Diastasis
Tetany is the medical term meaning inability to relax the muscles.
Costochondritis is inflammation of the muscles in the ribs
Colic is the medical term meaning spasm of the visceral muscles.
intercostal muscles - from inter meaning 'between', and costa meaning 'rib'
rigormortis
Myologist is the term meaning specialist in the study of muscles, but an orthopedist is the typical specialist physician who treats muscle problems.
Tetany is the medical term continuous spasm of muscles; tetany may result from hypocalcemia.
Contracture or contraction
The medical term for muscles located within an organ is "smooth muscles" or "involuntary muscles." These muscles are responsible for the involuntary movements of internal organs, such as those in the digestive system, blood vessels, and uterus.
Achalasia
Capsulitis
heart block