Terminology for Disorders of Muscle Function Video

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  • 0:01 Muscle Function Disorders
  • 0:30 The Kinesias
  • 2:42 Myoclonus
  • 3:32 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
This lesson covers muscle function disorders, some that are transient and others that are not. These will include singultus, myoclonus, and '-kinesia' disorders (such as bradykinesia and dyskinesia), among others.

Muscle Function Disorders

Sometimes we are quick to react to a sudden event. Like, maybe you quickly catch a falling object. Other days, we seem to move slowly here and there because we are lethargic. Those are all temporary problems or events. But there are sometimes permanent muscle function disorders where there is an unusual quality or rate of movement for which terms, believe it or not, exist. Yep, we're going to learn about the terms related to muscle function, activity, and movement.

The Kinesias

Let's meet a family. It's the Kinesia family. The Kinesias are your typical family. There's a mom, dad, a boy, and a girl. Whether the Kinesia family knows it or not, their last name is derived from a suffix for movement: '-kinesia.'

The dad is a bit slow. Actually, he's really slow, but not up there in the head. No, he's just really slow in his movement. The abnormal slowness of a performed movement, as per diseases such as Parkinson's disease, is called bradykinesia, where 'brady-' means slow.

Mom has her own problems, though. They're similar to dad's, but not exactly the same. See, she has abnormally slow movements that are also smaller than desired as a result of abnormally decreased muscle function or activity, something called hypokinesia, where 'hypo-' means an abnormal decrease in something.

If the distinction between bradykinesia and hypokinesia isn't clear for you, let me give you an example. If dad, who has bradykinesia, writes out something, he does it abnormally slowly. If mom, who has hypokinesia, writes out something, she not only writes it out abnormally slowly, the written words are also smaller than she would like them to be, meaning her handwriting is tiny!

By the way, bradykinesia and hypokinesia shouldn't be confused with akinesia, even if they're all sometimes used synonymously. Akinesia refers to the absence of spontaneous movement or voluntary movement. As in, a person's arms don't swing as they walk. The prefix 'a-' means without.

But the little boy in the Kinesia family, quite stereotypically, doesn't have this problem as he's a bit hyperactive. He's got hyperkinesia, abnormally increased muscular activity or function, where 'hyper-' means an abnormal increase in something. And the little girl in the family has dyskinesia, the impairment or distortion of voluntary movement, as in a tic or spasm. The suffix of 'dys-' means bad.


Now that we've had fun meeting the Kinesia family, let's segue over to a few fun terms about our daily life that have to deal with muscle-related problems, even if they're not as significant as those found in the Kinesia family. Have you ever had a sudden, shock-like, and involuntary jerking and contraction of one or more muscles, called myoclonus? 'Myo-' stands for muscle, and '-clonus' comes from the Greek for turmoil.

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