There are 3 muscles that make up the hamstrings. Together they help to bend the knee, extend and rotate the hip. The hamstrings play a key role keeping the body healthy. They greatly help support and protect both the knee and the back. The tighter and weaker the hamstrings are, the greater amount of strain there is at these joints. The hamstrings are weaker than the quadriceps by about 30%; this is one reason why hamstrings are more frequently strained. Sprinters will work the upper hamstrings (and “glutes”) to help increase their running power (acceleration).
This is the largest and strongest of the hamstrings. Tightness in this hamstring can be found to be associated with “sciatica”. The sciatic nerve lies below the biceps femoris, in addition a branch of the sciatic nerve curves around a bone that the muscle attaches to. So the tighter the hamstrings (biceps femoris) the more pressure that can be placed on the sciatic nerve.
The tendon from this muscle is sometimes used in ACL repairs. The tendon is used to replace the torn ACL ligament.
The piriformis is a muscle that needs to be mentioned for it often plays a role in back and posterior leg pain. The reason for this that the sciatic nerve either passes through or under the piriformis muscle so the tighter the piriformis the more pressure is placed upon the sciatic nerve which can lead to butt, thigh or leg pain.
A nerve common to the back of the leg is the “sciatic nerve”. This nerve exits the back and runs all the way down the leg, so a common place to have pain is in the back of the leg. Now depending on your body’s position and your activity, you may feel pain in the buttock, the back of the leg or all the way down into your foot.