Nerve supply of dilator pupillae is: (AIIMS May 2012)
1. The pupils are controlled by two muscles of Neuro ECTODERMAL ORIGIN-the sphincter pupillae and dilator pupillae.
2. The sphincter pupillae is supplied by the cholinergic nerves of the parasympathetic system through the oculomotor nerve.
3. Fibers start in the Edinger-Westphal nucleus.
4. The dilator pupillae is supplied by adrenergic fibers of the cervical sympathetic chain.
5. The balance of tone between these two antagonistic systems maintains the pupil in its normal size and under normal conditions the tone of sphincter pupillae is more than that of dilator pupillae.
6. Unequal sing of the two pupils known as anisocoria.
7. Hippus is a condition in which the oscillations of pupil are very large and can be easily seen. e.g. multiple sclerosis, normal person.