Bodybuilder showing highly developed muscle tone.

Muscle tone (aka residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles. It helps maintain posture and declines during REM sleep. Note that muscular tone is not defined as muscular shaping or the aspect of general Human physical appearance. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... A top-down view of skeletal muscle Muscle (from Latin musculus little mouse [1]) is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... While not moving, a human can be in one of the following main positions. ... Rapid eye movement (REM) is the stage of sleep during which the most vivid (though not all) dreams occur. ... Variation in the physical appearance of humans is believed by anthropologists to be an important factor in the development of personality and social relations in particular physical attractiveness. ...

Purpose

Unconscious nerve impulses maintain the muscles in a partially contracted state. If a sudden pull or stretch occurs, the body responds by automatically increasing the muscle's tension, a reflex which helps guard against danger as well as helping to maintain balance. A. Schematic of an electrophysiological recording of an action potential showing the various phases which occur as the wave passes a point on a cell membrane. ... Balance is the result of a number of body systems working together. ...

The presence of near-continuous innervation makes it clear that tonus describes a "default" or "steady state" condition. There is, for the most part, no actual "rest state" insofar as activation is concerned.

In terms of skeletal muscle, both the extensor muscle and flexor muscle use the term tonus to refer to the "at rest" or normal enervation that maintains current positions of bones. An extensor muscle is any skeletal muscle that opens a joint increasing the angle between components of a limb, such as straightening the knee or elbow and bending the wrist or spine. ... A flexor muscle is a skeletal muscle whose contraction bends a joint, decreasing the angle between components of a limb, such as bending the knee or elbow. ...

Cardiac muscle and smooth muscle, although not directly connected to the skeleton also have tonus in the sense that although their contractions are not matched with those of antagonist muscles, their non-contractive state is characterized by (sometimes random) enervation. Cardiac muscle is a type of involuntary striated muscle found within the heart. ... Cultured Smooth muscle of the aorta. ...

Pathological tonus

Physical disorders can result in abnormally low (hypotonia) or high (hypertonia) muscle tone. Another form of hypertonia is Paratonia, which is associated with dementia. Hypotonia is a condition of abnormally low muscle tone (the amount of tension or resistance to movement in a muscle), often involving reduced muscle strength. ... An increase in stiffness, tension, and spasticity of a muscle. ... Paratonia is classified as a form of hypertonia with an involuntary variable resistance (i. ...

Tonus in surgery

In ophthalmology, tonus may be a central consideration in eye surgery, as in the manipulation of extraocular muscles to repair strabismus. Tonicity aberrations are associated with many diseases of the eye (e.g. Adie syndrome). This article is about the branch of medicine. ... Eye surgery in the middle ages. ... The extraocular muscles are the six muscles that control the movements of the eye. ... Strabismus (from Greek: στραβισμός strabismos, from στραβίζειν strabizein to squint, from στραβός strabos squinting, squint-eyed[1]) is a condition in which the eyes are not properly aligned with each other. ... Adie syndrome, also Adies syndrome, is caused by damage to the postganglionic fibers of the parasympathetic innervation of the eye and characterized by a tonically dilated pupil. ...

Tonus training

Some^[Cite] present the idea that constant daily resistance training, or training at high intensities, will increase one's muscle tone, as the neurological system becomes more tense after constant exertion to stay in a state of greater readiness for the tension.

References

External links

• Tone vs. strength - Diane E Gagnon, M.Ed., PT (Physiotherapist)
• BBC series on muscles