The Musculoskeletal System: How Do We Move
The Musculoskeletal System
The musculoskeletal system is made up of lots of different parts such as bones, muscles, cartilage, ligaments, tendons that form a framework for the body. There are 206 bones in the adult skeleton but the male and female musculoskeletal system are not the same. The female skeleton has a broader pelvis to meet the needs of childbirth whereas the male skeleton is typically taller with a larger bone density. The skeleton is divided into two types: the axial skeleton and the appendicular skeleton. The axial skeleton includes bones that form the skull, ribs, and vertebral column whilst the appendicular skeleton includes the bones of the rest of the skeleton-like the shoulders, the upper and lower limbs, and the pelvis.
The bones in the skeleton are not all solid, some bones are solid bone with a few canals whereas some bones have a honeycomb-like structure. Bones provide five main functions for the body: support, movement, protection of internal organs, storage of minerals and fat and production of blood cells. They provide the body’s structure; this structure the body maintain its shape. They provide movement by the bones acting like a lever and form joints. These joints allow the muscles to pull on them and therefore create movement. Even though bones are light they are strong enough to support the entire weight of our bodies. For example, the skull protects our brains whilst also forming the shape of the face. They are made up of a framework called collagen with a mineral called calcium phosphate that makes the framework strong. They also store calcium and release it into the bloodstream when its needed by other parts of the body. Bone marrow which is a spongy tissue inside of the bones produces blood cells such as red and white blood cells. There are 5 major bones which are long, short, irregular, flat, and sesamoid bones.
Long bones are can come into many sizes such as the femur, the longest bone in the body, to the small bones in your fingers. Their function is to support the weight of the body and help with movement. Short bones are shaped like cubes that contain mostly spongy bones. Their function is to provide stability and some movement. Irregular bones have different, complex shapes and vary in shape. Their function is to protect organs. Flat bones thin, flattened bones with two layers of compact bones and a layer of spongy bones. Their function is to protect organs or provide areas of attachment for muscles. Sesamoid bones are small round bones embedded within tendons. Their function is to protect tendons from stress and wear.
A muscle consists of muscle tissues packed together and surrounded by epimysium, a tough connective tissue like cartilage. The epimysium surrounds bundles of nerve cells that run along the fibres called fascicles. Muscles can give you mobility by either producing fast-twitches or short-twitches, fast-twitches are used for small movements for short bursts of speed or strength and then slow-twitches work better for longer movements. Muscles also contribute to circulation, one example of this is the cardiac muscle that surrounds the walls of the heart. Cardiac muscle is made up of smooth muscle which helps your heartbeat and blood flow through your body. It does this by creating electrical impulses. They can also help with stability by your core muscles in the abdomen, back, and pelvic muscles, the stronger these muscles are the more it helps stabilize.
Cartilage is made of many different things like collagen, fibres and sometimes, elastin. The main function of cartilage is to connect bones together, but it can also be found in joints. It can also create a plane which can help bones form when they first develop. Ligaments is made from dense bundles of collagenous fibres and spinal shaped cells. These spinal shaped cells are connective tissue in ligaments that protects these structures and prevents them from twisting and tearing. Regardless of whether they connect to bones or organ, they help maintain stability. Tendons are composed of dense connective tissue mostly made up of fibres. They are also connective tissues which attaches muscle to bone, but they can be found connecting muscles to structures such as the eyeball.
How do we Move?
The bones form joints that act as levers allowing muscles to pull on them to produce movement. A joint is the part of the body where two or more bones meet. They are made to allow for different types of movement, and they make the skeleton flexible. They allow our bodies to move in many ways, there are two ways to classify joints: based on their structure their function. Joints have a complex structure made up of bones, muscles, cartilage, and ligaments. they are designed to bear weight and help move the body. Cartilage covers the surface of a bone at a joint and helps reduce the friction of movement. Ligaments, especially in the joins, are like a strong firm attached straps or ropes. They stabilize the joint or hold the ends of two bones together. Joints bind the skeleton together, to give structure and allow muscles to move bones. A type of joint is a synovial joint which allow for smooth movements between adjoining bones. They are also surrounded by an articular capsule that defines a joint cavity filled with synovial fluid. There are six major joints which are the pivot, hinge, saddle, plane, condyloid and ball-and-socket joints.
Pivot joints are a type of synovial joints that permit axial rotation. The pivot joint consists of the rounded end bone fitting into a ring formed by the other bone and ligaments. This structure allows rotational movement, as the rounded bone moves around its own axis. An example of a pivot joint is the joint of the first and second vertebrae of the neck that allows the head to move back and forth.
Hinge joints is another type of synovial joint that exists in the body which allows motion in one plane. They e ease bending and straightening actions, such as flexing a finger. In a hinge joint, cartilage covers the bone, and a thick gel called synovial fluid lubricates them. This allows them to move without rubbing against one another. Examples of these joints include ankles, elbows, fingers, knees, and toes.
Saddle joints are a type of synovial joint that allows connection between two bones. A saddle joint is where one of the bones forming the joint is shaped like a saddle while the other bone resting on it. They provide stability to the bones while providing more flexibility than a hinge joint. The best example of a saddle joint is trapeziometacarpal joint at the base of the thumb which connects the trapezium and metacarpal bones of your thumb.
Plane joint are a type of synovial joint between flat and near-flat surfaces. These joints allow the bone to slide or rotate against each other, but the range of motion is usually slight and tightly by the ligaments surrounding the bones. Examples are the joints between the metacarpal bones of the hand and those between the cuneiform bones of the foot.
Condyloid joints are another type of synovial joint which consists of an oval-shaped end of one bone fitting into another oval-shaped hollow of another bone to allow angular movement along two axes. This permits movement in two planes, allowing flexion, extension, adduction, abduction, and circumduction. The radiocarpal joint or also known as the wrist joint is an example of a condyloid joint.
The ball-and-socket joint provides swinging and rotating movement. The bone is received into the cavity of another bone, allowing the bone to move around three main axes with a common centre. This joint is made up of a round end of one bone that fits into a small cup-like area of another bone. This joint has stabilizing ligaments that limit directions in which the bones can be moved. An example of a ball-and-socket can be found in the hip, that connects the femur to the pelvis.
Muscles, ligaments, and tendons also help with the process of movement. Muscles move the body parts by contracting and then relaxing. They can pull bones but then the bones cannot be pushed back into its original position. So, the muscles work in pairs of flexors and extensors. The flexor contracts to bend the limb at the joint. When the movement is completed, the flexor relaxes and the extensor contracts. This is to extend or straighten the limb at the same joint to get the limb back to its original position. For example, the biceps muscle. In the front of the upper arm, is a flexor, and the triceps, at the back of the upper arm, is an extensor. When you bend at your elbow, the biceps contracts then the biceps relax so the triceps can contract to straighten the elbow back out. Ligaments are fibrous cords composed of connective tissue that contains collagen and elastic fibres. The elastic fibres allow the ligaments to stretch to some extent. Ligaments surround joints and bind them together; they also help strengthen and stabilize joints by permitting movement in certain directions. The bones connected to the muscles cause the bones to move when the muscles tighten and relaxes, the tendons then act as connectors that transfer the movement of the muscle. One end of the tendon is attached to a muscle then the other end is firmly attached to the membrane covering the one.