Logan Steele
There are over 600 muscles in the human body, and they all look different. Skeletal muscles, which are the most common type, are striated or striped, with red and white fibres. Cardiac muscles are also striated, but smooth muscles are not. Smooth muscles have a very smooth, uniform appearance when viewed under a microscope. Skeletal muscles vary in size, shape, and arrangement of fibres, and they can be broad or narrow in shape. They can be attached to one or more bones and have abundant blood vessels and nerves. Cardiac muscles are found in the heart and are responsible for pumping blood throughout the body. Smooth muscles line the inside of some organs and help with essential functions like moving waste through the intestines.
| Characteristics | Values |
|---|---|
| Number of muscles in the human body | More than 600 |
| Muscle tissue types | Three: skeletal, cardiac, and smooth |
| Skeletal muscle fibres | Red and white |
| Skeletal muscle appearance | Striated or striped |
| Cardiac muscle appearance | Striated |
| Smooth muscle appearance | Smooth and uniform |
| Muscle pain | Sore or achy |
| Muscle weakness | Stiffness, trouble breathing, coughing, and closing eyelids |
| Muscle groups | Shoulders, upper arms, calves, face, back, neck, arm, abdominal, hamstring, quadriceps, biceps, triceps |
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What You'll Learn
- Skeletal muscle fibres are red and white, striped and attached to bones
- Cardiac muscle is striated, found in the heart and involuntary
- Smooth muscle is involuntary, found in visceral organs and has a smooth appearance
- Muscle pain and stiffness can be a sign of muscular dystrophy
- Muscles vary in size, shape and direction, e.g. triangular deltoids
Skeletal muscle fibres are red and white, striped and attached to bones
There are more than 600 muscles in the human body, and they help us move, breathe, swallow and stay alive. Skeletal muscles are the most common type of muscle in the body, comprising 30% to 40% of our total body mass. They are attached to bones and allow us to perform a wide range of movements and functions.
Skeletal muscles are voluntary muscles, meaning we control how and when they move and work. They are attached to bones directly or through tendons or aponeuroses. Tendons are tough bands of connective tissue that attach skeletal muscle tissue to bones. Tendons intertwine with the collagen of another tendon at one end and fuse with the periosteum coating the bone at the other end. The tension created by the contraction of muscle fibres is transferred through the connective tissue layers to the tendon and then to the periosteum, enabling the movement of the skeleton.
Skeletal muscle fibres are red and white, and they have a striped appearance due to the arrangement of sarcomeres. They are also known as striated muscles. Each muscle can contain thousands of fibres, and these fibres usually span the length of the muscle. The fibres contract, allowing the muscles to move bones so we can perform different movements.
Skeletal muscles are made up of long, multinucleated cells. The membrane of the cell is the sarcolemma, and the cytoplasm of the cell is the sarcoplasm. The sarcoplasmic reticulum (SR) is a form of endoplasmic reticulum. Muscle fibres are composed of myofibrils, which are made up of sarcomeres linked in series. The striations of skeletal muscle are created by the organisation of actin and myosin filaments, resulting in the banding pattern of myofibrils.
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Cardiac muscle is striated, found in the heart and involuntary
There are over 600 muscles in the human body, which help us to move, breathe, swallow and stay alive. Some muscles are visible and can be felt, while others, like the heart, are constantly working in the background.
The three types of muscles in the body are skeletal, cardiac and smooth muscle. Skeletal muscles are voluntary muscles, meaning we can control how and when they move. They are attached to the bones and allow us to perform a wide range of movements. Cardiac and smooth muscles are involuntary, meaning they work without our conscious input.
Cardiac muscle, also known as myocardium, is striated and found only in the heart. It makes up the middle layers of the heart and is responsible for pumping blood around the body. The heart is a vital organ, and its muscle tissue is strong and powerful. Cardiac muscle contracts and relaxes in short, intense bursts, and its fibres are packed into highly regular, repeating arrangements of bundles.
Cardiac muscle is involuntary, meaning it beats on its own without our conscious control. The heart is part of the autonomic nervous system, which controls our body's unconscious functions. The cardiac action potential is generated involuntarily through a process called excitation-contraction coupling (ECC). This process involves electrical impulses and calcium channels, which trigger the contraction of the heart muscle.
Overall, cardiac muscle is a unique and specialised type of striated muscle that plays a crucial role in human physiology by ensuring the continuous circulation of blood throughout the body.
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Smooth muscle is involuntary, found in visceral organs and has a smooth appearance
There are three types of muscles in the human body: skeletal, cardiac, and smooth muscle. Skeletal muscles are the most common type of muscle in the human body and are attached to bones. They are also the only type of muscle that is under voluntary control.
Smooth muscle, on the other hand, is involuntary and is found in the walls of visceral organs such as the stomach, intestines, urinary bladder, uterus, and blood vessels. It is called smooth muscle because, unlike skeletal or cardiac muscle, it does not have a striped appearance but instead has a very smooth, uniform appearance when viewed under a microscope.
Smooth muscle consists of thick and thin filaments that are not arranged into sarcomeres, giving it a non-striated pattern. On microscopic examination, it appears homogenous. The shape of smooth muscle is described as fusiform, which means it is round in the centre and tapers at each end.
Smooth muscle plays an important role in many organ systems, including the gastrointestinal tract, where it helps propel food through the system, and the cardiovascular system, where it regulates blood flow and pressure. It is also found in the eyes, where it changes the size of the iris and alters the shape of the lens, and in the skin, where it causes goosebumps.
The nervous system uses smooth muscle to regulate many of the body's subsystems without any conscious thought. For example, during exercise, the body adapts to increasing oxygen demands by adjusting blood pressure without any conscious input. Smooth muscle is also important in the disease process, with medications targeting smooth muscle to treat conditions such as asthma and gastric emptying issues.
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Muscle pain and stiffness can be a sign of muscular dystrophy
The human body has over 600 muscles, which are pieces of soft tissue that help us move, breathe, swallow, and stay alive. There are three types of muscles: skeletal, cardiac, and smooth muscle. Skeletal muscles are the most common type of muscle in the human body and are attached to the bones, allowing for a wide range of movements. These muscles are voluntary, meaning we can control how and when they work. Cardiac muscles, on the other hand, are involuntary and make up the middle layers of the heart, responsible for pumping blood through the cardiovascular system. Smooth muscles are also involuntary and line the inside of some organs, aiding in functions like moving waste through the intestines and helping the lungs expand during breathing.
- Duchenne muscular dystrophy (DMD): The most common form that mainly affects boys but can also occur in milder forms in girls. It affects the heart and lungs as it progresses.
- Becker muscular dystrophy (BMD): The second most common type, usually milder than DMD, with symptoms typically appearing between the ages of 5 and 60.
- Emery-Dreifuss muscular dystrophy (EDMD): This type primarily affects male children and young adults, causing muscle weakness in the shoulders, upper arms, and shins. It can also impact the heart.
- Facioscapulohumeral muscular dystrophy (FSHD): FSHD commonly affects muscles in the face, shoulders, and upper arms, and can cause severe pain in the affected limbs.
If you are experiencing persistent muscle pain and stiffness, it is important to consult a healthcare provider. They can help diagnose any underlying conditions and provide guidance on maintaining muscle health through exercises, movements, or physical activities.
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Muscles vary in size, shape and direction, e.g. triangular deltoids
The human body has over 600 muscles, which vary in size, shape, and direction. These muscles are pieces of soft tissue that help us move, breathe, swallow, and stay alive. They can be categorised into three types: skeletal, cardiac, and smooth muscle.
Skeletal muscles are the most common type of muscle in the body and are attached to the bones, allowing for a wide range of movements. They are also the only type of muscle that can be controlled consciously. Skeletal muscle fibres are red and white, giving them a striped appearance. They comprise 30% to 40% of our total body mass.
Cardiac muscles, on the other hand, make up the middle layers of the heart and are responsible for pumping blood throughout the body. They are involuntary muscles, meaning they contract and relax without conscious control. Cardiac muscles also have a striped appearance.
Smooth muscles line the inside of some organs, such as the intestines and lungs, and play a crucial role in moving waste and aiding in breathing. They are involuntary muscles with a smooth, uniform appearance when viewed under a microscope.
Deltoid muscles, for example, are thick, triangular skeletal muscles that cover the top of the shoulder. They get their name from their resemblance to the Greek letter 'delta' (Δ). These muscles have a broad origin and a narrow base, contributing to their triangular shape. The deltoids work with other shoulder muscles, such as the rotator cuff muscles, to enable various movements like arm abduction and flexion. They also help stabilise the shoulder joint to prevent dislocations.
The variation in muscle size, shape, and direction allows them to fulfil specific functions and adapt to the unique anatomical requirements of different body parts.
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Frequently asked questions
Muscles are pieces of soft tissue that help you move, breathe, swallow and stay alive. There are over 600 muscles in the human body.
There are three types of muscle tissue: skeletal, cardiac, and visceral (or smooth). Skeletal muscles are red and white and look striated or striped. Cardiac muscles are also striated. Smooth muscles, on the other hand, have a very smooth, uniform appearance when viewed under a microscope.
Skeletal muscles are the most common type of muscle in the body. They include shoulder muscles, hamstring muscles, and abdominal muscles.
Cardiac muscles are found only in the heart. They make up the middle layers of the heart and are responsible for pumping blood throughout the body.
Smooth muscles line the inside of some organs, such as the stomach, intestines, and blood vessels. They play an important role in many body systems, including the reproductive and urinary systems.
