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.
Clay-colored sparrow Clay-colored sparrow The clay-colored sparrow or clay-coloured sparrow ("Spizella pallida") is a small sparrow of North America. Adults have light brown upperparts and pale underparts, with darker streaks on the back. They have a pale crown stripe on a dark brown crown, a white line over the eyes, a dark line through the eyes, a light brown cheek patch and brown wings with wing bars. The short bill is pale with a dark tip and the back of the neck is grey; they have a long tail. Non-breeding adults and immature resemble chipping sparrows and Brewer's sparrows; they often form