There are well over 600 skeletal muscles in the human body, some of which are identified in the figure below. The size of skeletal muscle varies widely, from the tiny muscles of the middle ear to the very large muscles of the thigh. You may not be thinking about a muscle part of the body, but your face has a lot of muscles. You can check them the next time you look at yourself in the mirror. Not all facial muscles attach directly to bones as they do in the rest of the body. Instead, many of them attach themselves under the skin. This allows you to contract your facial muscles a bit and make dozens of different types of faces. Even the slightest movement can turn a smile into a frown. You can raise your eyebrows to look surprised or move your nose. Smooth muscles are also found in your bladder. When relaxed, they allow you to hold in the urine (piss) until you can go to the bathroom. Then they contract so you can extract urine.
These muscles are also located in a woman`s uterus, where a baby develops. There they help push the baby out of the mother`s body when it`s time to be born. The muscles pull on the joints and allow us to move. They also help the body chew food and then move it through the digestive system. The cerebellum coordinates the muscular movements ordered by the motor cortex. Sensors in muscles and joints send messages through peripheral nerves to tell the cerebellum and other parts of the brain where and how the arm or leg is moving and what position it is in. This feedback leads to a fluid and coordinated movement. When you want to raise your arm, your brain sends a message to the muscles in your arm and you move them. When you run, messages to the brain are more involved because many muscles have to work in rhythm. In exercises such as weightlifting, skeletal muscles contract against resistance (see figure below).
Using skeletal muscles in this way increases their size and strength. In exercises such as running, the heart muscle contracts faster and the heart pumps more blood. Using the heart muscle in this way increases its strength and efficiency. Continuous exercise is necessary to maintain larger and stronger muscles. If you don`t use a muscle, it will become smaller and weaker – so use it or lose it. Did you know that you have more than 600 muscles in your body? They do everything from pumping blood through your body to help lift your heavy backpack. You control some of your muscles, while others – like your heart – do their job without you even thinking about it. When the stimulation of the motor neuron, which gives the impulse to the muscle fibers, stops, the chemical reaction that causes the proteins of the muscle fibers to rearrange is stopped.
As a result, the chemical processes in the muscle fibers are reversed and the muscle relaxes. The muscle that makes up the heart is called the heart muscle. It is also known as myocardium (pronounced: my-uh-KAR-dee-um). The thick muscles of the heart contract to pump blood and then relax to let the blood enter after it flows through the body. Together, skeletal muscles work with your bones to give your body strength and strength. In most cases, skeletal muscle is attached to one end of a bone. It extends over one joint (the place where two bones meet) and then sticks to another bone. Even when we are completely still, the muscles of the whole body are constantly moving.
Muscles help the heart beat, the chest moves up and down during breathing, and blood vessels regulate blood pressure and flow. When we smile and talk, muscles help us communicate, and when we exercise, they help us stay physically fit and healthy. Each skeletal muscle consists of hundreds, if not thousands, of skeletal muscle fibers. The fibers are grouped and wrapped in connective tissue, as shown in the figure below. Connective tissue supports and protects sensitive muscle cells, allowing them to resist contraction forces. It also provides pathways for nerves and blood vessels to reach the muscles. Skeletal muscles work hard to move parts of the body. They need a rich blood supply to provide them with nutrients and oxygen and take away their waste. Muscles can only pull and cannot press. Therefore, the muscles must work in pairs to move a joint.
One muscle contracts and pulls a joint in one direction and another muscle contracts and pulls it into the other. (2) Chemical reactions cause the reorganization of muscle fibers in such a way that the muscle is shortened – this is contraction. Now let`s talk about the type of muscles you think of when we say “muscles” – the ones that show how strong you are and allow you to throw a soccer ball into the goal. These are your skeletal muscles – sometimes called striped muscles (say: STRY-ay-tud) because the light, dark parts of the muscle fibers make them look striped (striped is a whimsical word meaning striped). The movements of your muscles are coordinated and controlled by the brain and nervous system. Involuntary muscles are controlled by deep structures in the brain and in the upper part of the spinal cord, which is called the brain stem. Voluntary muscles are regulated by parts of the brain known as the cerebral cortex and cerebellum (pronounced: ser-uh-BEL-um). When a muscle contracts (clumps), it becomes shorter, pulling on the bone to which it is attached. When a muscle relaxes, it returns to its normal size. Three types of free-moving joints play an important role in voluntary movement: But smooth muscles are at work all over the body.
In your stomach and digestive system, they contract (tighten) and relax so that food can make its journey through the body. Your smooth muscles are useful when you are sick and need to vomit. Muscles push food out of the stomach so that it passes through the esophagus (read: ih-SAH-fuh-gus) and out of the mouth. Skeletal muscles are voluntary muscles, which means you can control what they do. Your leg won`t bend to kick the ball unless you want to. These muscles help form the musculoskeletal system (say: mus-kyuh-low-SKEL-uh-tul) – the combination of your muscles and your skeleton or bone. Skeletal muscle is connected to the skeleton by hard connective tissue called tendons (see figure above). Many skeletal muscles are attached to the ends of the bones that meet at a joint. The muscles span the joint and connect the bones.
When the muscles contract, they pull on the bones, making them move. Muscles move parts of the body by contracting and then relaxing. Muscles can pull bones, but they can`t push them back to their original position. They therefore work in pairs of flexors and extenders. The flexor contracts to bend a limb on a joint. Then, when the movement is complete, the flexor relaxes and the extensor contracts to stretch or stretch the limb at the same joint. For example, the biceps muscle at the front of the arm is a flexor and the triceps at the back of the arm is an extensor muscle. When you bend over your elbow, the biceps contract. Then the biceps relax and the triceps contract to stretch the elbow. Let`s take a closer look at the stages of the mechanism of muscle contraction.
How do the bones of the human skeleton move? Skeletal muscle contracts and relaxes to move the body mechanically. Messages from the nervous system cause these muscle contractions. The whole process is called the muscle contraction mechanism and can be summarized in three steps: This exercise puts human muscles against a force. What force is it? Skeletal muscle. Skeletal muscles allow the body to move. Joints allow our body to move in many ways. Some joints open and close like a hinge (such as the knee and elbow), while others allow for more complicated movements – a shoulder or hip joint, for example, allows for backward, forward, sideward, and rotating movements. The triceps and biceps muscles in the upper arm are opposite muscles. Muscles can only contract. You cannot renew yourself or actively renew yourself. .
