Many people make the mistake of referring to a single muscle that runs vertically over your hip joint as the Hip Flexor. In reality, this is just one of many muscles that form the muscle group that we’ll learn about in this short guide.
What do the Hip Flexors Do?
Before we get into the basic anatomy of this muscle group, let’s briefly go over what makes the Hip Flexors so important. They are one of the most used muscle groups in your body, and are responsible for not only leg movement, but assisting upper body movements as well.
The common movements that they are used the most for are:
- Climbing stairs
- Kicking (Swimming, soccer etc.)
Basically anything that requires hip flexion (your leg moving to any angle other than straight down from your torso). There are also other minor movements they assist in, but I’ll address those individually later on as they come up.
Where is it Located?
The first step in learning about anatomy and function is to figure out where your Hip Flexor is located. Take a look at this picture to get a feel for it:
Here is a short description of each of the main components:
- Psoas: About half of humans have a Psoas minor and major muscle, while the other half only have the Psoas major part. If you have both they are right together, and perform largely the same job, so it doesn’t really matter if you’re missing it.
- Iliacus: Right beside the Psoas is the Iliacus muscle (That’s ‘i’ ‘l’). It’s actually connected to a large portion of the Psoas, and put together they are often called the Iliopsoas (named after part of each). The Iliospsoas is the part often mistaken as the whole Hip Flexor, because it is dominantly used when lifting up your leg.
- Tensor Fasciae Latae: Right at the top of the pelvis, the Tensor Fasciae Latae (TFL) connects on one end, and then connects and forms into the IT band on the other end. The muscle is primarily used as a stabilizer during leg extension (when your leg is extended down or behind you). It’s used in walking, but also in things like water skiing and horseback riding when you need to keep your muscles and joint in place.
Minor and Supplementary Muscles
Those three muscles are the most well-known parts, but by no means are they the only ones. Here are 4 supplementary ones that are also important in your everyday life:
- Pectineus: This muscle begins at the Pectin Pubis and connects a bit lower down on the inside of the femur. It is used to pull your leg back towards the middle as needed.
- Piriformis: As you can see in the picture above, the Piriformis inserts right at the top of the femur and the base of the pelvis. It’s main job is to help you rotate your thigh outwards, basically the opposite of the Pectineus.
- Rectus Femoris: The Rectus Femoris is often considered part of both the Hip Flexor and the Quadriceps. It’s a fairly long tissue and attaches down at your kneecap (patella). The main function is to help lift your leg and extend your knee.
- Sartorius: I’ve included a separate picture for the Sartorius below. Fun fact: The Sartorius is the longest muscle in the body. It’s used whenever you move your leg out and rotate at the same time. Like when you kick a soccer ball across your body or sit with one leg on top of your opposite knee.
Why Pain and Injuries are so Common
The Hip Flexor is a commonly injured one, both because of the constant stress on it and because most people have tight muscles from sitting all day. It’s important to stretch them regularly and strengthen them if possible to minimize your risk of a Hip Flexor Injury.
Otherwise, you are now an expert on anatomy in this region, so you should know what is and is not considered part of the Hip Flexor muscle group.