Magnesium - "The Missing Mineral"
The neuromuscular system is the combination of the nervous system and muscles, working together to permit movement. The brain controls the movements of skeletal (voluntary) muscles via specialized nerve cells (neurons).
Process to
move a body part. A message (an action potential) is sent to upper motor neurons, which have long tails (axons) that go into and
through the brain, and into
the spinal cord, where they connect
with lower motor neurons. At the
spinal cord, ~50-200 lower motor neurons in the spinal cord send their axons via
nerves in the arms and legs directly to the muscle they control.
Each lower motor neuron is subdivided into many tiny branches. The tip of each
branch is called a presynaptic terminal.
The connection between the tip of the nerve and the muscle is called the
neuromuscular junction.
The neurotransmitter ACETYLCHOLINE triggers skeletal muscle contraction. The electrical signal from the brain (action potential) travels down the nerves (neurons) and prompts the release of the chemical ACETYLCHOLINE from the presynaptic terminals. This chemical is picked up by special sensors (receptors) in the muscle tissue. If enough receptors are stimulated by ACETYLCHOLINE your muscles will contract.
For skeletal muscles, the force exerted by the muscle is controlled by varying the frequency at which action potentialsare sent to muscle fibers.
Magnesium depletion leads to increased neuronal excitability and enhanced neuromuscular transmission. The opposite effect occurs with magnesium excess. An example of acute CNS magnesium deficiency is found in cattle with "grass staggers"(tetany), leading to severe muscle seizure and even death. In humans, a chronic magnesium deficit is implicated in neurological and neuromuscular conditions, such as migraine, CFS, and many other sleep and psychiatric disorders.
A decrease in neuronal magnesium concentration is postulated to increase calcium binding to prejunctional ACETYLCHOLINE vesicles. Increasing release of ACETYLCHOLINE into the neuromuscular cleft and so increasing muscle contractions.
With a relative deficiency of magnesium to calcium, calcium remains trapped in the muscle cells. Over time, if the relative deficiency continues (as often occurs in aging), the muscles become more or less permanently contracted, leading to increasing muscle tension and spasms.
