Muscle tenderness and pain during movements are prominent symptoms associated with persistent jaw muscle pain. However, there is virtually no information on how trigeminal neurons respond to jaw movements (JM) or muscle palpation in the presence of muscle tissue injury or myositis. In this study, we investigated the effects of innocuous JM in the presence of acute masseteric inflammation on postsynaptic responses in the trigeminal brainstem nuclei by examining the expression of c-fos. In one group of rats, unilateral injections of an inflammatory substance, mustard oil (MO: 20%, 25 microl) were made into a masseter muscle. In another group, controlled and systematic JM were provided following MO injection. Three additional groups of rats were used to control for anesthetic, JM, and injection procedure. MO injected in the masseter muscle induced a high level of Fos protein expression in four principal trigeminal regions: the subnucleus caudalis (Vc), the ventral and dorsal regions of the Vc/Vi (subnucleus interpolaris) transition zone, and the paratrigeminal nucleus (PTN). Movements following MO injection consistently produced a significantly greater level of Fos expression in all these areas, especially in the Vc/Vi transition region and caudal Vc on the ipsilateral side. Importantly, movements also induced a significantly greater level of Fos expression in the caudal Vc on the contralateral side. The present results provide the first documentation that innocuous JM in the presence of muscle inflammation significantly increase the MO-induced c-fos expression in the trigeminal brainstem nuclei, which may explain the greater pain experienced during movement of inflamed or injured muscles.

This study suggests that, on the contrary to the findings in children and adolescents, BMI and gender should be taken into consideration when measuring the patency of upper airway in adults.

Objective: To study upper airway breathing in 115 children annually from 8 to 17 years of age with the hypothesis that upper airway respiratory needs increase steadily during growth and show sexual dimorphism. Material and Methods: To calculate nasal resistance, airflow rate (mL/s) and oronasal pressures (cmH 2 O) were measured during rest breathing in a seated position using the pressure-flow technique.Results: Median values of oronasal pressure ranged at different ages in girls from 0.88 to 1.13 and in boys from 0.92 to 1.44 cmH 2 O, being 0.95 and 0.93 cmH 2 O at the age of 17 years, respectively. The gender differences were statistically significant in four age groups (P , .05 by the Mann-Whitney test). Mean values of nasal resistance decreased from 8 to 17 years of age in girls from 4.0 (63.27) to 2.4 (62.30) and in boys from 3.3 (62.48) to 1.5 (60.81) cmH 2 O/L/s. However, there was an increase in resistance in 11-year-old girls and 12-year-old boys and at the age of 15 in both genders (P , .05 by paired t-test). Conclusions: Respiratory efforts stabilize oronasal pressure to maintain vital functions at optimal level. Nasal resistance decreased with age but increased temporarily at the prepubertal and pubertal phases, in accordance with other growth and possibly hormonal changes. When measuring upper airway function for clinical purposes, especially in patients with sleep apnea, asthma, allergies, cleft palate, or maxillary expansion, the measurements need to be compared with age-and genderspecific values obtained from healthy children. (Angle Orthod. 2016;86:610-616.)

Our results indicate that the increase in nasal airway size is not consistent during growth. Nasal airway size showed almost equal values for both genders in young children but was systematically larger in boys from 14 years of age on. The results refer that by 17 years of age nasal airway may not have reached adult size in males.

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