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The biceps femoris muscle is located at the back of the thigh and forms part of the hamstring group of muscles. There are two parts to the biceps femoris and only one of these is included as part of the hamstrings. This part of the muscle is known as the long head. The short head part of the muscle starts on the outer hip. Primarily, both heads of the biceps femoris muscle help to flex the knee.
The two heads of the muscle differ in origin. The long head starts toward the bottom of the lower back and joins via a tendon, which it shares with another muscle called the semitendinosus. This is known as the long head as the point of attachment is much higher and further away from the insertion than the short head. Another purpose of the long head biceps femoris is to laterally rotate the hip when there is flexion of the knee.
In contrast to the long head, the short head attaches to the thigh bone. It therefore is much shorter than the long head although it still provides the same function — flexion of the knee joint. Both the long head and short head insert at the same tendon on the lateral side of the knee.
The biceps femoris muscle forms part of one of the largest muscle groups in the body — the hamstrings. Generally the name hamstrings is given to any of the three muscles located on the back of the thigh but is also used to describe tendons in the same location. The other two muscles that make up the hamstrings are the semiteninosus and semimembranosus.
Hamstring injuries are common among athletes due to the large amount of strain that can be transmitted through this muscle. Injuries are often more common in tall people who have naturally tight hamstring muscles. Hamstring injuries are notorious for being difficult to overcome as it can be hard to avoid re-injuring the muscle during day-to-day activities.
One of the most effective ways of avoiding hamstring muscle tears is to regularly stretch the muscles. This can be performed in a number of different ways although the stretcher should be careful to avoid overstretching. An example of a hamstring stretch is to use a towel or long exercise band to raise up the straight leg while lying in a supine position. Stretches should be held for a minimum of 20 seconds.
I always thought biceps were muscles in the arm, but when I looked it up the word "biceps" actually means "two heads" and refers to the fact that this muscle has two separate parts that both attach to the same place.
And the bicep in the arm, which is what I usually think of when I hear the term "biceps" is the same deal, with two separate fiber bundles.
Another little fact about the word is that when you say biceps you don't necessarily mean "two or more biceps" with bicep as the single (although people do sometimes say bicep). Biceps is actually the singular and the plural.
So now you can correct people if they get their muscles wrong.
@bythewell - I don't even think you need to wait until you've exercised in order to stretch. You might want to go gently at first if your muscles aren't warm, but otherwise you can stretch any time.
My favorite hamstring stretch is putting my heel up on something like the back of a chair at waist height, and then leaning into my foot from the hips. At first I could barely touch my toes, but after a while I began to be able to lean right across the leg.
I'm quite proud of that, actually. I can kick much higher as well!
One thing that I don't think get emphasized enough is that studies have shown that you should not stretch before exercising.
You should definitely warm up your muscles, maybe with light jogging, or even with what's called dynamic stretches (which are stretches that include movement, like rotating your ankles), although you should even take it easy on those.
The reason is that if your muscles are too loose when you exercise they might overextend and you can injure yourself that way.
You should stretch after exercise, in order to get the best benefits. And people almost always need to stretch out their hamstrings, so definitely go for it.
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