New Measurement Techniques of Surface Electromyographic Signals in Rest Position for Application in the Ophthalmological Field

Abstract

The Stomatognatic apparatus is a component of the craniomandibular system, and it represents an entryway to external stimuli: relationship among occlusion, masticatory muscle system (Murch, 1974; Oddsson, 1989) and head posture (Barber & Sharpe, 1988) have been recently confirmed. Proprioception messages from the neck muscles are integrated in the central nervous system and contribute to control balance and body orientation. Centripetal impulses from neck proprioceptors cooperate with the labyrinth impulses to promote oculomotor muscular activity through the cervical–vestibular–ocular reflex (Ito, 1995). Some important encephalic nuclei (trigeminal nuclei, oculomotor nuclei, vestibular nuclei, accessorial nerve nuclei) are integrated in the medial longitudinal fasciculus. Ocular proprioceptive receptors send afferent signals to trigeminal and cuneate nuclei. The anatomic and physiologic links of these anatomical structures imply a co-ordinated integration of proprioceptive ocular and stomatognathic afferences. The ocular system and the stomatognathic one are anatomically and physiologically connected. Vision plays an important role in the multi-sensorial process of postural stabilisation: among visual inputs, the postural one allows to draw a moving object ocular nuclei control the eye position in the orbit; the ocular nuclei send fibers to nuclei which control neck and head movements and receive afferences from vestibular nuclei. It has been observed that a modification of ocular proprioception modifies head and body posture (Donaldson & Knox, 1991; Buisseret-Delmas & Buisseret, 1990; Schmid et al., 1981). Ocular proprioception is linked with stomatognathic muscular system: neuromuscular spindles and myotendinous receptors (Rose et al., 1991; Lukas et al., 1994; Rose & Abrahams, 1975) of extraocular muscles send afferences to trigeminal and cuneate nuclei (Porter, 1986). Moreover oculomotor, vestibular, trigeminal and accessorial nerve nuclei are connected through the medial longitudinal fasciculus. The role of trigeminal afferences on tonic-postural regulation has been underlined too (Meyer & Baron, 1976) Several studies supported anatomical linkage between stomatognathic and ocular systems. Patients with Temporomandibular disorders (TMD) and this prevalence increase in those patients with head, neck, and shoulder pain. A similar association has been found in children with a mandibular functional lateral-deviation respect to healthy subjects in