Updated Feb 28, 2025
This kit was created to assist you in completing The Human Locomotor System Challenge Kit. Included are facts, stories, crafts, games, recipes and information that can be copied and distributed to the participants working on this kit.
No two bones are exactly alike. Many have a matching mirror image, but none are identical. A bone is stronger than a steel bar if the same weight. The smallest bone is the stapes bone in the middle ear. The longest bone is the femur, which is the thigh bone.
Locomotion means moving from place to place. The locomotor system, also known as the musculoskeletal system, consists of the bones that form the skeleton, the skeletal muscles, the joints, and the connective tissues. It is an intricate system that coordinates to facilitate body motion.
Hundreds of muscles have to pull on bones and flex or stabilise joints to perform even the simplest of movements. Along with enabling it to move, the locomotor system also gives the human body its basic shape.
Together, the bones of the human body form the skeleton. The skeleton supports the body, providing its framework. Its most important job is to protect the internal organs. The skull protects the brain, the ribs guard the heart, lungs, liver and stomach, and the pelvis shields the bladder and reproductive organs. Bones grow in many different shapes, of which there are three types:
Long bones are long and slim with wider, knobby ends. These bones are located in the limbs, fingers and toes allowing the legs to walk, the arms to reach and the fingers to point.
Flat bones come in various shapes and dimensions and are thin, broad and generally curved, like plates. Examples of flat bones are the sternum (breastbone), the ilium (pelvis) and most of the bones of the cranium (skull).
Short bones are small in size and either tubular or cubic in shape. The easiest way to identify them is that they are as wide as they are long. Their primary function is to provide support and stability to the body without moving very much. Examples of these bones can be found in the feet (tarsal bones), the hands (carpal bones), the wrists and the ankles.
Bones are made up of calcium, phosphorus, sodium, and other minerals, as well as the protein collagen. Calcium is needed to make bones hard, which allows them to support your weight. Bones also store calcium and release it when other parts of the body need calcium. The amounts of certain vitamins and minerals that you eat, especially vitamin D and calcium, directly affect how much calcium is stored in the bones.
Bones are dynamic, meaning that they react to stress, such as exercise, by growing thicker and denser. Conversely, bones that are not kept active become weak and brittle. It is extremely important that bone mass is stored up during a person’s youth because bone mass is gradually lost throughout adulthood. In this way, bone health later in life requires that a person build optimal bone mass in the first 20 years of their life.
Ninety percent of bone growth takes place between the ages of 10 and 20, making youth a critical time for accumulating bone mass via diet and exercise. Osteoporosis is a disease characterized by low bone mass that thins and weakens bones, making them more likely to break. It usually happens to people later in life and can often be avoided by the preventative steps already mentioned.
Bones are made up of three layers. Compact bone is the strong, hard outside layer that acts as a protective “shell.” Beneath the compact bone is the layer of cancellous bone, which is a lightweight, spongy material resembling a honeycomb structure. Bone marrow fills the centre of the bone and looks like red or yellow jelly. Bone marrow produces red blood cells.
A broken bone is called a fracture. Bone fractures can occur as a result of a fall or a trauma that causes a violent impact, such as a car accident. The good news is a broken bone can heal if the two (or more) broken ends are brought back together and kept in place.
A cast will hold the broken bones in position while the two ends of the broken bone build layers of new bone to reconnect the broken pieces. If the bone is shattered (broken in many places), metal pins and screws might be needed as well to better stabilize the bone as it heals. It can take up to 12 weeks for bones to repair themselves and several more months after that for the bone to be as strong as it was before the fracture.
Babies are born with more than 300 bones, some of which fuse together over time. Fully grown adults usually have 206 bones arranged in symmetry.
Skeletal muscles are fleshy masses of muscle fibres arranged in bundles. The human body has around 650 skeletal muscles of varying size and ability. Skeletal muscles are those muscles which you can consciously control and move because they are attached to the skeleton, not the ones that work on their own like the heart.
Muscles can only move in one direction; they can pull by contracting (shortening from their resting length), but they cannot push. Consequently, skeletal muscles work in pairs. One muscle will contract, pulling on the bone in one direction, while the other muscle relaxes and stretches out, pulling in the opposite direction.
For example, the bicep and tricep muscles of the front and back of the upper arm work as a pair. When the forearm extends, the bicep relaxes and the tricep contracts. When the forearm bends, the bicep contracts and the tricep relaxes. In this way, the contractions of muscles are responsible for the movements of the body.
The shape of a muscle changes based on the action it receives. Muscles grow larger by repeatedly stretching and contracting against resistance, such as gravity or extra weight. The more you use a muscle, the stronger it gets. Likewise, muscles shrink from disuse, as well as from malnutrition, disease and the natural aging process.
Muscles are made primarily from protein-building blocks called amino acids. Therefore, it is important to eat protein to keep your muscles healthy. When you eat protein, the amino acids (and other nutrients) travel from your bloodstream into the muscles to support them.
Strains are common muscle injuries. A strain is a muscle that has been over-stretched, most commonly in the back, neck, or leg muscles. Strains often happen when a muscle is pressured or pushed too far, such as when lifting an object that is too heavy.
Proper warm-ups and stretching before strenuous exercise can greatly reduce the chance of strain. A strained muscle will be tender, swollen, and possibly bruised, but it will heal on its own with rest and ice.
The buttocks muscle, called the gluteus maximus, is the largest muscle. The smallest muscle is the stapedius, also in the middle ear. The masseter, which opens and closes the jaw, is the strongest muscle of the body.
Joints are the places where the bones of the skeleton make contact and fit together. The human body has more than 200 joints, and that is a good thing because, without joints, the skeleton cannot move. Joints have to work smoothly to prevent damage and discomfort.
Arthritis is a general term for joint swelling and inflammation, causing pain, stiffness and disability. Arthritis occurs due to the deterioration of joint cartilage, leaving the ends of bones in direct contact with each other. There are different kinds of arthritis, but most affect adults over the age of 55.
There are three main types of joints based on their range of mobility and specific function:
True to their name, fixed joints do not move. They are simply a solid contact point between two or more bones. They provide a protective layer for the body’s soft tissues. For example, the joints of the skull are fixed, which protects the brain.
Semi-mobile joints permit slight movements, rather than fusing the bone surfaces together. For example, the joints of the spine allow forwards, backwards and sideways bending.
Mobile joints allow a wide range of motion and are the most common type of the three. The joints of the limbs are mobile joints including the shoulders, hips, elbows and knees.
Mobile joints are distinguished from each other by their shape and the way they link bones together to let the skeleton bend and stretch in different ways.
Ball and socket joints allow for the broadest range of movements, including twisting and swivelling. In a ball and socket joint, one bone rotates like a ball inside a cup-like socket (indent) at the end of another bone. Examples of ball and socket joints are the hips and shoulders. Hinge joints work like a door hinge or lever, moving backward and forward in a single direction. Examples of hinge joints are the knees, elbows, fingers and toes, which are all appendages that can extend and retract.
Pivot joints allow for rotation around an axis, as is found at the top of the spine, allowing the head to turn.
Saddle joints are found only in the hands, located at the bases of the thumbs. The saddle joint in each thumb allows it to move in a wide circle. In gliding joints, bones just glide over each other, like in some of the ankle and wrist joints.
Just like with the bones and muscles there are things we can do to keep our joints healthy. Firstly, maintaining a healthy body weight is extremely beneficial. Being overweight or obese puts increased stress on the joints, especially the hips, knees, back and feet. For example, every extra pound puts four times the pressure on the knees. Additionally, maintaining good posture protects the joints in your neck, back, hips and knees. Exercise is important as well.
Moving around and changing positions regularly will decrease the stiffness in the joints and strengthening the muscles around the joints keeps the joints from rubbing against one another, wearing down cartilage. Gently range-of-motion exercises like stretching, yoga, pilates and tai chi are a good way to keep muscles and ligaments flexible, limber and strong. Heavy periods of physical activity should be followed by rest. Repetitive stress on joints for long periods of time can accelerate the wear and tear that causes osteoarthritis.
The human body has more than 200 joints, which move in different ways. Except for your tongue and eyebrows, none of your body parts could move without joints.
Connective tissue supports, anchors and connects the various parts of the locomotor system. Without them, the bones and muscles would be disjointed and unable to move. There are three main types of connective tissue in the locomotor system:
Ligaments are tough bands of fibrous elastic tissue that stretch across or around a joint and connect one bone to another. They are made up of collagen. Ligaments help to limit dislocation and prevent certain movements such as hyper extension (the bending backwards of a joint beyond its normal range). Ligaments will progressively lengthen for as long as they are under pressure. Overstretched or twisted ligaments can be susceptible to tearing, which results in a sprain. Sprains occur most often in athletes who exercise rigorously.
Tendons are tough cords of fibrous tissue made up of collagen, just like ligaments, except that they attach muscle to bone or muscle to muscle and are even more stretchy. Tendons and muscles work together to use bones as levers to perform movements and maintain posture. Tendon injuries can also occur due to overuse.
Cartilage is a strong but flexible tissue in the joints that covers the surface of the ends of bones to protect and cushion them from rubbing against each other. It is softer and more slippery than bone and can change and grow faster, but is also more easily damaged. Cartilage is found in knee joints.
The largest single joint is in the knee. The most mobile joint is the shoulder The most immobile joint is the sutures of skull. The hip joint is the strongest joint in the body.
Once you have finished this challenge kit, use code ECK019 for 20% off the Human Locomotor Badge!
This Meeting Plan was researched and written by our intern Vanessa Day.
