Pronounced /ˈæ.tʰoʊ.ni/

In medicine

Medicine

Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, atony (or "atonia", or "atonic") refers to a muscle

Muscle

Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

 that has lost its strength. It is frequently associated with the conditions Atonic seizure

Atonic seizure

Atonic seizures , are a type of seizure. They consist of a brief lapse in muscle tone that are caused by temporary alterations in brain function. The seizures are brief - usually less than fifteen seconds. They begin in childhood and may persist into adulthood...

, atonic colon, uterine atony

Uterine atony

Uterine atony is a loss of tone in the uterine musculature. Normally, contraction of the uterine muscle compresses the vessels and reduces flow. This increases the likelihood of coagulation and prevents bleeds. Thus, lack of uterine muscle contraction can cause an acute hemorrhage...

, gastrointestinal atony (occurs postoperatively) and choreatic atonia.

Atony can also refer to the paralyzed or extremely relaxed state of skeletal muscles in rapid eye movement sleep (REM sleep) in most warm-blooded animals.