It can happen in the blink of an eye. Something snaps in your knee, your shoulder hurts. The result? We feel pain in our musculoskeletal system – that ‘device’ we use throughout our entire lives which deserves to be well looked after. Learn more about the coordinated movements of over 200 bones, joints, ligaments, tendons and muscles. Find out more.
The musculoskeletal system consists of over 200 bones. But bones are just the beginning. From joints to muscles, ligaments and tendons, the bigger picture is much more complex. Read on to find out what functions these various parts perform and how they all work together.
Muscles are cells that facilitate movement by contracting and relaxing. Movement is triggered by a message from the brain, which travels through the spinal cord and nerves to the muscles.
Humans have three types of muscle tissue:
- Skeletal muscles, diagonally striped muscles: these are responsible for conscious movements, such as raising an arm. We control them with our thoughts.
- Smooth, involuntary muscles: These are found in internal organs, such as the digestive tract. We cannot control their movements, as they are part of the autonomic nervous system.
- Cardiac muscle: This type of muscle tissue also has diagonal stripes, but unlike skeletal muscle, it contracts independently and rhythmically (to make the heart beat).
The bony skeleton holds the human body together and is composed of over 200 bones of different shapes and sizes. From the tiny bones in our ears to the sturdy thigh bones – they all have to work together in perfect coordination to keep us moving as we should.
Joints are connections between two or more bones that enable different kinds of movement. But did you know that there are true joints and so-called ‘false’ joints?
True joints have a space between the ends of the bones. This joint space is located in a joint cavity, which is surrounded by a joint capsule. The ends of the bones are covered in articular cartilage and ligaments help to guide the movements of the joint. True joints give us mobility.
False joints, in contrast, tend to be stiff and provide stability. So they are built differently to true joints:
- Some are fibrous joints, such as the connection between the shin bone and the calf bone, which are joined by a dense connective tissue.
- The spinal discs are an example of cartilaginous joints. As the name suggests, these joints are joined by various types of cartilage tissue.
- And bony joints are joints like the sacrum and the coccyx (tailbone) – these two vertebrae are actually fused together.
The bones on either side of a joint are joined by ligaments. These firm and fibrous strands of connective tissue are not very elastic and so provide stability for the joint. If you twist your ankle, the ligaments can overstretch or tear, however they can also protect the ankle from becoming dislocated. Ligaments also hold the internal organs in place inside the chest and abdomen.
Tendons connect the end of a muscle to a bone, so they are essentially a continuation of the muscle. Muscle contractions are transferred through the tendons to the bones and the bones move against each other in the joint, resulting in movement. Tendons are incredibly tear-resistant.
They are encased inside tendon sheaths, which are like tunnels composed of connective tissue filled with a lubricating fluid. The sheaths make it easier for the tendons to slide back and forth, and protect them against excessive friction. Tendons are particularly pronounced in places where they run across multiple joints.