Last September the newsletter kicked off with Anatomy 101. For back to school, we are going to revisit this topic with Anatomy 201. Our theme for the year is going to be muscle groups. Each month we will focus on a different “popular” muscle group. This month we are going to cover the hamstrings.
It is important to note about muscle groups, the hamstrings being a good example, that they are actually – a group of muscles. That may sound obvious but because the group name is often referred to, it can sound like it is one muscle. The general term (hamstrings) refers to multiple muscles that comprise a group.
There are three muscles in the back of thigh that make up the hamstrings. The three muscles that compose the hamstrings group are the biceps femoris, the semitendinosus and semimembranosus.
The hamstrings, all three of them, begin or have what is called their origin on the sitz bone. If you sit and put a hand underneath one hip, the bone you feel or sit on…is the sitz bone. If you practice Yamuna® Body Rolling (YBR), the sitz bone is the point that is used to begin the hamstring routine. It is also a good place to learn some of the principles of YBR as the sitz bone is one of the easier bony landmarks to find.
The biceps femoris is lateral or toward the outside of the back of the leg. It begins on the sitz bone runs along the back, outside of the leg. This muscle attaches below the knee at what is called the insertion. If you sit and bend your knee and strum your fingers along the outside edge of the back of the knee, you can feel the biceps femoris tendon as it makes its’ way to attach below the knee.
Similarly, the semitendinosus and semimembranosus are medial or run more along the inside of the back of the leg. They too attach below the knee. If you sit with your knee bent and strum along the inside back of the knee, you can feel these two tendons as they run along the back of the knee.
As the hamstrings group start at the sitz bone and run behind and attach below the knee, you can see the obvious action of the hamstrings is to bend or flex the knee. They also extend or bring the leg back at the hip joint. What may not be as obvious is how these muscles impact posture. Tight hamstrings pull on the sitz bone which pulls the pelvis down causing more of a tuck and a flat lower back posture.
Of course, tight hamstrings can make it difficult for students to sit on the floor with straight legs while keeping the back straight or when standing to reach down and touch the toes. People with tight hamstrings may try to make up for it by over rounding in their back.
All three of the muscles that comprise the hamstrings group, run from the back of the hip to the back of the knee. They impact not only knee movement but also pelvic movement and posture.
Hamstrings is a word that is often referred to but not as often given much of a detailed description. I hope defining the hamstrings has given you some clarity and insights. Please stay tuned for the continued examination into muscle groups in the next newsletter as we explore the hip flexors.