In physiology, medicine, and anatomy, muscle tone (aka residual muscle tension or tonus) is the continuous and passive partial contraction of the muscles. Physiology (from Greek grc φύσις physis, "nature origin" and grc -λογία -logia) is the study of the mechanical physical Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration It helps maintain posture, and it declines during REM sleep. A Neutral Spine or "good posture" refers to the "three natural curves are present in a healthy spine It is not to be confused with the concept of toning in physical exercise. Toning exercises are Physical exercises that aim to develop Musculature that is hard as opposed to flaccid

Purpose

Unconscious nerve impulses maintain the muscles in a partially contracted state. In Neurophysiology, the action potential is a self-regenerating Wave of Electrochemical activity that allows Nerve cells to carry a signal 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. In Physiology, Medicine, and Anatomy, muscle tone (aka residual muscle tension or tonus) is the continuous and passive partial A balance disorder is a disturbance that causes an individual to feel unsteady giddy woozy or have a sensation of movement spinning or floating

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 and flexor muscles, under normal enervation maintain a constant tone while "at rest" that maintains a normal posture. An extensor muscle is any Muscle that opens a joint increasing the angle between components of a limb such as straightening the Knee or elbow and bending 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 A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons.

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. The cardiac muscle is a type of involuntary striated Muscle found in the walls of the Heart. Smooth muscle is a type of non- Striated muscle, found within the Tunica media layer of large and small Arteries and Veins, the bladder

Pathological tonus

Physical disorders can result in abnormally low (hypotonia) or high (hypertonia) muscle tone. 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 Hypertonia is an Upper motor neuron dysfunction marked by an abnormal increase in tightness of Muscle tone and a reduced ability of a muscle to stretch Another form of hypertonia is Paratonia, which is associated with dementia. Paratonia, also known as gegenhalten, is classified as a form of Hypertonia with an involuntary variable resistance (i Dementia (from Latin de- "apart away" + Mens ( genitive mentis) "mind" is the progressive decline

Tonus in surgery

In ophthalmology, tonus may be a central consideration in eye surgery, as in the manipulation of extraocular muscles to repair strabismus. Ophthalmology is the branch of Medicine which deals with the diseases and surgery of the visual pathways including the Eye, Brain Eye surgery, also known as orogolomistician surgery or ocular surgery, is Surgery performed on the Eye or its Adnexa, typically by The extraocular muscles are the six Muscles that control the movements of the (human eye. Strabismus (from Greek: στραβισμός strabismos, from στραβίζειν strabizein "to squint" from στραβός strabos Tonicity aberrations are associated with many diseases of the eye (e. g. Adie syndrome). Adie syndrome, sometimes known as Holmes-Adie's syndrome or Adie's Tonic Pupil, is a Neurological disorder which affects the Pupil of the eye

References

External links

• BBC series on muscles