Vascular tunic of eyeball(middle ■Iris虹膜 a Thin contractile membrane anterior to ciliary body, with a central opening the pupil瞳孔 o Contains sphincter pupillae瞳孔括约肌( circular fibers) and dilator pupillae 瞳孔开大肌( radial fibers) o Cornea and iris meet to form the iridocorneal angle虹膜角膜角Vascular tunic of eyeball (middle) ◼ Iris 虹膜 ❑ Thin contractile membrane anterior to ciliary body, with a central opening, the pupil 瞳孔 ❑ Contains sphincter pupillae 瞳孔括约肌(circular fibers) and dilator pupillae 瞳孔开大肌(radial fibers) ❑ Cornea and iris meet to form the iridocorneal angle 虹膜角膜角