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Smooth muscle is involuntary and found in parts of the body where it conveys action without conscious intent. The majority of this type of muscle tissue is found in the digestive and urinary systems where it acts by propelling forward food, chyme, and feces in the former and urine in the latter.
Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. Most smooth muscle is of the single-unit type, and is found in the walls of most internal organs (viscera); and lines blood vessels (except large elastic arteries), the urinary tract , and the digestive tract .
The nerve(s) which tell the muscle to act (innervates the muscle). The term "nerve" is included for clarity. Action The movement performed by the muscle from the standard anatomical position. In other positions, other actions may be performed. Antagonist The muscle which can 'cancel' or to some degree reverse the action of the muscle.
Motor control includes conscious voluntary movements, subconscious muscle memory and involuntary reflexes, [1] as well as instinctual taxes. To control movement, the nervous system must integrate multimodal sensory information (both from the external world as well as proprioception ) and elicit the necessary signals to recruit muscles to carry ...
Cardiac muscle tissue is found only in the walls of the heart as myocardium, and it is an involuntary muscle controlled by the autonomic nervous system. Cardiac muscle tissue is striated like skeletal muscle, containing sarcomeres in highly regular arrangements of bundles.
For example, Antagonistic muscle cocontraction can be either voluntary or involuntary. Additionally, because much of the legs' movements are controlled by the spinal cord and because of the larger neural delay associated with sending signals to the leg muscles, leg stiffness is more involuntarily controlled than arm stiffness.
A common example of reciprocal innervation, is the effect of the nociceptive (or nocifensive) reflex, or defensive response to pain, otherwise commonly known as the withdrawal reflex; a type of involuntary action of the body to remove the body part from the vicinity of an offending object by contracting the appropriate muscles (usually flexor ...
In 1745, Whytt published An Equiry Into the Cause Which Promote the Circulation of Fluids in the Small Vessels of Animals where he states that the soul, also referred to as the sentient principle, and the body hold equal influence over movement and therefore may govern both voluntary and involuntary action. [2] Voluntary action is movement ...