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Neurosci Lett. 2017 Feb 15;640:1-5. doi: 10.1016/j.neulet.2017.01.016. Epub 2017 Jan 9.

Searching for proprioceptors in human facial muscles.

Author information

1
Departamento de Morfología y Biología Celular, Grupo SINPOS, Sección de Anatomía y Embriología Humana, Universidad de Oviedo, Oviedo, Spain; Servicio de Cirugía Máxilofacial, Hospital Universitario Central de Asturias, Oviedo, Spain.
2
Dipartimento di Science Veterinarie, Sezione di Anatomia, Università di Messina, Messina, Italy.
3
Servicio de Cirugía Máxilofacial, Hospital Universitario Central de Asturias, Oviedo, Spain; Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Área de Odontología, Universidad de Oviedo, Oviedo, Spain.
4
Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Área de Odontología, Universidad de Oviedo, Oviedo, Spain; Instituto Asturiano de Odontología, Oviedo, Spain.
5
Departamento de Morfología y Biología Celular, Grupo SINPOS, Sección de Anatomía y Embriología Humana, Universidad de Oviedo, Oviedo, Spain; Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago de Chile, Chile. Electronic address: javega@uniovi.es.

Abstract

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception.

KEYWORDS:

Facial muscles; Mechanoproteins; Proprioceptors; Sensory corpuscle-like structures

PMID:
28082150
DOI:
10.1016/j.neulet.2017.01.016
[Indexed for MEDLINE]

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