Muscle

Muscle is a contractile form of tissue. It is one of the four major tissue types, the other three being epithelium, connective tissue and nervous tissue. Muscle contraction is used to move parts of the body, as well as to move substances within the body.

Nervous control

Efferent leg

Vertebrates move muscles in response to voluntary and autonomic signals from the brain. Deep muscles, superficial muscles, muscles of the face and internal muscles all correspond with dedicated regions in the brain.

Related Topics:
Voluntary - Autonomic - Brain

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In addition, muscles react to reflexive nerve stimuli that do not always send signals all the way to the brain, but most muscle activity is the result of complex interactions between various areas of the brain.

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Nerves that control skeletal muscles in mammals correspond with neuron groups along the primary motor cortex of the brain's cerebral cortex. Commands are routed though the basal ganglia and are modified by input from the cerebellum before being relayed through the pyramidal tract to the spinal cord and from there to the motor end plate at the muscles. Along the way, feedback loops such as that of the extrapyramidal system contribute signals to influence muscle tone and response.

Related Topics:
Mammals - Primary motor cortex - Cerebral cortex - Basal ganglia - Cerebellum - Pyramidal tract - Spinal cord - Motor end plate - Extrapyramidal system

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Deeper muscles such as those involved in posture often are controlled from nuclei in the brain stem and basal ganglia.

Related Topics:
Brain stem - Basal ganglia

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Afferent leg

Sometimes known as muscle memory, the sense of where our bodies are in space is called proprioception, the perception of body awareness. More easily demonstrated than explained, proprioception is the "unconscious" awareness of where the various regions of the body are located at any one time. This can be demonstrated by anyone closing their eyes and waving their hand around. Assuming proper proprioceptive function, at no time will the person lose awareness of where the hand actually is, even though it is not being detected by any of the other senses.

Related Topics:
Muscle memory - Sense - Proprioception

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Several areas in the brain coordinate movement and position with the feedback information gained from proprioception. The cerebellum and nucleus ruber in particular continuously sample position against movement and make minor corrections to assure a smooth projection.

Related Topics:
Cerebellum - Nucleus ruber

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