Innervation of human soft palate muscles.

Our objective was to determine the branching and distribution of the motor nerves supplying the human soft palate muscles. Six adult specimens of the soft palate in continuity with the pharynx, larynx, and tongue were processed with Sihler's stain, a technique that can render large specimens transparent while counterstaining their nerves. The cranial nerves were identified and dissection followed their branches as they divided into smaller divisions toward their terminations in individual muscles. The results showed that both the glossopharyngeal (IX) and vagus (X) nerves have three distinct branches, superior, middle, and inferior. Only the middle branches of each nerve contributed to the pharyngeal plexus to which the facial nerve also contributed. The pharyngeal plexus was divided into two parts, a superior innervating the palatal and neighboring muscles and an inferior innervating pharyngeal constrictors. The superior branches of the IX and X nerves contributed innervation to the palatoglossus, whereas their middle branches innervated the palatopharyngeus. The palatoglossus and palatopharyngeus muscles appeared to be composed of at least two neuromuscular compartments. The lesser palatine nerve not only supplied the palatal mucosa and palatine glandular tissue but also innervated the musculus uvulae, palatopharyngeus, and levator veli palatine. The latter muscle also received its innervation from the superior branch of X nerve. The findings would be useful for better understanding the neural control of the soft palate and for developing novel neuromodulation therapies to treat certain upper airway disorders such as obstructive sleep apnea.

Palatoglossus coupling in selective upper airway stimulation.

OBJECTIVES/HYPOTHESIS: Selective upper airway stimulation (sUAS) of the hypoglossal nerve is a useful therapy to treat patients with obstructive sleep apnea. Is it known that multiple obstructions can be solved by this stimulation technique, even at the retropalatal region. The aim of this study was to verify the palatoglossus coupling at the soft palate during stimulation. STUDY DESIGN: Single-center, prospective clinical trail. METHODS: Twenty patients who received an sUAS implant from April 2015 to April 2016 were included. A drug-induced sedated endoscopy (DISE) was performed before surgery. Six to 12 months after activation of the system, patients' tongue motions were recorded, an awake transnasal endoscopy was performed with stimulation turned on, and a DISE with stimulation off and on was done. RESULTS: Patients with a bilateral protrusion of the tongue base showed a significantly increased opening at the retropalatal level compared to ipsilateral protrusions. Furthermore, patients with a clear activation of the geniohyoid muscle showed a better reduction in apnea-hypopnea index. CONCLUSIONS: A bilateral protrusion of the tongue base during sUAS seems to be accompanied with a better opening of the soft palate. This effect can be explained by the palatoglossal coupling, due to its linkage of the muscles within the soft palate to those of the lateral tongue body. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:E378-E383, 2017.

The innervation of the soft palate muscles involved in cleft palate: a review of the literature.

OBJECTIVE: Surgical techniques to obtain adequate soft palate repair in cleft palate patients elaborate on the muscle repair; however, there is little available information regarding the innervation of muscles. Improved insights into the innervation of the musculature will likely allow improvements in the repair of the cleft palate and subsequently decrease the incidence of velopharyngeal insufficiency. We performed a literature review focusing on recent advances in the understanding of soft palate muscle innervation. MATERIAL AND METHODS: The Medline and Embase databases were searched for anatomical studies concerning the innervation of the soft palate. RESULTS: Our literature review highlights the lack of accurate information about the innervation of the levator veli palatini and palatopharyngeus muscles. It is probable that the lesser palatine nerve and the pharyngeal plexus dually innervate the levator veli palatini and palatopharyngeus muscles. Nerves of the superior-extravelar part of the levator veli palatini and palatopharyngeus muscles enter the muscle form the lateral side. Subsequently, the lesser palatine nerve enters from the lateral side of the inferior-velar part of the levator veli palatini muscle. This knowledge could aid surgeons during reconstruction of the cleft musculature. The innervation of the tensor veli palatini muscle by a small branch of the mandibular nerve was confirmed in all studies. CONCLUSION: Both the levator veli palatini and palatopharyngeus muscles receive motor fibres from the accessory nerve (through the vagus nerve and the glossopharyngeal nerve) and also the lesser palatine nerve. A small branch of the mandibular nerve innervates the tensor veli palatini muscle. CLINICAL RELEVANCE: Knowledge about these nerves could aid the cleft surgeon to perform a more careful dissection of the lateral side of the musculature.

Central and peripheral motor drive to the palatal muscles.

AIM OF THE STUDY: To characterize the motor command of the soft palate muscles using a magnetic stimulation technique. MATERIAL AND METHODS: Motor evoked potentials (MEPs) were recorded in 10 right-handed and 5 left-handed subjects at the midline of the palate or on the right or left hemipalate to peripheral and cortical magnetic stimulation. RESULTS: Mean palatal MEP amplitude ranged from 0.06 to 0.26mV to peripheral stimulation and from 0.36 to 1.09mV to cortical stimulation. In hemipalate recordings, MEPs to peripheral stimulation had greater amplitude when recorded ipsilaterally to the stimulation side, whereas MEPs to cortical stimulation were symmetrical. In midline recordings, right-handed subjects showed greater palatal MEP amplitude to right (rather than left) peripheral stimulation and to left (rather than right) cortical stimulation. Mean palatal MEP latency ranged from 4.0 to 4.1ms to peripheral stimulation and from 9.0 to 10.2ms to cortical stimulation; mean central conduction time ranged from 4.9 to 6.2ms. CONCLUSION: Palatal MEPs were easily and reliably obtained, including selective responses in each hemipalate. A bilateral cortical command of the palate is supported by our results, with a possible predominant motor drive from the left hemisphere in right-handed subjects.

Three-dimensional imaging of palatal muscles in the human embryo and fetus: Development of levator veli palatini and clinical importance of the lesser palatine nerve.

BACKGROUND: After palatoplasty, incomplete velopharyngeal closure in speech articulation sometimes persists, despite restoration of deglutition function. The levator veli palatini (LVP) is believed to be significantly involved with velopharyngeal function in articulation; however, the development and innervation of LVP remain obscure. The development of LVP in human embryos and fetuses has not been systematically analyzed using the Carnegie stage (CS) to standardize documentation of development. RESULTS: The anlage of LVP starts to develop at CS 21 beneath the aperture of the auditory tube (AT) to the pharynx. At CS 23, LVP runs along AT over its full length, as evidenced by three-dimensional image reconstruction. In the fetal stage, the lesser palatine nerve (LPN) is in contact with LVP. CONCLUSIONS: The positional relationship between LVP and AT three-dimensionally, suggesting that LVP might be derived from the second branchial arch. Based on histological evidence, we hypothesize that motor components from the facial nerve may run along LPN, believed to be purely sensory. The multiple innervation of LVP by LPN and pharyngeal plexus may explain the postpalatoplasty discrepancy between the partial impairment in articulation vs. the functional restoration of deglutition. That is, the contribution of LPN is greater in articulation than in deglutition.

Palatoglossus muscle neuroanatomy: a review

The palatoglossus muscle is classically described as an extrinsic muscle of the tongue. However, this descriptionis not consensus among the researchers, is one that sometimes it is not considered a muscle of the tongue.Thus, the objective of this study is to discuss some neuroanatomical aspects of palatoglossus muscle that mayhelp explain this aspect. Furthermore, this study shall be useful for clinicians, surgeons and academics thatmanipulate and keep particular interest for this anatomical site.

[Denervation change of tensor veli palati in obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To explore the denervation change of Tensor Veli Palati in patients with OSAHS by determine the mRNA and protein expression of NCAM. METHOD: The OSAHS group was consisted of 30 OSAHS patients and the normal control group was consisted of 10 chronic tonsillitis patients without OSAHS. Real-time quantitative RT-PCR and Western blot methods were used to determine the NCAM expression in specimens. RESULT: (1) The mRNA and protein expression level of NCAM in the OSAHS group increased significantly compared with that in control group (P < 0.05). (2) There was positive correlation between AHI and the protein expression level of NCAM in the OSAHS group (r = 0.803, P < 0.01). CONCLUSION: These results indicate that the denervation change of tensor veli palati appear in OSAHS patients, and the severity of OSAHS are relevant with the degree of denervation.