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here, in short :
o SKILLS
the JOINT segments of the LEG
Where should the knee point in standing postures like Warrior (Virabhadrasana) Or in Squat (Malasana)? Where should the feet point? Can every one do Lotus (Padmasana) safely? Is there always a risk if someone hyperextends their knees?
HIP joint
The hip joint is the meeting of the ball at the top of the FEMUR (femoral head) with either side of the PELVIS (acetabulum).
The femur (thigh bone) is the longest and strongest bone in the body. The femur has many twists and turns which help determine the ultimate potential range of hip joint motion for a variety of movements. The femoral head (ball) is at the end of the short section of bone called the femoral neck. A large bump juts outward from the top of the femur, next to the femoral neck. This bump, called the greater trochanter, can be felt along the side of your hip.
Variations of the femur :
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Femoral torsion (twisting along the shaft of femur): Every long bone in our body has a slight rotation to it. In the femur we call this twisting femoral anteversion. If there is only a small twist, no twist or a negative amount of twist it is called femoral retroversion. In general, and all other things being equal, people with less torsion will find it easier to externally rotate their femur in the hip socket (Lotus - Padmasana) and those with higher will find it harder to externally rotate, but easier to internally rotate (Eagle - Garudasana) The degree of anteversion / retroversion will also contribute to the natural positioning of the feet.
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Femoral neck shaft angle (turn occurring between the shaft & the neck of the femur) : Femur neck angles can vary greatly, the wider the angle the greater potential for abduction at the hip socket.
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Length of neck : Neck length is a factor in the range of motion available before the greater trochanter squeezes against the side of the pelvis. The longer the neck, the greater the range of motion possible.
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Size of greater trochanter : The larger the prominence of the greater trochanter, the sooner compression will be reached in abduction and the lower the greater trochanter, the more room you’ll have before compression occurs
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The femoral head fits into a round socket on the side of the pelvis. This socket is called the acetabulum. The key variations of the acetabulum that can affect our mobility and range of motion include:
- Angles of the acetabulum relative to the 3 planes of the body
- The shape of the acetabulum (including size,roundness, depth)
- The verticality of the anterior pelvic plane.
Acetabular depth : If the acetabulum is shallow, a greater range of motion in the hip socket is possible, however it is subject to more stress as the amount of surface that supports the weight of the body is smaller.
The APP is formed by points of the ASIS and pubic tubercle. It was long believed everybody had a perfectly vertical APP. When the ASIS juts forward = pelvis anteversion, backwards is called retroversion of the pelvis. This plane is not a reliable indicator of wether or not the pelvis is tucked. The orientation of the pelvis by the slope of the sacrum is better.
The bony ridge that forms the acetabulum is covered by a cartilage lip called the LABRUM, which essentially extends the acetabulum and adds stability to the joint. It is also associated with managing stress coming into the joint as well as helping to seal the joint. The extra depth to the acetabulum created by the labrum can also restrict movement and sometimes if the labrum is too thick, it pinches in, causing impingement problems. It can be injured and cause pain and clicking in the hip.
The femur is bound to the pelvis by LIGAMENTS surrounding and inside the synovial joint capsule of the hip joint. They are particularly strong and dense, reinforcing the joint in a variety of directions. These ligaments are the main source of stability for the hip. They help hold the hip in place. As in many places in the body there is debate as to how much each ligament restricts movement in a particular direction.
A long tendon band runs alongside the femur from the hip to the knee. This is the iliotibial band. It gives a connecting point for several hip muscles. A tight IT BAND can cause hip and knee problems.
The potential range of motion for the hip is tremendous considering its location, the amount of weight it supports and the force it generates. The hip joint is referred to as a ball-and-socket joint that allows the ball of the femur to spin (in flexion & extension), roll and a bit of sliding (abduction, adduction, external/internal rotation) in the cup of the hip socket.
Just because a joint has the potential to move in all these directions doesn’t mean that it does.
Muscles causing and restricting hip movement varies depending on the orientation of the thigh to the pelvis. From an anatomical position :
Compressive restriction to movement can occur in 4 areas around or in the hip joint (assuming the tensile resistances of fascia, muscles, ligaments and joint capsules are no longer inhibiting the movement needed to reach compression) :
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Soft compression - abdomen or chest hitting the thighs
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Medium compression - tissues caught between the front of the pelvis (ASIS) and the thigh (bone hitting flesh)
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Medium compression - tissues caught between the greater trochanter and the side of the pelvis (ilium) which results in 2 bones trapping flesh between them.
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Hard compression - neck of the femur impinges upon the labrum of the acetabulum (bone on cartilage compression)
The hips see a lot of variation in bone shape making the determination of hard compression most challenging. There are a great deal of variation in the angles that come together at the hip and both sides are likely to be different.
MENISCI - Due to the shape of the knobbly ends of the femur, and the relatively flat surface of the top of the tibia, between these 2 bones are the meniscus : The menisci are 2 (lateral and medial) semi circular pieces of cartilage. They create a deeper cup, for greater stability, they also play as a shock absorber and help with the knees functional movements, where they move and distort in shape. Meniscus tears are common in yoga, wether originally from the asana practice or exacerbated by it. Poses such as Lotus (Padmasana) where forced rotation at the hip can transfer stress to the knee when the foot is held in place, by the floor or another part of the body.
Unlike most joints, there is no bony stop to limit movement; instead, ligaments, tendons, fascia and muscles combine to resist hypermobility.
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The Anterior Cruciate Ligament (ACL). The ACL connects the tibia to the femur and functions to prevent the tibia from sliding forward on the femur. The ACL is commonly injured and rarely in isolation.
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The Posterior Cruciate Ligament (PCL). The PCL also connects the tibia to the femur. It functions to prevent the tibia from sliding backward on the femur. It can become injured in hyperextension.
These strong ligaments are the primary stabilisers of the knee. They prevent the femur from slipping off the stationary tibia. Cruciate means ‘crossing’ this arrangement causes the two cruciate ligaments to wrap around each other when the tibia is internally rotated under the femur. When the tibia externally rotates under the femur the two cruciate ligaments move away from each other allowing more range of movement.
The strap like collateral ligaments (medial MCL and lateral LCL) connect the femur to the tibia. The collateral ligaments help to prevent twisting and side movements of the tibia under the femur when the leg is fully extended. When the knee flexes the collateral ligaments are slightly lax allowing for postures like Lotus (Padmasana)
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The Lateral Collateral Ligament (LCL). The LCL, which is also known as the fibular collateral ligament, is located on the outside (lateral side) of the knee. It connects the outside, bottom edge of the femur to the outside, top edge of the fibula. The LCL helps stabilise the knee joint by limiting outward (varus) force across the knee.
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The Medial Collateral Ligament (MCL). The MCL is located on the inside (medial side) of the knee, connecting the inside, bottom edge of the femur with the inside, top edge of the tibia. The MCL helps to stabilise the knee by limiting inward (valgus) force across the knee. The MCL works with the LCL to prevent unwanted side-to-side motion. The MCL is the most commonly injured knee ligament.
KNEE joint
The femur, tibia & fibula, meet the patella to create the largest joint in the body - the knee-joint segment.
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The knee must be strong, bearing a lot of body weight.
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The knee must be flexible, enough to deal with the
adaptations of the foot and the hip.
Technically, the knee is made up of 4 separate joints:
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the patella & the femur
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the fibula & the tibia
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the medial condyle of the femur with the tibia
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the lateral condyle (expansion) of the femur with the tibia
THE TIBIA (shin bone) is the primary weight bearing bone of the lower leg, The secondary being the FIBULA.
THE FEMUR (thigh bone) is both the longest and strongest bone in the human body.
THE PATELLA (kneecap). The patella sits at the anterior-most (front) of the knee joint.
The knee supports the weight of the body so there is a lot of compression of the femur onto the tibia & of the patella onto the end of the femur. These areas of compression generally do not limit range of motion. The stress of doing too much or not enough can lead to pathology.