Iris dilator muscle "musculus dilator pupillae", The "Nomina Anatomica" as authorized in 1895 in Basle and in 1935 in Jena used the full Latin expression. Iris dilator muscle The iris dilator muscle (pupil dilator muscle, pupillary dilator, radial muscle of iris, radiating fibers), is a smooth muscle of the eye, running radially in the iris and therefore fit as a dilator. The pupillary dilator consists of a spokelike arrangement of modified contractile cells called myoepithelial cells. These cells are stimulated by the sympathetic nervous system. When stimulated, the cells contract, widening the pupil and allowing for more light to pass through the eye.
Muscle coactivation ground. It is also believed to be important for postural control by stabilizing the spine. Muscle coactivation is absolutely necessary for learning a fine motor skill or for any activity involving stability. In order for muscle coactivation to occur, it must inhibit reciprocal innervation, which occurs when a muscle contracts and the synergist muscle relaxes. For muscle coactivation to occur, both the muscle and synergist muscle need to contract. Muscle coactivation is measured using a technique called electromyography(EMG). This is performed by using surface EMG that responds to electrical activity of the muscle through the skin. Electrical activity is only