motor nucleus of the vagus nerve and the nucleus intercalatus at levels straddling the obex was named the nucleus intermedius, following the practice of earlier workers (Ariëns- Kappers et al, 1936). Because this nucleus is now known to innervate tongue, tracheal, and syringeal muscles via the lingual and tracheosyringeal branches of the 12th nerve (Hillebrand, 1971;Nottebohm et al, 1976;Wild and Zeigler, 1980;Wild, 1981;Eden and Correia, 1982;Youngren and Phillips, 1983;Vicario and Nottebohm, 1988;Dubbeldam and Bout, 1990;Wild, 1990), the Nomenclature Forum decided to formally endorse the renaming of the nucleus intermedius of Karten and Hodos as the hypoglossal nucleus, or nXII (Table 1, Fig. 3A).…”

“…A population of motoneurons ventral to the nucleus intermedius of Karten and Hodos (1967) and abutting the lateral edge of the medial longitudinal fasciculus was identified in their atlas as the hypoglossal nucleus. This group of motoneurons is made up of dorsomedial and ventrolateral clusters, both of which are now known to innervate upper neck muscles, but not the tongue (Wild, 1981;Eden and Correia, 1982;Watanabe and Ohmori, 1988;Horster et al, 1990;Zijlstra and Dubbeldam, 1994). This cell group is separate from an upper cervical spinal cord nucleus from which the accessory nerve arises (Beccari, 1943;Hillebrand, 1975;Wild, 1981;Zijlstra and Dubbeldam, 1994).…”

“…This group of motoneurons is made up of dorsomedial and ventrolateral clusters, both of which are now known to innervate upper neck muscles, but not the tongue (Wild, 1981;Eden and Correia, 1982;Watanabe and Ohmori, 1988;Horster et al, 1990;Zijlstra and Dubbeldam, 1994). This cell group is separate from an upper cervical spinal cord nucleus from which the accessory nerve arises (Beccari, 1943;Hillebrand, 1975;Wild, 1981;Zijlstra and Dubbeldam, 1994). The Nomenclature Forum therefore decided to rename this cell group formally as the nucleus supraspinalis, the name that had been employed in several studies subsequent to the publication of the Karten and Hodos atlas (Hillebrand, 1975;Wild and Zeigler, 1980;Wild, 1981) (Table 1, Fig.…”

“…This cell group is separate from an upper cervical spinal cord nucleus from which the accessory nerve arises (Beccari, 1943;Hillebrand, 1975;Wild, 1981;Zijlstra and Dubbeldam, 1994). The Nomenclature Forum therefore decided to rename this cell group formally as the nucleus supraspinalis, the name that had been employed in several studies subsequent to the publication of the Karten and Hodos atlas (Hillebrand, 1975;Wild and Zeigler, 1980;Wild, 1981) (Table 1, Fig. 3A).…”

The Neural Substrate for ‘Learned’ and ‘Nonlearned’ Activities in Birds: A Discussion of the Organization of Bulbar Reticular Premotor Systems with Side-Lights on the Mammalian Situation

“…In birds, the laryngeal musculature is innervated by the nucleus ambiguus [Wild, 1981]; so far, there is no evidence that this center receives a direct input from the dorsomedial cell group of the intercollicular nucleus. A further difference between birds and mammals, of course, concerns the ventilation mechanism of the lungs.…”