The expressions listed in this category could also be described as:
- actions at joints
- actions of muscles, or
- muscle actions
For a single list of all the movements of the body included in this section see types of movements at joints.
Short definition of Extension (in the context of a term to describe movement of the body):
Extension is movement increasing the angle between articulating bones.
Another way to express this is 'increasing the inner angle of the joint'.
The opposite movement to that of extension is flexion.
It is useful to know words related to extension, including:
- extensor - a muscle that can act to cause an extension movement at a joint is called an extensor, e.g. the extensor carpi ulnaris muscle of the lower-arm extends the wrist (joint).
- to extend (verb) - e.g. as in the sentence: "It is necessary to extend the arm when participating in some sporting activities."
Examples of Extension:
- Extension of the elbow:
- Only try this exercise if you have no problems with the arm, wrist and hand -
In preparation: Bend one arm at the elbow, lifting the wrist of that arm towards the corresponding shoulder and rest the fingers of that hand on the shoulder.
Extension movement: Extend the elbow joint by straightening the arm so that the fingers that had been resting on the shoulder are at arm's length away from the shoulder. While performing this movement you can watch the angle at the elbow joint formed by the humerus (bone of the upper-arm) and the radius and ulna (bones of the lower arm) increase by approximately 145 degrees.
- The following video clip demonstrates hip extension exercises.
See also list of definitions of muscle terminology (words used to convey information about specific muscles) - useful for studying human anatomy and physiology, sports sciences e.g. physical education (PE), physiotherapy, and other health sciences.
About this section:
- actions at joints,
- actions of muscles or
- muscle actions.
For a single list summarizing all the movements of the body included in this section see
types of movements at joints.
See also definitions of muscle terminology (words used to convey information about specific muscles) - useful for studying human anatomy and physiology, sports sciences e.g. physical education (PE), physiotherapy, and other health sciences.
- Anterior Muscles
- Posterior Muscles
- Facial Muscles
- Muscle Terminology (Definitions)
- 1. Structure of Muscle
- 2. Structure of Muscle Cells
- 3. Muscle Filaments
- 4. Sliding Filament Theory
- 5. Neuromuscular Junction
- 6. Actions at Neuromuscular Junction
- Types of Muscle Contractions
- Muscular Disorders
- Effects of exercise on muscles