what causes your body muscles to be weak

For a person to intentionally movement a muscle (called a voluntary musculus contraction), the brain must generate a signal that travels a pathway from

• The encephalon

• Through nerve cells in the encephalon stalk and spinal string

• Through fretfulness from the spinal cord to the muscles (called peripheral fretfulness)

• Beyond the connection between nerve and muscle (called a neuromuscular junction)

Using the Brain to Movement a Muscle

Moving a muscle usually involves communication between the muscle and the brain through fretfulness. The impetus to move a muscle may originate in the encephalon, as when a person consciously decides to move a muscle—for example, to option up a book. Or the impetus to movement a muscle may originate with the senses. For example, special nerve endings in the skin (sensory receptors) enable people to sense pain or a change in temperature. This sensory information is sent to the brain, and the brain may send a bulletin to the musculus about how to respond. This type of exchange involves two complex nerve pathways: The sensory nervus pathway to the brain The motor nervus pathway to the muscle
	If sensory receptors in the skin detect pain or a change in temperature, they transmit an impulse (signal), which ultimately reaches the brain. The impulse travels forth a sensory nerve to the spinal string. The impulse crosses a synapse (the junction between ii nerve cells) between the sensory nerve and a nerve cell in the spinal cord. The impulse crosses from the nervus jail cell in the spinal cord to the contrary side of the spinal cord. The impulse is sent up the spinal cord and through the brain stem to the thalamus, which is a processing center for sensory data, located deep in the brain. The impulse crosses a synapse in the thalamus to nerve fibers that deport the impulse to the sensory cortex of the cerebrum (the area that receives and interprets information from sensory receptors). The sensory cortex perceives the impulse. A person may then decide to initiate motility, which triggers the motor cortex (the area that plans, controls, and executes voluntary movements) to generate an impulse. The nerve carrying the impulse crosses to the opposite side at the base of the brain. The impulse is sent downwards the spinal string. The impulse crosses a synapse between the nervus fibers in the spinal string and a motor nerve, which is located in the spinal cord. The impulse travels out of the spinal cord along the length of the motor nerve. At the neuromuscular junction (where nerves connect to muscles), the impulse crosses from the motor nerve to receptors on the motor terminate plate of the muscle, where the impulse stimulates the muscle to move.
If the awareness occurs of a sudden and is astringent (as when stepping on a precipitous rock or picking upwardly a loving cup of very hot coffee), the impulse may travel to the spinal cord and directly back to the motor nerve, bypassing the encephalon. The result is a quick response of a muscle—past immediately withdrawing from whatsoever is causing the pain. This response is called a spinal reflex.

Too, the corporeality of musculus tissue must be normal, and the tissue must be able to contract in response to the point from the nerves. Therefore, true weakness results only when one or more role of this pathway―brain, spinal cord, nerves, muscles, or the connections betwixt them―is damaged or diseased.

Weakness may develop suddenly or gradually. Weakness may impact all of the muscles in the body (chosen generalized weakness) or simply one part of the trunk. For example, depending on where the spinal cord is damaged, spinal cord disorders may cause weakness just of the legs.

Symptoms depend on which muscles are afflicted. For instance, when weakness affects muscles of the chest, people may have difficulty breathing. When weakness affects muscles that control the eyes, people may have double vision.

Complete muscle weakness causes paralysis. People may have other symptoms depending on what is causing the weakness. Weakness is often accompanied by abnormalities in awareness, such as tingling, a pins-and-needles sensation, and numbness.

Because malfunction in the same part of the signal pathway causes similar symptoms regardless of cause, the many causes of muscle weakness are usually grouped by the location of the cause (encounter table Some Causes and Features of Muscle Weakness Some Causes and Features of Muscle Weakness ). That is, causes are grouped every bit those that affect the encephalon, spinal string, peripheral nerves, muscles, or connections betwixt nerves and muscles. However, some disorders bear upon more 1 location.

Causes differ depending on whether weakness is generalized or affects only specific muscles.

For generalized weakness, the most common causes are

• A decrease in full general physical fitness (called deconditioning), which may result from illness and/or a decrease in physical reserves (frailty), such as musculus mass, bone density, and the heart'southward and lungs' ability to function, especially in older people

• Loss of muscle tissue (wasting, or atrophy) due to long periods of inactivity or bed rest, as occurs in an intensive care unit (ICU)

• Damage to nerves due to a severe affliction or injury, such as astringent or extensive burns

• Certain conditions that damage muscle, such equally a low level of potassium (hypokalemia Hypokalemia (Depression Level of Potassium in the Blood) In hypokalemia, the level of potassium in blood is likewise depression. A low potassium level has many causes but normally results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics. A... read more than ), consumption of too much alcohol Booze Alcohol (ethanol) is a depressant. Consuming large amounts rapidly or regularly tin cause health problems, including organ damage, coma, and death. Genetics and personal characteristics may... read more , or employ of corticosteroids

• Drugs used to paralyze muscles—for example, to go on people from moving during surgery or while on a ventilator

For weakness in specific muscles, the most common causes are

Many other conditions sometimes crusade weakness (run across table Some Causes and Features of Musculus Weakness Some Causes and Features of Musculus Weakness ). For instance, electrolyte abnormalities (such as a depression level of magnesium Hypomagnesemia (Low Level of Magnesium in the Claret) In hypomagnesemia, the level of magnesium in claret is too low. (Run across also Overview of Electrolytes and Overview of Magnesium's Function in the Body.) Magnesium is one of the trunk's electrolytes... read more or calcium Hypocalcemia (Low Level of Calcium in the Claret) In hypocalcemia, the calcium level in claret is too low. A low calcium level may consequence from a problem with the parathyroid glands, every bit well as from nutrition, kidney disorders, or certain drugs. As... read more ) can cause weakness that sometimes comes and goes, as well as muscle cramping Musculus Cramps A balk is a sudden, brief, unintended (involuntary), and usually painful contraction of a muscle or group of muscles. Musculus cramps can exist a symptom of nervous organization malfunction. The most... read more and twitches.

In people with a seizure disorder, 1 side of the body may go weak after a seizure stops (called Todd paralysis). The weakness usually subsides over several hours.

Many people report weakness when their trouble is actually fatigue Fatigue Fatigue is when a person feels a strong need to rest and has so petty energy that starting and sustaining activity is difficult. Fatigue is normal subsequently physical exertion, prolonged stress... read more . Common causes of fatigue include a severe disease, cancer, a chronic infection (such as HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys sure white blood cells and can cause acquired immunodeficiency syndrome (AIDS). HIV is transmitted... read more , hepatitis Overview of Hepatitis Hepatitis is inflammation of the liver. (See also Overview of Acute Viral Hepatitis and Overview of Chronic Hepatitis.) Hepatitis is mutual throughout the globe. Hepatitis tin can be Astute (short-lived) read more than , or mononucleosis Infectious Mononucleosis Epstein-Barr virus causes a number of diseases, including infectious mononucleosis. The virus is spread through kissing. Symptoms vary, merely the most common are farthermost fatigue, fever, sore pharynx... read more than ), middle failure Heart Failure (HF) Eye failure is a disorder in which the heart is unable to go along upwards with the demands of the body, leading to reduced blood menstruum, redundancy (congestion) of blood in the veins and lungs, and/or... read more than , kidney failure Overview of Kidney Failure This affiliate includes a new section on COVID-19 and acute kidney injury (AKI). Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the claret. Kidney... read more , liver failure Liver Failure Liver failure is severe deterioration in liver function. Liver failure is caused past a disorder or substance that damages the liver. Almost people have jaundice (yellow skin and eyes), feel tired... read more than , anemia Overview of Anemia Anemia is a status in which the number of carmine claret cells is low. Scarlet blood cells contain hemoglobin, a protein that enables them to carry oxygen from the lungs and deliver it to all parts... read more , chronic fatigue syndrome Chronic Fatigue Syndrome Chronic fatigue syndrome, also called myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), refers to long-continuing severe and disabling fatigue without a proven physical or psychologic... read more than , fibromyalgia Fibromyalgia Fibromyalgia is characterized past poor sleep, fatigue, mental cloudiness, and widespread aching and stiffness in soft tissues, including muscles, tendons, and ligaments. Poor slumber, stress, strains... read more than , and mood disorders (such as low Low A short discussion of prolonged grief disorder. Depression is a feeling of sadness and/or a decreased interest or pleasure in activities that becomes a disorder when it is intense enough to... read more than ).

Multiple sclerosis can crusade fatigue that increases when people are exposed to oestrus and humidity.

Outset, doctors try to determine whether people are weak or simply tired. If people are weak, doctors then determine whether the weakness is severe enough or worsening chop-chop plenty to exist life threatening. Doctors likewise try to identify the crusade.

In people with weakness, the post-obit symptoms are cause for concern:

• Weakness that becomes astringent over a few days or less

• Difficulty animate

• Difficulty raising the caput while lying down

• Difficulty chewing, talking, or swallowing

• Loss of the ability to walk

People who accept any warning sign should go to an emergency section immediately. Immediate medical attention is crucial because weakness accompanied by a alert sign can worsen apace and cause permanent disability or be fatal.

People without warning signs should call their doctor. The medico can determine how speedily they need to be seen based on their symptoms and other disorders they accept.

If the weakness worsens gradually (over months to years), people should hash out the problem with their doc at their side by side visit.

Doctors ask people to describe in detail what they are experiencing every bit weakness. Doctors ask

• When the weakness began

• Whether it began suddenly or gradually

• Whether information technology is constant or is worsening

• Which muscles are affected

• Whether and how the weakness affects the ability to do sure activities, such every bit breathing, brushing their teeth or hair, speaking, swallowing, standing upwardly from a seated position, climbing stairs, and walking

• Whether they accept other symptoms that indicate malfunction of the nervous organization, such every bit speech or vision problems, loss of awareness or memory, or seizures

• Whether any activeness or condition (such as rut or repetitive use of a muscle) makes the weakness worse

What seems to be sudden weakness is sometimes gradual weakness, but people practice non notice it until they can no longer do something, such as walking or tying their shoes.

Based on the description of weakness, doctors can often identify the well-nigh likely causes, as for the following:

• A musculus disorder: Weakness start in the hips and thighs or the shoulders (that is, people accept difficulty standing upwards or lifting their arms overhead) and no outcome on sensation

• A peripheral nervus disorder: Weakness beginning in the hands and anxiety (that is, people have difficulty lifting a cup, writing, or stepping over a curb) and loss of awareness

Doctors likewise inquire almost other symptoms, which may suggest i or more possible causes. For example, if people with back pain and a history of cancer report weakness in a leg, the cause may exist cancer that has spread and put pressure on the spinal string.

Doctors ask well-nigh atmospheric condition that increase risk of disorders that cause weakness. For example, They ask people whether they have high blood pressure and atherosclerosis (which increase the risk of stroke) or have traveled to surface area whether Lyme affliction is common.

Doctors ask about past and current use of drugs, including booze and recreational drugs.

Whether family members have had similar symptoms can help doctors determine whether the cause is hereditary.

Doctors find how the person walks. How people walk may suggest the disorder that is causing symptoms or its location. For case, if people elevate a leg, exercise non swing one arm equally much as the other when walking, or both, their symptoms may exist acquired by a stroke. Doctors as well cheque for other signs that the nervous organisation is malfunctioning, such equally loss of coordination or sensation.

• The brain or spinal cord: If reflexes are very easy to trigger and are very strong

• The nerves: If reflexes are difficult to trigger and are slow or absent

A general physical exam is done to look for other symptoms that may propose a cause, such as shortness of breath (possibly caused by a middle or lung disorder).

By and large, if the history and concrete examination do not detect specific abnormalities that suggest a encephalon, spinal cord, nerve, or muscle disorder, the cause is likely to be fatigue.

Other testing is washed based on where doctors remember the trouble is:

• A encephalon disorder: Magnetic resonance imaging (MRI) or, if MRI is not possible, computed tomography (CT)

• A spinal cord disorder: MRI or, if MRI is not possible, CT myelography and sometimes a spinal tap (lumbar puncture)

• A peripheral nerve disorder (including polyneuropathies) or a neuromuscular junction disorder: Electromyography and usually nerve conduction studies

• A muscle disorder (myopathy): Electromyography, unremarkably nerve conduction studies, and possibly MRI, measurement of muscle enzymes, muscle biopsy, and/or genetic testing.

Occasionally, MRI is not available or cannot exist washed—for example, in people who take a pacemaker, another implanted metal device, or other metal (such as shrapnel) in their torso. In such cases, another examination is substituted.

If people accept no symptoms too weakness and no abnormalities are detected during the exam, test results are usually normal. However, doctors sometimes practice certain claret tests, such as

• A complete blood cell count (CBC)

• Measurement of levels of electrolytes (such as potassium, calcium, and magnesium), sugar (glucose), and thyroid-stimulating hormone

• Erythrocyte sedimentation rate (ESR), which can detect inflammation

Blood tests are sometimes done to evaluate kidney and liver office and to check for the hepatitis virus.

Physical and occupational therapy can help people adapt to permanent weakness and compensate for loss of function. Concrete therapy can help people maintain and sometimes regain strength.

Every bit people historic period, the amount of musculus tissue and muscle strength tend to subtract. These changes occur partly because older people may go less active but also considering the production of the hormones that stimulate musculus evolution decreases. Thus, for older people, bed remainder during an affliction can have a devastating effect. Compared with younger people, older people start out with less muscle tissue and force at the get-go of the illness and lose musculus tissue more quickly during the illness.

Drugs are some other common cause of weakness in older people because older people take more drugs and are more susceptible to side effects of drugs (including muscle damage and bug with nerves).

When evaluating older people who report weakness, doctors also focus on weather condition that practise not crusade weakness only interfere with balance, coordination, vision, or mobility or that make movement painful (such as arthritis). Older people may mistakenly depict the effects of such weather as weakness.

Regardless of what is causing weakness, concrete therapy tin usually assist older people function improve.

• Many people mistakenly say they experience weak when they really hateful they are tired or their movement is limited because of pain and/or stiffness.

• Truthful muscle weakness results only when one part of the pathway necessary for voluntary musculus movement (from brain to muscles) malfunctions.

• Often, doctors can determine whether the problem is true muscle weakness and tin can identify the cause based on the pattern of symptoms and results of the concrete exam.

• Concrete therapy is usually helpful in maintaining strength no matter what the cause of weakness is.

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Source: https://www.msdmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/symptoms-of-brain-spinal-cord-and-nerve-disorders/weakness

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