Ligaments and tendons are both important structures in the body. Although they are sometimes confused with one another, they are two different kinds of structures. In this article we’ll help you distinguish ligaments from tendons and we’ll look at what both of these important structures do.

What ligaments and tendons have in common

Ligaments and tendons are both types of connective tissue. Both structures are composed of a greater proportion of collagen fibers than elastin fibers and both have their fibers packed in densely. This composition gives ligaments and tendons a very strong tensile strength.

What are ligaments?

Ligaments connect bone to bone. They function to stabilize and restrict the amount of movement in specific directions at a joint. Some examples of ligaments that you may have heard of are the medial collateral ligament (often abbreviated MCL) and the lateral collateral ligament of the knee (often abbreviated LCL). The medial collateral ligament prevents the bones  of the knee joint from moving too much in a medial direction. The lateral collateral ligament prevents the bones of the knee joint from moving too much in the lateral direction.

What are tendons?

Tendons connect muscle to bone. They function with muscles to create movement by moving a bone at a joint. An example of a tendon that you have probably heard of is the Achilles tendon at the ankle. The gastrocnemius and soleus muscles of the calf come together at the back of the ankle and become the strong Achilles tendon that then attaches to the calcaneus, or heel bone. When the gastrocnemius and/or soleus muscle contracts to plantarflex the foot, that action includes the involvement of the Achilles tendon.

Ligaments and tendons are connective tissue

Just like a muscle, both ligaments and tendons have layers of fascia wrapping each layer of their structure. These fascial layers are continuous with the structures that they are attached to, either bone or muscle. Ligaments and tendons are so well integrated through fascia with the structures that they attach to that if you went into the body, you would not be able to draw a line showing where muscle or bone ended and ligament or tendon began. This integration helps make both ligaments and tendons very effective at their particular functions.