Pharynx and Larynx
The innervation of pharynx and larynx has similarities to that of glabrous skin and oral mucosa. All possess an epithelium innervated by free endings and deeper layers innervated by a variety of complex endings. All possess two nerve nets or plexi. Oral, pharyngeal (newborn), and laryngeal mucosa possess chemosensory nerve endings or taste buds. Pharyngeal and laryngeal mucosa are different from skin and mouth, however, in that they have a much more richly innervated epithelium and a smaller number and variety of deep complex endings (Figs. 33A and 33B). In this respect, innervation of the pharynx and larynx resembles that of the airway of which they are both a part. However, the histology of the airway innervation has been little studied and its investigation hampered by the difficulty in differentiating the sensory innervation from the somatic motor and autonomic innervation (see Fillenz and Widdicombe, 1972). The rich epithelial innervation is common to all species, whereas there is a species hierarchy for deep receptors with the largest numbers and variety to be found in man. In general, the innervation of the pharynx and larynx is simpler than that of skin and mouth; the pattern resembles that of the skin of primitive aquatic vertebrates or the human fetus. However, this simpler innervation, especially of the mucosa overlying the base of the epiglottis and arytenoid cartilage, is fully developed ahead of oral mucosa and skin.
KeywordsRecurrent Laryngeal Nerve Myelinated Fiber Motor Fiber Superior Laryngeal Nerve Nodose Ganglion
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