Tendons don't move on their own; they facilitate movement by transmitting the force generated by muscle contractions to the bones. When a muscle contracts, the tendon pulls on the attached bone, causing it to move.
Tendons: The Link Between Muscles and Bones
Tendons are strong, fibrous connective tissues that connect muscles to bones. They are essential for movement because muscles alone cannot directly attach to and move bones. Think of them as ropes that allow your muscles to pull on your skeletal system.
How Tendons Facilitate Movement
The mechanism of tendon-mediated movement can be broken down into the following steps:
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Muscle Contraction: A signal from the nervous system triggers a muscle to contract (shorten and generate force).
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Tendon Tension: As the muscle contracts, it pulls on the tendon to which it's attached. Because tendons are stiffer than muscles and have great strength, they efficiently transmit the force.
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Bone Movement: When you contract (squeeze) your muscle, your tendon pulls the attached bone, causing it to move. The tendon acts as a lever, transferring the force to the bone and causing it to rotate around a joint.
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Release and Relaxation: When the muscle relaxes, the tension on the tendon decreases, and the bone returns to its original position (or is moved by another muscle/tendon combination).
Example of Tendon Movement: Bicep Curl
Consider the bicep curl exercise:
- Your bicep muscle (located on the front of your upper arm) contracts.
- The bicep tendon, which connects the bicep muscle to bones in the shoulder and forearm, becomes taut.
- The tendon pulls on the forearm bone (radius and ulna), causing your elbow to flex and your hand to move towards your shoulder.
Characteristics of Tendons
- Strength: Tendons are incredibly strong, allowing them to withstand significant forces without tearing.
- Stiffness: Tendons are stiffer than muscles, allowing for efficient force transmission. This stiffness ensures minimal energy loss during muscle contraction.
- Limited Elasticity: While tendons possess some elasticity, their primary function is to transmit force, not to store and release energy like ligaments.
