Table of ContentsView AllTable of ContentsWhat Is the Difference Between Voluntary and Involuntary Muscles?Skeletal Muscle Diseases, Neuromuscular Disorders, and Other CausesFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
What Is the Difference Between Voluntary and Involuntary Muscles?
Skeletal Muscle Diseases, Neuromuscular Disorders, and Other Causes
Frequently Asked Questions
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Voluntary muscles are skeletal muscles that contract and relax under conscious control. These muscles attach to bones and regulate movement of the body.
Involuntary muscles, on the other hand, are not under conscious control. They contract and relax automatically and receive signals from the autonomic nervous system, which regulates your internal bodily functions.
Voluntary Muscles
Voluntary muscles are skeletal muscles that make up 40% of your body weight and consist of 50% to 75% of your total body’s proteins. Skeletal muscles can convert chemical energy into mechanical energy to cause voluntary muscle contraction and movement.
Skeletal muscle is composed of fascicles, bundled units of multiple muscle fibers or muscle cells. Each muscle fiber consists of a cross-banded structure that is further divided into myofibrils that contain thick (myosin) and thin (actin) myofilaments, which give muscle its stripe appearance. This structure gives skeletal muscle a characteristic striated structure.
Common examples of skeletal muscles include major muscle groups that control movement of the arms, legs, and body, such as the biceps, triceps, glutes, quadriceps, hamstrings, and abdominals.
Involuntary Muscles
Involuntary smooth muscles include thediaphragm, intestines, bladder, and walls of blood vessels.
The one exception of an involuntary muscle is the myocardium, or heart muscle. The myocardium is composed of a specialized type of muscle cell called cardiac muscle that is only found in the heart.
What Is Asthenia?
Weak Voluntary Muscles: Skeletal Muscle Diseases, Neuromuscular Disorders, and Other Causes
Neuromuscular disorders, also called skeletal muscle disorders, are conditions that affect the nerves that send electrical signals to voluntary skeletal muscles to control movement.
Nerves communicate with muscles through the release ofneurotransmittersat the neuromuscular junction, the space between a nerve cell and muscle fiber. Neuromuscular disorders can damage the nerve itself or the neuromuscular junction, where the signal is transmitted from a nerve to a muscle.
Symptoms of neuromuscular disorders include:
Common neuromuscular disorders include:
Muscle weakness can also result fromelectrolyte imbalances, such as altered levels of sodium, potassium, calcium, or magnesium.
What Are Muscular System Diseases?
Summary
Skeletal muscles that attach to bones such as the muscles of your arms, legs, neck, back, and trunk are voluntary muscles that you can consciously control. Weakness or inability to control voluntary skeletal muscles can signal a health issue like a neuromuscular disorder or electrolyte imbalance. Involuntary muscles include those involved in automatic internal processes needed for survival that control your blood vessels and organs like your heart, lungs, and digestive system.
A Word From Verywell
Skeletal muscles are muscles under voluntary control that cause parts of your body like your arms, legs, and body to move when contracted. If you experience skeletal muscle weakness, make sure to discuss your type and duration of symptoms with your doctor, as this might be a sign of a medical condition such as a neuromuscular disorder. Always seek immediate medical attention for any sudden, unexplained weakness in your muscles.
Frequently Asked QuestionsVoluntary muscles are skeletal muscles that attach to bones and can be consciously activated to control movement. Common voluntary skeletal muscles include the biceps, triceps, lats, abdominals, glutes, quadriceps, and hamstrings.Voluntary muscles often work in pairs to symmetrically control movement on both sides of the body and support good posture and joint alignment. More than one muscle group is also activated at once when performing movements, as most muscles work together to coordinate movement and have more than one function.
Voluntary muscles are skeletal muscles that attach to bones and can be consciously activated to control movement. Common voluntary skeletal muscles include the biceps, triceps, lats, abdominals, glutes, quadriceps, and hamstrings.
Voluntary muscles often work in pairs to symmetrically control movement on both sides of the body and support good posture and joint alignment. More than one muscle group is also activated at once when performing movements, as most muscles work together to coordinate movement and have more than one function.
3 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Trovato FM, Imbesi M, Conway N, Castrogiovanni P.Morphological and functional aspects of human skeletal muscle.J Funct Morphol Kinesiol. 2016;1(3):289-302. doi:10.3390/jfmk1030289Webb RC.Smooth muscle contraction and relaxation.Adv Physiol Educ. 2003;27(4):201-206. doi:10.1152/advan.00025.2003Cleveland Clinic.Mitochondrial diseases.
3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Trovato FM, Imbesi M, Conway N, Castrogiovanni P.Morphological and functional aspects of human skeletal muscle.J Funct Morphol Kinesiol. 2016;1(3):289-302. doi:10.3390/jfmk1030289Webb RC.Smooth muscle contraction and relaxation.Adv Physiol Educ. 2003;27(4):201-206. doi:10.1152/advan.00025.2003Cleveland Clinic.Mitochondrial diseases.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Trovato FM, Imbesi M, Conway N, Castrogiovanni P.Morphological and functional aspects of human skeletal muscle.J Funct Morphol Kinesiol. 2016;1(3):289-302. doi:10.3390/jfmk1030289Webb RC.Smooth muscle contraction and relaxation.Adv Physiol Educ. 2003;27(4):201-206. doi:10.1152/advan.00025.2003Cleveland Clinic.Mitochondrial diseases.
Trovato FM, Imbesi M, Conway N, Castrogiovanni P.Morphological and functional aspects of human skeletal muscle.J Funct Morphol Kinesiol. 2016;1(3):289-302. doi:10.3390/jfmk1030289
Webb RC.Smooth muscle contraction and relaxation.Adv Physiol Educ. 2003;27(4):201-206. doi:10.1152/advan.00025.2003
Cleveland Clinic.Mitochondrial diseases.
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