Jaw reflexes and masseter electromyograms were studied in five patients with mesencephalic and 11 patients with pontine lesions, vascular or tumorous in nature. In the former group jaw reflexes were abnormal, being delayed or absent, whereas masseter electromyograms were normal. In the latter group, both jaw reflexes and masseter EMG, showing denervation, were abnormal in six and both normal in...

The aim of this study was to clarify the normal function of the inferior head of the human lateral pterygoid muscle (IHLP). The hypothesis was that an important function of the IHLP is in the fine control of horizontal jaw movements. The activities of 99 single motor units (SMUs) were recorded from IHLP (22 recordings from 16 subjects). Most recording sites were identified by computer tomograph...

The present study considers the muscle impedance control of upper lip-jaw coordination for jaw mechanical perturbations during bilabial utterances. When we perturbed jaw movement for the / / utterance in the carrier sentences of ”kono a a a mitai”, labial distance was recovered quickly by the downward shift of the upper lip [8]. Initial downward shift (40ms after the load onset) of the upper li...

Common marmosets (Callithrix jacchus) generate wide jaw gapes when gouging trees with their anterior teeth to elicit tree exudate flow. Closely related cotton-top tamarins (Saguinus oedipus) do not gouge trees but share similar diets including exudates. Maximizing jaw opening theoretically compromises the bite forces that marmosets can generate during gouging. To investigate how jaw-muscle arch...

Sexual dimorphism is common in nature and has the potential to increase intraspecific variation in performance and patterns of resource use. We sought to determine whether anadromous threespine stickleback, Gasterosteus aculeatus, exhibit sexual dimorphism in feeding kinematics. We filmed four males and four females consuming live prey in a total of 51 sequences filmed at 500 Hz, then tested fo...

Vertebrates have achieved great evolutionary success due in large part to the anatomical diversification of their jaw complex, which allows them to inhabit almost every ecological niche. While many studies have focused on mechanisms that pattern the jaw skeleton, much remains to be understood about the origins of novelty and diversity in the closely associated musculature. To address this issue...

The purpose of this study is to evaluate whether the range of motion exercise of the temporo-mandibular joint (jaw ROM exercise) with a hot pack and massage of the masseter muscle improve biting disorder in Duchenne muscular dystrophy (DMD). The subjects were 18 DMD patients (21.3+/- 4.1 years old). The jaw ROM exercise consisted of therapist-assisted training (2 times a week) and self-training...

PURPOSE The authors' general aim is to use biomechanical models of speech articulators to explore how possible variations in anatomical structure contribute to differences in articulatory strategies and phone systems across human populations. Specifically, they investigated 2 issues: (a) the link between lip muscle anatomy and variability in lip gestures and (b) the constraints of coupled lip/j...

Reflex responses in jaw-opening muscles can be evoked when a brittle object cracks between the teeth and suddenly unloads the jaw. We hypothesized that this reflex response is flexible and, as such, is modulated according to the instructed goal of biting through an object. Study participants performed two different biting tasks when holding a peanut half stacked on a chocolate piece between the...

We describe the organisation of the palate in a specimen of the Mexican axolotl (Ambystoma mexicanum), which spontaneously started metamorphosis in an advanced age after several breeding cycles, but had not yet completed transformation at an age of > 7 years when it was euthanized. The palate shows a mosaic of paedomorphic (absence of the edentate vomerine plate, monocuspid pedicellate teeth) a...