This article covers basic movements of the thigh relative to the pelvis. It includes
Creating Space and Stabilizing the Hip Joint
Two very basic movements for the hips include creating space and stabilizing.
The first movement feels like pulling the thigh bone away from the hip socket or pushing the pelvis away from the thigh bone.
The second movement feels like you are sucking the thigh bone into the hip socket (or sucking the pelvis towards the thigh bone.)
The first movement, creating space, uses the gemellus superior, gemellus inferior, obturator internus and externus to create the space. These muscles generally externally rotate the thigh with respect to the pelvis. To balance this action, the tensor fascae latae, gluteus minimus and/or the long head of the adductor magnus may also activate. These muscles can be used to cause internal rotation.
The gemellus and obturator muscles are all close to the hip joint, near the junction of where the thigh joins the pelvis. To try to sense or feel these muscles we can put our awareness in the region of the groins. More specifically we can put our awareness in the regions of our pubic bone and sitting bones and the ischiopuboramus which spans the two.
The obturator internus and the two gemelus leave the pelvis just above the sitting bones and reach “upwards” and “forwards” to connect to the back of the top of the thigh bone.
The obturator externus reaches back from the pubic bone, passes underneath the neck of the thigh bone to attach to the back of the thigh bone.
The tensor fascae latae and gluteus minimus are both at the side of the pelvis between the head of the thigh bone and the top crest of the pelvis while the adductor magnus is the largest of the adductors, located at the inner thigh.
Sucking the hip joint may be caused by contracting the quadratus femoris, pectineus, and piriformis. These muscles also lay within the region of the groins.
Quadratus femoris and piriformis have similiar lines of pull, reaching down from a point just above the sitting bones to the back of the thigh bone.
The piriformis attaches to the front of the sacrum and so with “sucking” you may feel a slight pulling forwards of the sacrum.
The pectineus reaches down and back from the region of the pubic bone to the top of the inner thigh.
These muscles chiefly act in external rotation so that again the internal rotators may activate to counter this tendency.
In prone backbends like locust, or in poses like cat where we reach one leg back, we could try creating space in the hip joint to give the leg room to move relative to the pelvis.
In forward bends, whether standing or sitting, we might find that creating space in the hip joint gives us room to tilt the pelvis forwards relative to the thigh bones.
Standing on one leg and moving the pelvis relative to that leg we might want to try creating space in the standing leg hip joint.
Standing on one leg and keeping the pelvis still we might want to try to stabilize the standing leg hip joint.
There may be situations where we try to do both actions at once, first creating space and then stabilizing the joint or stabilizing the joint and then trying to create space.
Hips, Opening the Back or Front
Opening the back of the hips is the same as tilting the pelvis forwards relative to the thighs or swinging the thighs forwards and up towards the front of the body.
The technical name is flexion.
Extension or opening the front of the hips corresponds to tilting the pelvis backwards relative to the legs or swinging the legs back relative to the pelvis.
Hip flexion, tilting the pelvis forwards or opening the back of the hip can be done by the psoas and illiacus. These both attach to the top of the inner thigh to a point called the lesser trochanter which actually is at the back of the top of the thigh. The illiacus attaches to the inside edge of the blade of the pelvis while the psoas attaches to the front of the lumbar spine.
If we stabilize the lower back using the abdominals and erector spinae then the pelvis and ribcage act as one unit. We can then focus on tilting the pelvis and lumbar spine forwards towards the thigh or thighs using the psoas and illiacus.
The feeling is as if pulling the lumbar spine and pelvis towards the inner thighs but rather than bending the spine we are rotating it along with the pelvis around the axis of the hip joint.
If when laying on our back we move the thighs towards the front of the body then the feeling is of squeezing the top of the inner thighs towards the belly.
The tensor fascae latae can also be used to open the back of the hip joint. The belly of this muscle is near the side of the hip joint towards the front but it acts via the fascea latae on the fibula, the small outer bone of the lower leg as well as the tibia.
If the illiacus pulls inwards on the blades of the pelvis when active, this muscle pulls outwards.
The pectineus, adductor brevis and adductor longus can all be used to open the back of the hip (red, green and yellow respectively).
These muscles all attach to the inner thigh from near the top of the thigh bone to about half way down. They attach to the pelvis near or at the pubic bone.
These muscles also tend to externally rotate the thigh when active and so this has to be countered by an internal rotation. The tensor fascea latae may help in providing that internal rotation.
The rectus femoris can also be used to open the back of the hip. Like the Tensor Fascae Latae is also crosses the hip and the knee.
It attaches via the knee cap to the front of the tibia, the larger of the two lower leg bones. It also attaches to the front of the pelvis near the top at each side.
This muscle has more contractive room when the knee is bent. Trying to use it when the knee is straight may cause cramping. It may be useful in kicking actions to flick the knee straight at the thigh is swung forwards.
When holding a forward bend it may be indesirable to use this muscle.
When lifting a leg (perhaps while sitting or while standing or while balanced on the pelvis) it may be easier to use the psoas and illiacus to open the back of the hip if we start with the leg open out to the side. These muscles then have more room to contract and it may be easier to keep them contracted as we swing the leg so that it is straight ahead.
For hip extension, opening the front of the hip, we can use the adductor magnus. This muscle attaches between the sitting bone and the inner thigh bone just above the and behind the knee joint.
In belly down backbends this muscle can be used to lift the thigh bone. It tends to rotate the thigh internally and in a belly down position the weight of the leg itself when lifted accentuates this tendency.
The gluteus maximus can also be used to open the front of the hip however this muscle can also get in the way because it is so bulky. It is similir to someone moving a couch up a narrow stairwell and becoming jammed between the couch and the wall.
This muscle is probably more appropriate for swinging the leg back from a forwards position.
Piriformis, quadratus femoris, obturator internus, gemellus superior and gemellus inferior can also be used to open the front of the hip. However they all tend to externally rotate the thigh and so possibly this tendency can be countered by using the internal rotatores.
Internally and Externally Rotating the Hip
Internally rotating the hip generally refers to rolling the thigh inwards around it’s long axis. This means the front of the thigh bone moves inwards and the back of the thigh bone moves outwards.
If one thigh is kept still and the pelvis moves relative to that thigh then internal rotation causes the opposite side of the pelvis to move forwards. External rotation does the opposite. If a thigh is kept stable then the opposite side of the hip moves backwards. If the pelvis is the reference then external rotation of the thigh causes the front of the thigh to move outwards.
With both feet on the ground we can turn the pelvis to the right. This causes internal rotation of the left hip and external rotation of the right hip.
Rotation of the hip can occur by virtue of the position the feet are in while in contact with the floor or some solid surface. In such a case the legs are passively rotated. No muscle needs to be active to cause this action.
Internal rotation can be performed by the gluteus minimus and the adductor magnus. It can also be assisted by the tensor fascae latea.
External rotation can be performed by pectineus, adductor brevis, adductor longus. These muscles all lay within the inner thigh compartment. It can also be caused by the obturator internus, gemellus superior and inferior, piriformis, quadratus femoris. These muscles are closer to the pelvis and can be thought of as being in the groins.
Psoas and illiacus can also be used to cause external rotation. When using these muscles to externally rotate a lifted leg the weight of the leg itself can be used to assist in external rotation.
Opening the inside or outside of the Hip
In a standing position we can think of using both legs to push the pelvis to one side. If we push the pelvis to the left then we open the inside of the left hip and the outside of the right hip.
Laying on our left side we could lift the right leg and thus open the inside of the right hip. In general, moving one leg out to the side we open the inside of the hip of that leg. Moving the leg inwards (assuming the other leg is not in the way) then we open the outside of that hip.
In a standing position like warrior 2 where one knee is bent and the other is straight, we can use the outer thigh of the bent knee to turn the pelvis to the side. In this case also we can say that we are opening the inside of the hip.
To open the inside of the hip we can use the glute maximus, the tensor fascae latae, the glute medius and glute minimus.
We can also open the inside of the hip passively in an action or position like side splits where we allow the legs to slide away from each other.
To open the outside of the hip we can use the pectineus, adductor brevis, adductor longus, adductor magnus. We may also be able to use the deeper hip muscles but their contribution may be slight.
Psoas and illiacus can also be used to open the outer hip.
Special Cases for External Rotation
In a posture like pigeon where the thigh is forwards and externally rotated, the outer hip tends to be stretched which means that possible we can use some part of the inner thigh to help open the outer hip. From a standing position, we can use the glute maximus and quadratus femoris to externally rotate the thigh. However in a position like pigeon where the thigh is forwards and externally rotated, it may be that this position can be used to stretch these two muscles.
We may also be stretching the tensor fascae latae which normally does internally rotate the thigh.
In a posture like butterfly with the feet close to the pelvis, the inner thighs tend to be stretched. With the feet positioned further away from the pelvis the outer thighs tend to be stretched.
At some point between these two extremes we move from stretching the outer thigh to stretching the inner and from using the inner thigh to using the outer.