Muscular system explained

What is the muscular system?

The muscular system comprises three distinct types of muscle: smooth, cardiac, and skeletal. Cardiac muscles make up the heart, whereas smooth and skeletal muscles are found throughout the body. Smooth muscles line blood vessels and most organs, and skeletal muscles are responsible for moving the body or holding it stationary. All muscles are made of muscle cells or fibers, which give them the ability to contract.

What does the muscular system do?

The muscular system is responsible for movement by and throughout the body. Smooth muscle contractions push food and blood through the digestive tract and blood vessels, respectively. Skeletal muscles are responsible for voluntary movement or lack thereof by the body. Cardiac muscle controls the beating of the heart, which is the pump that powers the circulatory system responsible for distributing energy and nutrients to cells across the body.

How skeletal and smooth muscles differ

Skeletal and smooth muscles are two of the three muscle types found throughout the body. The former is attached to bones via tendons, enables limb movement, and is consciously controlled. The latter is found lining blood vessels and hollow organs (e.g., the intestines, stomach, and esophagus) and is managed by the autonomic nervous system, which means it's outside conscious control.

Human anatomy 101: the body's systems

Human life is made possible by the body's ten major systems, which maintain homeostasis by responding to incoming sensory and biochemical input. Each system must work independently and collaboratively for the body to maintain health and respond appropriately to its internal and external environments. The bones of the skeletal system, for example, give the body its shape and protect organs while also facilitating movement with the muscular system.

One of the leading theories behind muscle movement

According to the Sliding Filament Theory, skeletal muscle contraction is made possible by sarcomeres, which are made of bundles of myosin and actin proteins inside muscle cells. Myosin pulls itself along actin to contract a muscle, shortening the muscle and its cells and enabling physical movement. It then releases its grasp on actin so it can start the process over again if so commanded.

What is the peripheral nervous system?

This nervous system extends throughout the body, where it acts as the informational bridge between the central nervous system, housed in the brain and spinal cord, and the body's muscles and organs. The peripheral nervous system is further divided into the autonomic, enteric, and somatic nervous systems, each of which oversees certain muscle types and processes. This article overviews the anatomy and functions of the peripheral nervous system.

How humans breathe without thinking about it

We breathe without thinking about it thanks to the body’s respiratory system and autonomic nervous system, which controls vital functions. Breathing transports oxygen to the body’s cells to keep them working and clears the body of carbon...

Physiological muscle memory allows us to quickly regain lost musculature

The term "muscle memory" is most often associated with the neurological kind, which involves the development of strong and efficient neural pathways in the brain and spine. Physiological muscle memory also slows the loss of muscle mass, with both types affected by genetics and diet.

How muscles get their names

There are more than 600 muscles that crisscross the human body, and each has a name that's more than a simple label. Muscle names also typically communicate the muscle's size, behavior, length, location, appearance, direction, and attachments to bone. These names usually have Greek or Latin roots, such as in the case of the deltoid muscles, which are named in reference to the Greek letter delta (𐤃).

Myokines are molecules that facilitate some of the benefits of exercise

When muscles contract, they release ‘hope molecules’ (myokines) such as IL-6 and irisin. These proteins then travel through the bloodstream to reduce inflammation, improve insulin sensitivity, and even support brain repair. This piece illustrates how movement triggers a systemic healing cascade throughout the human body.

What does a beating human heart look like?

Tucked behind your rib cage and between your lungs sits your heart. This knot of cardiac muscle will (typically) beat billions of times throughout your lifetime, sending oxygenated and nutrient-rich blood throughout the body, powering countless biological processes that have enabled you to read this very paragraph. This two-minute video provides a glimpse of the mechanics happening inside your chest via an animated anatomical model.

How ALS (Lou Gehrig’s Disease) might work, and what scientists are learning about it

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that affects the nerve cells (neurons) controlling muscle movement. As the motor neurons degenerate, they stop sending signals to the muscles, causing progressive muscle weakness and, eventually, death. This three-minute animation focuses on the mechanisms within the motor neurons that cause them to degenerate. By understanding these mechanisms, researchers hope to one day find a cure for ALS.

Snakes move around by coordinating hundreds of muscles

These muscles connect to their vertebrae, and allow the creature to move in various unique ways. Snakes can slither, move in a straight line, swim, jump and even "fly."

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How autoimmune diseases, which attack your own tissues and cells, work in the body

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The anatomy of 'Mashle,' as described by a doctor

"Mashle: Magic and Muscles" is a manga and anime in which a seemingly magicless man performs outsized feats he blames on "muscle magic." In this 15-minute video, a doctor breaks down the anatomy and biomechanics of some of the feats performed by Mash, the series' main character who's spotted flying a broom via leg pumping and reading magical texts while sitting in an invisible chair (i.e., single-leg squat).

Some animals may speak because of duplicated connections in the brain

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The anatomy of our hair follicles explains goose bumps

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Adults need two days of muscle strengthening activity weekly—yet most of us aren't doing that

That recommendation—muscle-strengthening activities on two or more days a week working all major muscle groups—is in addition to 150 minutes weekly of moderate-intensity physical activity. Those resistance and aerobic training numbers from the US government are echoed by other medical groups. But nearly 80% of adults aren't checking the box on those goals. This failure is linked to about $117B in annual health costs and some 10% of premature mortality.

Why yoga teachers are dissecting cadavers

Thousands of fitness professionals are choosing to attend cadaver workshops to improve their understanding of anatomy and their teaching abilities. Though 3D virtual models give students a fresh way to explore the human body, medical students say experiencing the intricacies in person is far more instructive. As fitness professionals increase their understanding of the muscular and skeletal systems, their movement cues and instructions evolve in tandem.

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Gladiators fought in specialized armatures designed only for the arena

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Explaining how water's movement between different salt concentrations can generate electricity

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A living will is a legal document spelling out your medical wishes for emergency care

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Tattoos, explained

Tattoos last because immune cells trap ink beneath the skin—but there's more to the story. This overview looks at how ancient cultures used tattoos for status, spirituality and punishment; how technology like the electric tattoo machine transformed the art form, and where innovations like smart tattoos could take it next.

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