The zygomaticus promotes smiling.

The flexor carpi radialis can be found in the superficial posterior compartment of the forearm because it originates on the humerus. 

Epithelial 

tissue surrounds and protect muscular

tissue.

The vastus medialis is in the medial compartment of the thigh

What molecules form

the thick filaments within muscle?

A deficiency of acetylcholine receptors leads to muscle paralysis in myasthenia gravis.

A tic is a

rhythmic, involuntary, purposeless contraction that produces quivering or

shaking.

The process of engaging more motor units to increase the strength of a muscle contraction is called

What happens to a

muscle during an isometric contraction?

What happens when acetylcholine stimulates its receptors in the neuromuscular junction?