The first phase, an investigator training phase, is aimed to become familiar with the Siemens Acuson S2000 after the upgrade. The two investigators will train with 5 healthy volunteers. In the second phase inter-observer variability of the ultrasound and Ashworth scale will be assessed by having healthy volunteers and patients evaluated by the different investigators. Since spasticity does fluctuate throughout the day, subjects will be consecutively assessed for inter-observer variability and within a few hours or around the same time the following day (depending on patient availability) for intra-observer variability. Each investigator will do the Ashworth scale independent of the other. Each investigator will do the ultrasound independent of the other. In the third phase, we will assess patients and volunteers to reach the sample size that a power analysis suggested that we would need to measure differences between patients with spasticity and controls.