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The human body is made up of more than 600 muscles, which are pieces of soft tissue that help us do everything from breathing to running marathons. There are three types of muscle tissue in the body: skeletal, smooth, and cardiac. Skeletal muscles are the most common type, making up between 30% and 40% of our total body mass, and they are attached to bones by tendons. They help us move our bones and perform daily activities. Smooth muscles are found in the walls of blood vessels and structures like the urinary bladder, intestines, and stomach, and they help move food through the digestive tract. Cardiac muscles make up the mass of the heart and are responsible for its rhythmic contractions, pumping blood throughout the body.
| Characteristics | Values |
|---|---|
| Number of muscles in the body | 600+ |
| Muscle composition | Thousands of small fibres woven together |
| Types of muscle tissue | Visceral, cardiac, skeletal |
| Skeletal muscle composition | Tissue, blood vessels, tendons, nerves |
| Skeletal muscle mass | 30-40% of total body mass |
| Skeletal muscle types | Type I (slow-twitch), Type II (fast-twitch) |
| Cardiac muscle location | Middle layers of the heart |
| Smooth muscle location | Walls of organs and structures like the oesophagus, stomach, intestines, bronchi, etc. |
| Smooth muscle function | Moving waste through intestines, helping lungs expand, etc. |
| Skeletal muscle function | Chewing, swallowing, expanding and contracting chest cavity, etc. |
| Muscle injuries | Strains, pulls, tears |
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What You'll Learn
- Skeletal muscles are attached to bones and make up 30-40% of body mass
- Cardiac muscle makes up the heart and is involuntary
- Smooth muscle is involuntary and found in the walls of blood vessels
- Visceral muscle is the weakest type and found in organs like the stomach
- Facial muscles don't attach to bone but under the skin, allowing for small movements
Skeletal muscles are attached to bones and make up 30-40% of body mass
Skeletal muscles are attached to bones through tendons, which are tough connective tissues. They are the most common type of muscle in the human body, accounting for 30-40% of total body mass. They are also the only voluntary muscles, meaning that their movement is controlled consciously. When you decide to move a part of your body, the skeletal muscles in that area contract, allowing you to perform a wide range of movements and functions.
Skeletal muscles are found throughout the body, including in the tongue, diaphragm, eye socket, and upper oesophagus. They are responsible for various functions, such as producing movement, maintaining body posture and position, and stabilizing joints. They also play a role in respiratory mechanics and maintaining balance. Additionally, skeletal muscles help maintain body temperature and store nutrients.
Skeletal muscles are composed of thousands of small fibres that contract and press together to enable movement. These fibres are surrounded by different types of sheaths or coverings, including the epimysium, perimysium, and endomysium. The strength of a skeletal muscle is determined by its cross-sectional area, with a larger area resulting in greater force exertion.
The health of skeletal muscles is crucial for overall well-being. Muscle strains, or pulled muscles, are a common injury that occurs when the muscle fibres are stretched beyond their limit and tear. Maintaining muscle strength through exercise is important for bone health, balance, and flexibility. Skeletal muscle mass varies from person to person, with males generally having more skeletal muscle mass than females.
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Cardiac muscle makes up the heart and is involuntary
The human body has about 700 named muscles, making up roughly half of a person's body weight. There are three types of muscle tissue in the body: skeletal, smooth, and cardiac.
Cardiac muscle, also called the myocardium, is one of the three major categories of muscles found within the human body. It makes up the thick middle layer of the heart. The heart is made up of three layers: the pericardium, myocardium, and endocardium. The endocardium is not cardiac muscle and forms the inner lining of the heart chambers and valves. The pericardium is a fibrous sac surrounding the heart, consisting of the epicardium, pericardial space, parietal pericardium, and fibrous pericardium.
The primary function of cardiac muscle is to pump blood into circulation by generating sufficient force. Cardiac muscle cells can increase contractility through beta-1 adrenergic receptors on the surface with a Gs G-protein. When stimulated by either the sympathetic nervous system or beta-1 agonist drugs, the Gs activate the enzyme adenylyl cyclase, which converts ATP to cAMP. The contractile functions of the heart require ATP, which can be obtained through various substrates, including fatty acids, carbohydrates, proteins, and ketones.
Cardiac muscle is under involuntary control. The heart beats on its own without any conscious input from the brain. Cardiac muscle stimulates itself to contract. The natural pacemaker of the heart is made of cardiac muscle tissue that stimulates other cardiac muscle cells to contract. Because of its self-stimulation, cardiac muscle is considered to be autorhythmic or intrinsically controlled.
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Smooth muscle is involuntary and found in the walls of blood vessels
The human body has three types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are voluntary muscles, meaning an individual has control over how and when they move and work. Cardiac and smooth muscles, on the other hand, are involuntary muscles that the autonomic nervous system controls. Smooth muscles are involuntary muscles that line the inside of some organs. They are found throughout the body and serve a variety of functions.
Smooth muscle is found in the stomach and intestines, where it helps with digestion and nutrient collection. It is also present in the urinary system, where it helps rid the body of toxins and maintains electrolyte balance. Smooth muscle is also found in the walls of arteries and veins, where it plays a vital role in regulating blood pressure and tissue oxygenation. Without these vital functions, the body would not be able to maintain even its most basic functions.
Smooth muscle is a type of non-striated involuntary muscle, which generally forms the supporting tissue of blood vessels and hollow internal organs, such as the stomach, intestine, and bladder. Smooth muscle is found within the tunica media, the middle layer, of the artery wall. There is a larger amount of smooth muscle in the walls of arteries than in veins, hence their greater wall thickness. Smooth muscle is derived from both mesoderm and neural crest cells. This is because smooth muscle contributes to many different tissues throughout the body.
Vascular smooth muscle cells, also referred to as mural cells, are essential for vascular development and stability. Mural cells wrap around larger vessels and exert significant influence on the regulation of blood flow, endothelial network growth, and vessel stability. Smooth muscle is present in almost every artery in the body, supplying blood to smooth muscle in the form of endothelial smooth muscle located directly in the artery or smooth muscle within an organ system. Smooth muscle helps regulate blood flow by controlling the diameter of the vessel.
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Visceral muscle is the weakest type and found in organs like the stomach
The human body is made up of several muscles that support its movement and posture. There are about 700 named muscles, and they make up roughly half of a person's body weight. These muscles are made of thousands of small fibres woven together, allowing for movement.
There are three types of muscle tissue in the human body: visceral, cardiac, and skeletal. Visceral muscle, also known as smooth muscle, is found inside organs like the stomach, intestines, liver, pancreas, and blood vessels. It is the weakest of all muscle tissues and is responsible for making organs contract to move substances through the organ, such as during digestion and nutrient collection.
Smooth muscle has a smooth, uniform appearance when viewed under a microscope, in contrast to the banded appearance of cardiac and skeletal muscles. It is an involuntary muscle, controlled by the unconscious part of the brain, and plays a role in maintaining blood pressure and flow, opening and closing airways, and regulating tissue oxygenation.
Cardiac muscle, on the other hand, is found only in the heart and is responsible for pumping blood throughout the body. Cardiac muscle is also involuntary and cannot be controlled consciously. Skeletal muscles, which are the most common type of muscle in the body, are voluntary and connect to the bones, allowing for a wide range of movements. They make up between 30% and 40% of an individual's total body mass.
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Facial muscles don't attach to bone but under the skin, allowing for small movements
The human body has over 600 muscles, with around 700 of them attached to bones. These muscles make up roughly half of a person's body weight. Most of the muscles in the body are skeletal muscles, which are voluntary muscles that move when you think about moving. They are attached to bones by tendons, which are tough connective tissues.
Facial muscles, also called craniofacial muscles, are a group of about 20 flat skeletal muscles that lie underneath the skin of the face and scalp. They are essential for chewing and making facial expressions. Unlike other skeletal muscles, they are not surrounded by fascia, with the exception of the buccinator muscle. Facial muscles are positioned around the facial openings (mouth, eyes, nose, and ears) or stretch across the skull and neck. They originate from the bones or fibrous structures of the skull and radiate to insert into the skin.
The specific location and attachments of the facial muscles enable them to produce movements such as smiling, grinning, frowning, and raising eyebrows. These muscles are commonly called muscles of facial expression, or mimetic muscles. They are innervated by the facial nerve (CN VII) and vascularized by the facial artery.
Some examples of facial muscles include the procerus, which is between the eyebrows and can pull them downward, and the orbital muscles surrounding the eyes, such as the corrugator supercilii, which enables frowning. The buccinator muscle, innervated by the buccal branches of the facial nerve, compresses the cheek against the molar teeth during mastication and helps in whistling and playing wind instruments. The zygomaticus minor arises from the zygomatic bone and inserts on the skin of the upper lip, contributing to facial expressions such as smiling, frowning, and grimacing.
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Frequently asked questions
There are more than 600 muscles in the human body, making up roughly half of a person's body weight.
There are three types of muscles: skeletal, smooth, and cardiac. Skeletal muscles are the most common and are under your voluntary control. Smooth and cardiac muscles are involuntary.
Skeletal muscles enable humans to move and perform daily activities. They also help with breathing, swallowing, and maintaining posture and balance.
The cardiac muscle is found only in the heart and is responsible for pumping blood throughout the body.
