 Everybody, Dr. O here. In this short video, we're just going to cover the three hamstring muscles. I covered them in the thigh muscle, or the thigh video. But I also want to give you a little mnemonic device to help you remember which one's which. So the hamstrings is not a muscle. There's not anything on here called the hamstrings. It's a group of muscles, and the three muscles are the biceps femoris, the semi-tendinosis, and the semi-membranosus. And I'm saying them in that order, because the mnemonic device to remember them from lateral to medial is btm or bend towards me. So the biceps femoris is the most lateral of the three, the semi-tendinosis is in the middle, and the semi-membranosus is the most medial of the three. So bend towards me is a great mnemonic device to remember the hamstrings from lateral to medial. So the biceps femoris is called that because it's in the femoral region and has two heads. It is involved in flexion of the knee, which you can see on the screen. This is called that because it has a nice, big, flat, membranous tendon or insertion point there underneath the other muscles, but you can't see that. And then that also involved in flexion of the knee. And then semi-tendinosis has the longest tendon, the insertion point distally there under the knee. So the semi-tendinosis look for the longest tendon that travels down below the knee. Semi-membranosus, if you dissected the body or took off more muscles, you'd see this like sheath-like origin there. And then we have the biceps femoris is the one with two heads. So biceps femoris, semi-tendinosis, semi-membranosus, those are the three muscles that make up the hamstrings. And then remember, BTM or bend towards me. Biceps femoris is the most lateral, semi-tendinosis is in the middle, semi-membranosus is the most medial. I hope this helps. Have a wonderful day. Be blessed.