the circular muscle of the iris uses which parasympathetic receptor
Iris sphincter muscle It is controlled by parasympathetic fibers of the muscarinic acetylcholine receptor (M3) that originate from the Edinger-Westphal nucleus, travel along the oculomotor nerve (CN III), synapse in the ciliary ganglion, and then enter the eye via the short ciliary nerves.[citation needed]. The short ciliary nerves then run forward and pierce the sclera at the back of the eye, traveling between the sclera and the choroid to innervate the iris sphincter muscle.
Engagement ring In Western countries, it is customarily worn on the left hand ring finger, though customs vary across the world.
Iris (anatomy) The iris consists of two layers: the front pigmented fibrovascular known as a stroma and, beneath the stroma, pigmented epithelial cells.
Bundle of His These specialized muscle fibers in the heart were named after the Swiss cardiologist Wilhelm His, Jr., who discovered them in 1893.[3][4]