What excites skeletal muscles and inhibits cardiac muscle?

Excitation

* Skeletal muscle: Acetylcholine (ACh) released from motor neurons

* Cardiac muscle: Calcium ions (Ca2+) released from the sarcoplasmic reticulum

Inhibition

* Skeletal muscle: None

* Cardiac muscle: Hyperpolarization of the cell membrane, which can be caused by a number of factors, including the release of acetylcholine from parasympathetic nerves