Anatomy 101: Hip Flexion
Last month we touched upon the hip and how it’s function during the squat is affected.
This month, we are going to dive into the actual structure of the hip and how it is made up and the different muscle groups create movement and stability through that joint. There is a lot to cover as there are approximately a dozen muscle groups that do this so let’s get to it then.
Section I: Structure
As I mentioned last month the structure of the hip is composed of four general bone structures. They are:
- The proximal aspect of the femur,
- The pelvic bone,
- The Sacrum, and
- The lumbar spine
Each of these four pieces have some other important structures that we are going to look at in a bit but before we move on we need to clear the air about a very important fact about men and women and how they are structurally different.
Women have a wider hip span than men. This wider hip span allows them to give birth to the next generation. This wider hip span also does some other very interesting things such as create a longer attachments points so the muscles around these joints now must be bigger and stronger. The illustration below shows what I mean.
As you can see the female hip is much wider, structurally, than a male’s hip. This indicates that the muscles that attach to the pelvic bones are bigger and therefore much stronger than a male. Not only that but the head of the femur also sits differently inside the socket of the pelvis. So, as much as we try to be equal, we are very different on a structural aspect.
Now getting back to the parts of the sections of the hips. We are going to start with the architecture of each structure and see what they are made up of.
First, we are going to start with the femur. We are most interested with the proximal aspect (closest to the head) of the femur. This is made up of five distinct landmarks. They are:
- Greater Trochanter
- Lesser Trochanter, and
- Intertrochanteric Line
The Head of the femur is a ball of a ball and socket joint. It allows the femur 360° in all three directions (Horizontal plane, vertical plane and sagittal plane)
It sits inside the socket of the pelvis and is encapsulated by the acetabulum labrum of the hip. This allows the lower this kind of freedom of movement and distribution of stress from the upper body to the lower body.
The Neck of the femur is a construction that not only connects the head to the body of the femur but also allows the clearance needed for the freedom of movement in the lower body. This is a common site for fracture as it is a point of weakness. -innerbody.com
The greater trochanter is a bony prominence that protrudes laterally from the body of the femur it is more for attaching tendons to and is a very strong point of the femur. It can be felt placing your thumbs on your bony part of your hip, run your down your hip and your middle finger should feel the body prominence that is the greater trochanter.
The lesser trochanter really doesn’t play that huge of a role other than it some of the adductors connect to this little prominence.
The intertrochanteric line is yet another landmark that is quite important as to it plays a crucial role in weight bearing through the skeletal system. Problems can arise in the from of fractures as this is a very weak point in the lower body and the amount of forces that go through this landmark are immense. -Wikipedia
So that pretty much sums up the first part of our long trek back up to the head. The next part (the pelvis) won’t be as bad I promise
The pelvis is compromised of two separate bones (the left and the right) these two bones are connected by the sacrum (we will look at this in a bit) and the cartilage at the pubic symphysis
Each pelvic bone is broken down into three general areas. They are:
- The Ilium is the upper most part of the hip bone and consists of two general parts the body and the wing. The body forms part of the acetabulum where the head of the femur sits. The wing is the large expanded portion of the upper pelvis it has separate areas of importance, the external and an internal surface, a crest, and two borders—an anterior and a posterior. -Wikipedia
- The Pubis consists of two areas the superior ramus and the inferior ramus. The superior ramus creates one-fifth of the acetabulum and the inferior ramus blends with the ischium to form an area known as ischiopubic ramus. -MedFriendly
- The Ischium is made up of three parts the body which creates a little more than two-fifths of the acetabulum, the superior ramus which gives origins to three major muscles quadratus femoris, adductor magnus (external surface) and the hamstrings (posterior surface), and the inferior ramus which is a flattened part of the ischium that ascends from the superior ramus, and joins the inferior ramus of the pubis. -Wikipedia
The sacrum is really considered part of the pelvis but I have separated it because it really needs it’s own section as its complexity is on its own a special case.
The sacrum is 5 separate bones (S1-S5) that are fused together between the ages of 18-30. It also has the coccyx (tail bone) at the very end of the S5 bone. It has three surfaces – a pelvic, dorsal and a lateral surface. The bas of the sacrum is directed upward and forward, now without getting to clinical let’s just sum up that the sacrum is a vital part of the spine as it is the termination point of the spine and still houses and sorts the distribution of the nervous system. It also has some important landmarks for muscles, fascia, ligaments, and tendons. -Wikipedia
Now the lumbar spine I will not get into here as I need another 1,000 words or so to describe what is going on there (that is coming in another month). I think for now that will be enough as I think I have lost most of you.
Section II: Muscles
This is going to be a very short section as I have already gone through all the muscles needed and required to preform hip flexion in last months Squat Report so please go and give that a read through.
Some final words of this, I know it’s a lot but this is just one of those parts of the body that is just so complex that it just needs a lot of explaining.