Early (ES1) and late (ES2) exteroceptive suppression periods elicited by electrical stimulation of the labial commissure during teeth-clenching were recorded over the temporalis muscle in 45 headache patients (25 tension headaches and 20 migraines) and 22 controls. Mean duration of ES2 for single shocks was significantly reduced in tension headache when compared with migraine or controls. At a stimulation rate of 2 Hz, ES2 was abolished in 40% of tension headache sufferers, but in none of the migraineurs. EMG analysis of temporalis late exteroceptive suppression might be a helpful diagnostic tool in functional headaches. Reduction of ES2 suggests that there is deficient activation or excessive inhibition of pontobulbar inhibitory interneurons which receive a strong input from limbic structures. ES2 might thus represent an interface between psychogenic and myogenic factors putatively involved in the pathogenesis of tension headache.

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On the basis of a simple example, it is shown that unrealistic “numerical” boundary layers can develop along solid boundaries in models using a certain type of staggered computational grid. In this particular case the artifact can be ascribed to the discretization of the Coriolis term along the boundary combined with the inadequacy of the boundary condition. As a consequence of that error, the solution of a three‐dimensional numerical model is found to converge toward an incorrect steady state (the residual mean flow does not vanish as it should). A straightforward correction, called the “wet‐points‐only” method, is proposed. The procedure consists of eliminating the boundary points from the evaluation of the Coriolis term. The wet‐points‐only method is shown to also affect the results obtained with a two‐dimensional (vertically integrated) model. In this case, however, the implementation of the procedure usually downgrades rather than improves the numerical solution. For schemes wherein the velocity components are not calculated at the same locations, care must be taken in the evaluation of any term that couples the two components of the momentum equation.