The relationship between the skeletal and muscular systems by anjelicia ` murray on Prezi
Aug 14, The human muscular system includes skeletal, smooth and cardiac and various body organs produces involuntary movement essential for. Jul 4, Important Structures & Vocabulary of the Muscular System · Muscular . They move all the different parts of the skeleton. They help us in all. Mar 11, The muscular system can be broken down into three types of so the muscle serves to move parts of those bones closer to each The rhomboid major, which attaches the scapula to the spinal column, is a diamond shape.
Terms such as maximus largestminimus smallestand longus long are often used as part of a muscle's name. Still other muscles are named for their shape.
The deltoid muscle is so named because it has the shape of the Greek letter delta, which is triangular-shaped. And some muscles are named for their actions. Terms such as flexor to flex or bend inextensor to extend or straighten outadductor to draw toward a line that runs down the middle of the bodyand abductor to draw away from a line that runs down the middle of the body are often added as part of a muscle's name.
The muscles of the face are unique: Muscles that are attached to the skin of the face allow people to express emotions through actions such as smiling, frowning, pouting, and kissing.
As mentioned, the frontalis frun-TA-lis covers the frontal bone or forehead. The temporalis tem-po-RAL-is is a fan-shaped muscle overlying the temporal bone on each side of the head above the ear. It closes and extends the lips. The masseter mas-SE-terlocated over the rear of the lower jaw on each side of the face, opens and closes the jaw, allowing chewing. The buccinator BUK-si-na-torrunning horizontally across each cheek, flattens the cheek and pulls back the corners of the mouth.
The sternocleidomastoid ster-nokli-do-MAS-toydlocated on either side of the neck and extending from the clavicle or collarbone to the temporal bone on the side of the head, allows the head to rotate and the neck to flex.
Bones, Muscles, and Joints
On the front part of the trunk or torso, the pectoralis major pek-to-RA-lis MA-jor are the large, fan-shaped muscles that cover the upper part of the chest. They flex the shoulders and pull the arms into the body. The rectus abdominis REK-tus ab-DOM-i-nis are the strap-like muscles of the abdomen, extending from the ribs to the pelvis.
Better known as the stomach muscles, they flex the vertebral column or backbone and provide support for the abdomen and its many organs. In addition to helping compress the abdomen, they rotate the trunk and allow it to bend sideways. On the rear part of the trunk, the trapezius trah-PEE-zee-us are the kite-shaped muscles that run from the back of the neck and upper back down to the middle of the back.
They raise, lower, and adduct the shoulders. They adduct and rotate the arms and help extend the shoulders. Scientists have created various artificial muscles that contract and expand just like human muscles. Unlike human muscles, however, artificial muscles have no limit to their strength.
One such artificial muscle is made out of artificial silk, which is cooked and then boiled to make a rubbery, semiliquid substance. The substance is similar in structure to human muscle, composed of smaller and smaller fibers. These fibers are naturally negatively charged with electricity.
When an acid which has a positive electrical charge is applied to this substance, the negative and positive ions attract each other and the substance contracts.
When a base material which has a negative charge is applied, the ions repel each other and the material expands. A small NASA rover destined to explore an asteroid in will be equipped with artificial muscles. Scientists hope tests like this one will eventually lead to the creation of space robots with humanlike flexibility and movement.
Beyond that, they hope artificial muscles may someday be used to replace defective muscles in humans. The fleshy, triangular-shaped muscles that form the rounded shape of the shoulders are the deltoid DEL-toyd.
They help abduct the arm, or move it away from the middle of the body. Located on the front of the upper arm, the bicep makes a prominent bulge as it flexes the elbow. Its action is just the opposite of the biceps: The muscles of the forearm, which move the bones of the hands, are thin and long.
The muscles that have the opposite effect, extending the wrist and fingers, are the extensor carpi and the extensor digitorum. Muscles of the lower limbs cause movement at the hip, knee, and foot joints.
These muscles are among the largest and strongest muscles in the body. Muscles on the thigh upper portion of the leg are especially massive and powerful since they hold the body upright against the force of gravity.
These powerful muscles help extend the hip in activities such as climbing stairs and jumping. The adductor ah-DUC-ter muscles are a group of muscles that form a mass on the inside of the thighs. As their name indicates, they adduct or press the thighs together. On the front of the thigh is a group of four muscles known collectively as the quadriceps KWOD-ri-seps.
Together, the quadriceps help powerfully extend or straighten the knee, such as when an individual kicks a soccer ball. On the back of the thigh, a group of three muscles performs the opposite effect. Known as hamstrings HAM-stringsthese muscles flex or bend the knee. The sartorius sar-TOR-ee-us is long, straplike muscle that crosses the front of the thigh diagonally from the outside of the hip to the inside of the knee. Although it is not that powerful, it does lie on upper surface of the thigh and is easily seen.
The sartorius helps rotate the leg so an individual can sit in a cross-legged position with the knees wide apart. On the back part of the lower leg is the calf muscle, properly known as the gastrocnemius gas-trok-NEE-me-us.
This diamond-shaped muscle, formed in two sections, helps extend or lower the foot, such as when an individual walks on his or her toes. The strong tendon that attaches the gastrocnemius to the heel of the foot is the well-known Achilles tendon ah-KI-leez; in Greek mythologya hero of the Trojan War who is killed by an arrow shot into his heel.
The main muscle on the front part of the lower leg, the tibialis anterior tib-ee-A-lisopposes the action of the gastrocnemius. It flexes and inverts or elevates the foot. When runners and other athletes experience tenderness and pain in the front part of the lower leg, a condition commonly known as shin splints, the tibialis anterior has been strained or pulled. Almost all movements by the human body result from muscle contraction. Muscles lend support to the body and help it maintain posture against the force of gravity.
Even when the body is at rest or asleepmuscle fibers are contracting to maintain muscle tone. Finally, any activity by muscles generates heat as a byproduct, which is vital in maintaining normal body temperature. It measures just 0. Largest muscle in the body?
Longest muscle in the body? Strongest muscle in the body? Fastest-reacting muscle in the body? It contracts in less than 0. Number of muscles used to make a smile? Number of muscles used to make a frown? The link between nerve cells and muscle fibers In order to contract or shorten, muscle fibers must be stimulated by nerve impulses sent through motor neurons or nerves. These impulses originate in the brain, then run down the spine.
From there, they branch out to all parts of the body. A single motor neuron may stimulate a few muscle fibers or hundreds of them.
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A motor neuron along with all the fibers it stimulates is called a motor unit. When a motor neuron reaches a muscle fiber, it does not touch the fiber, but fits into a hollow on the surface of the muscle fiber. This region where the end of the motor neuron and the membrane of the muscle fiber come close together is called the neuromuscular junction.
When a nerve impulse reaches the end of the motor neuron at the neuromuscular junction, acetylcholine a neurotransmitter chemical is released. Acetylcholine then travels across the small gap between the motor neuron and the muscle fiber and attaches to receptors on the membrane of the muscle fiber. This triggers an electrical charge that quickly travels from one end of the muscle fiber to the other, causing it to contract.
Prior to his research, scientists knew little about the structure and function of nerves or about their interaction with muscles. A popular theory at the time even held that nerves were hollow tubes through which a spirit or fluid flowed. Haller rejected this theory, especially since no one had ever been able to locate or identify such a spirit or fluid. Instead, he sought to prove that a muscle contracts when a stimulus is applied to it.
Haller labeled this action irritability. In his research, Haller soon found that irritability increased when a stimulus was applied to a nerve connected to a muscle.
He then rightly concluded that in order for a muscle to contract, a stimulus had to come from its connecting nerve. The sliding filament theory Inwhile working to explain exactly how muscles contract, two teams of scientists developed the same theory at the same time: Today, medical researchers accept this theory as a good description of what happens to make a muscle contact.
According to the sliding filament theory, thick myofilaments have branches or arms that extend out from their main body. At the end of the branches are thickened heads the appearance of a thick myofilament can be likened to a racing shell or a long narrow boat with many oars attached on either side. Normally, when a muscle is relaxed, the thick and thin myofilaments do not interact.
When the muscle is stimulated to contract, they do. The electrical charge triggered by acetylcholine stimulates the release of calcium ions an ion is an atom or group or atoms that has an electrical charge stored within the muscle fiber. The ions attach to the thin myofilaments and remove their protective coverings. The arms of the thick myofilaments then reach out, and the heads on the arms attach to open sites on the thin myofilaments.
The arms pivot an action called a power strokepulling the thin myofilaments toward the center of the sarcomere. This shortens the sarcomere. As this event occurs simultaneously throughout all sarcomeres in a muscle fiber, the muscle fiber shortens or contracts. A single nerve impulse produces only one contraction, which lasts between 0. For a muscle fiber to remain contracted, the brain must send additional nerve impulses. When nerve impulses cease, so do the electrical charges, the release of calcium ions, and the connection between thin myofilaments and thick myofilaments.
Chief among these is the effect of weightlessness on muscles. Even after spending as little as four or five days in space, astronauts have experienced significant muscle and bone changes. The reason is that more than half the muscles in the human body are designed primarily to fight gravity. In a weightless environment, those muscles are not used.
As a result, they quickly weaken and atrophy or waste away. Without the stress of pumping blood through the body against the force of gravity, the muscles of the heart also begin to weaken considerably. Exercising during space flights is one way astronauts have tried to counter the effects of zero gravity. Unfortunately, they have had to exercise two to three hours a day just to maintain muscle and cardiovascular strength. The National Aeronautics and Space Administration NASA and research centers are currently working to develop exercising devices that recreate the forces on Earth so astronauts can spend more time exploring instead of exercising.
When a muscle fiber contracts, it does so completely and always produces the same amount of pull tension. The muscle fiber is either "on" or "off. While this principle applies to individual muscle fibers, it does not apply to entire muscles. A muscle would be useless if it could only contract completely or not at all. The amount of tension or pull in a muscle can vary depending on how many muscle fibers in that muscle are stimulated to contract.
Muscle fiber energy In order to contract, muscles need energy. That energy comes from adenosine triphosphate ATPa high-energy molecule found in every cell in the body. ATP is the only energy source that muscles can use to power their activity. Thick myofilaments need ATP in order to detach their heads from thin myofilaments. They then use the energy from the ATP to complete their next power stroke. Yet, muscle fibers store only a limited supply of ATP—about 4 to 6 seconds' worth.
For muscles to continue working, ATP must be supplied continuously. The most abundant energy source for ATP is glycogen—a starch form of the simple sugar glucose made up of thousands of glucose units. Bones are made up of two types of material — compact bone and cancellous bone.
What are the main functions of the muscular system?
Compact bone is the solid, hard outside part of the bone. This type of bone makes up most of the human skeleton. It looks like ivory and is extremely strong. Holes and channels run through it, carrying blood vessels and nerves from the periosteum, the bone's outer membrane. KAN-suh-lus bone, which looks like a sponge, is inside the compact bone. It is made up of a mesh-like network of tiny pieces of bone called trabeculae pronounced: This is where red and white blood cells are formed in the marrow.
Bones are fastened to other bones by long, fibrous straps called ligaments pronounced: KAR-tul-ija flexible, rubbery substance in our joints, supports bones and protects them where they rub against each other. Bones don't work alone — they need help from the muscles and joints. Muscles pull on the joints, allowing us to move. They also help the body perform other functions so we can grow and remain strong, such as chewing food and then moving it through the digestive system.
The human body has more than muscles. They are connected to bones by tough, cord-like tissues called tendons, which allow the muscles to pull on bones. If you wiggle your fingers, you can see the tendons on the back of your hand move as they do their work.
Humans have three different kinds of muscle: Skeletal muscle is attached to bone, mostly in the legs, arms, abdomen, chest, neck, and face. Skeletal muscles are called striated pronounced: STRY-ay-ted because they are made up of fibers that have horizontal stripes when viewed under a microscope. These muscles hold the skeleton together, give the body shape, and help it with everyday movements they are known as voluntary muscles because you can control their movement.
They can contract shorten or tighten quickly and powerfully, but they tire easily and have to rest between workouts.
Smooth, or involuntary, muscle is also made of fibers, but this type of muscle looks smooth, not striated. Generally, we can't consciously control our smooth muscles; rather, they're controlled by the nervous system automatically which is why they are also called involuntary.
Examples of smooth muscles are the walls of the stomach and intestines, which help break up food and move it through the digestive system. Smooth muscle is also found in the walls of blood vessels, where it squeezes the stream of blood flowing through the vessels to help maintain blood pressure.
Smooth muscles take longer to contract than skeletal muscles do, but they can stay contracted for a long time because they don't tire easily. KAR-dee-ak muscle is found in the heart. The walls of the heart's chambers are composed almost entirely of muscle fibers.
Cardiac muscle is also an involuntary type of muscle.The Skeletal and Muscular System
Its rhythmic, powerful contractions force blood out of the heart as it beats. Muscles and Movement Even when you sit perfectly still, there are muscles throughout your body that are constantly moving. Muscles enable your heart to beat, your chest to rise and fall as you breathe, and your blood vessels to help regulate the pressure and flow of blood through your body.
When we smile and talk, muscles are helping us communicate, and when we exercise, they help us stay physically fit and healthy. The movements your muscles make are coordinated and controlled by the brain and nervous system. The involuntary muscles are controlled by structures deep within the brain and the upper part of the spinal cord called the brain stem. The voluntary muscles are regulated by the parts of the brain known as the cerebral motor cortex and the cerebellum.
When you decide to move, the motor cortex sends an electrical signal through the spinal cord and peripheral nerves to the muscles, causing them to contract. The motor cortex on the right side of the brain controls the muscles on the left side of the body and vice versa. Sensors in the muscles and joints send messages back 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's in.
This feedback results in smooth, coordinated motion. If you want to lift your arm, your brain sends a message to the muscles in your arm and you move it. When you run, the messages to the brain are more involved, because many muscles have to work in rhythm. Muscles move body parts by contracting and then relaxing. Your muscles can pull bones, but they can't push them back to their original position.
11 functions of the muscular system: Diagrams, facts, and structure
Five fun facts about the muscular system Muscles make up approximately 40 percent of total weight. The heart is the hardest-working muscle in the body. It pumps 5 quarts of blood per minute and 2, gallons daily. The gluteus maximus is the body's largest muscle.
It is in the buttocks and helps humans maintain an upright posture. The ear contains the smallest muscles in the body alongside the smallest bones. These muscles hold the inner ear together and are connected to the eardrum. A muscle called the masseter in the jaw is the strongest muscle by weight. It allows the teeth to close with a force of up to 55 pounds on the incisors or pounds on the molars.