Fetal anatomy of the upper pharyngeal muscles with special reference to the nerve supply: is it an enteric plexus or simply an intramuscular nerve?

Abstract

We examined pharyngeal nerve courses in paraffin-embedded sagittal sections from 10 human fetuses, at 25-35 weeks of gestation, by using S100 protein immunohistochemical analysis. After diverging from the glossopharyngeal and vagus nerves at the level of the hyoid bone, the pharyngeal nerves entered the constrictor pharyngis medius muscle, then turned upward and ran superiorly and medially through the constrictor pharyngis superior muscle, to reach either the levator veli palatini muscle or the palatopharyngeus muscle. None of the nerves showed a tendency to run along the posterior surface of the pharyngeal muscles. Therefore, the pharyngeal nerve plexus in adults may become established by exposure of the fetal intramuscular nerves to the posterior aspect of the pharyngeal wall because of muscle degeneration and the subsequent rearrangement of the topographical relationship between the muscles that occurs after birth.

A Case of Isolated Unilateral Glossopharyngeal Nerve Palsy

“…Based on a fetal study, SCM and palatopharyngeus (PP) are connected in fetal life; hence, their nerve should be common (based on Shimokawa's concept). 7,8 Thus, ischemia to the X-ph branch, being a common nerve, would also affect the PP presenting as hyper nasality, soft palate paresis, and nasal regurgitation unilaterally, which were all absent in our patient. Arterial ischemia of SCM is unlikely due to rich anastomosis between the arteries of this region.…”

“…5 The anatomy of the pharyngeal wall and the innervation are unclear, and several studies have revealed different innervation patterns in these muscles. [6][7][8] Even the physiology of the gag reflex is ambiguous. Few reports account for an afferent glossopharyngeal that synapses in the ipsilateral nucleus ambiguus and sends out its efferent via the vagus.…”

Review of the external carotid plexus: anatomy, function, and clinical manifestations

“…Previous cases have also identified communications between this plexus and other nerves. For example, cutaneous branches of the external carotid plexus in the cervical region were found intermingling with the supernumerary branch of the glossopharyngeal nerve as well as branches that originated from the vagus nerve [ 10 , 11 ].…”

Insertions of the striated muscles in the skin and mucosa: a histological study of fetuses and cadavers

“…The pharyngeal constrictor muscles surround the pharyngeal mucosa, but have an origin in the hard tissue and an insertion in the pharyngeal raphe. The levator veli palatini and stylopharyngeus muscles penetrate a ‘muscle tube’ of the constrictors and approach the mucosa [ 1 - 3 ]. Likewise, the levator veli palatini and uvulae muscles may approach the oral mucosa, because they are interdigitated in the soft palate [ 4 - 9 ].…”