Bones, Ligaments, Menisci and Muscles

For Young Learners

Structure and Location

Almost everything in your knee belongs to one of four groups.

Bones give the shape. The thigh bone from above, the shin bone from below, the kneecap at the front, the fibula on the outside. They are hard, they do not bend, and they set where everything else attaches.

Ligaments are tough cords joining bone to bone. Two sit inside the joint and cross over each other, which is how they got the name cruciate, from the Latin for cross. Two more run down the sides. Together they stop the bones going where they should not.

Menisci are two rubbery pads shaped like the letter C. They sit on top of the shin bone, between the two bones, and the rounded end of the thigh bone settles into them.

Muscles pull on bones to make them move. The big group at the front straightens your knee. The group at the back bends it. They are joined to the bones by tendons, which are like ligaments except they connect muscle to bone instead of bone to bone.

Function

Think of a tent. The poles are the bones. The guy ropes are the ligaments, holding the poles where they should be. The groundsheet underneath, spreading the load, is like the menisci. And someone pulling the ropes tighter or looser as the wind changes, that is the muscles.

No tent stands on poles alone, and no knee works on bones alone.

Each group also fails differently. Bones break. Ligaments tear. Menisci split. Muscles strain. Knowing which group is involved tells you roughly what to expect, long before anyone mentions a scan.