Quadriceps
The quadriceps muscles are the four functionally linked front-of-thigh group. Included in the quadriceps group description is the sartorius muscle, which is the longest muscle in the body. It is not actually one of the quadriceps but extends from the outside of the hip bone (ilium) just below the waist diagonally across the front of the thigh over the inner side of the knee and is attached to the top of the inner side of the shin-bone (tibia). Rectus femoris is the muscle attached at two points of the pelvis and runs straight down to the knee cap. It runs underneath the sartorius and over the top of the other quadriceps muscles which are closely attached to the top of the thigh bone (greater trochanter - the bone felt at the hip). The picture (left) is of the right leg viewed from the front. One of them extends over the inner side of the thigh (vastus medialis) and the others, vastus intermedius and vastus lateralis, spread over the outer side. The four muscles in this group join up at the knee-cap which is a free-floating knob of bone actually formed within the muscle fibres and form a single tendon - the patellar tendon. This extends from the upper pointed end of the knee-cap to the tibial tubercle at the top of the front of the shin-bone.
When the thigh muscles are tensed by straightening the knee the quads clearly stand out. The vastus medialis bulges out just above the knee on the inner side while the limits of the vastus lateralis at the outer side are defined by the iliotibial tract, which forms a straight indentation down the side of the thigh dividing vastus lateralis from the hamstrings at the back of the thigh. While sitting and lifting your leg from the hip the top of sartorius can be felt tightening just below the waist.
The quads group straightens the knee against gravity or a resistance and controls the opposite movement of flexion of the knee when this is done in the direction of gravity The speed at which squats are performed from a standing position is controlled by the quads paying out preventing gravity pushing you down. Straightening up is done by the quads contracting, shortening the muscles. Rectus femoris and sartorius also help to bend the hip when you bring the thigh or trunk forward like in the sitting up motion from lying down on your back. Sartorius is important and has complex functions. It crosses two joints (the hip and knee). It turns the thigh bone at the hip and pulls the leg inwards towards the other leg. Running up hill or kicking a football with the inside of the boot would not be possible without it. The quads also work hard when running up hill but harder running down, controlling knee movement at speed. The quads also act as postural muscles helping to stabilise you when standing upright against the influence of gravity.
To prove to yourself that tension is always present but sometimes almost unnoticeable, stand on one leg and feel around its entire upper thigh area between the knee and groin. There is considerable tension especially in the hamstrings. The effects of gravity weighing down the body upon the other leg are essentially absent and this means that no muscular action is required to prevent the knee from buckling. This leg is quite relaxed all over. Now, while feeling around this leg, lower it to the ground and transfer your weight over it. The muscles harden as support for the body occurs. Gravity effects are attempting to buckle your knee, after all your entire body weight is now being supported - how heavy are you?
But you can hardly feel the muscles under tension if you do not touch them. This is even less obvious when you are standing in a comfortably balanced way on both legs. We all get used to the feel of muscle action when we are not seemingly doing anything and don't notice it. This is precisely the reason it is very hard to relax completely even when resting in the prone position. You have to consciously think about each area of your body to actually relax muscles completely. Classically, neck tension is quite considerable for supporting the head even when attempting to sleep and it is not difficult to appreciate why headaches occur even though you cannot always feel the tension.
When the thigh muscles are tensed by straightening the knee the quads clearly stand out. The vastus medialis bulges out just above the knee on the inner side while the limits of the vastus lateralis at the outer side are defined by the iliotibial tract, which forms a straight indentation down the side of the thigh dividing vastus lateralis from the hamstrings at the back of the thigh. While sitting and lifting your leg from the hip the top of sartorius can be felt tightening just below the waist.
The quads group straightens the knee against gravity or a resistance and controls the opposite movement of flexion of the knee when this is done in the direction of gravity The speed at which squats are performed from a standing position is controlled by the quads paying out preventing gravity pushing you down. Straightening up is done by the quads contracting, shortening the muscles. Rectus femoris and sartorius also help to bend the hip when you bring the thigh or trunk forward like in the sitting up motion from lying down on your back. Sartorius is important and has complex functions. It crosses two joints (the hip and knee). It turns the thigh bone at the hip and pulls the leg inwards towards the other leg. Running up hill or kicking a football with the inside of the boot would not be possible without it. The quads also work hard when running up hill but harder running down, controlling knee movement at speed. The quads also act as postural muscles helping to stabilise you when standing upright against the influence of gravity.
To prove to yourself that tension is always present but sometimes almost unnoticeable, stand on one leg and feel around its entire upper thigh area between the knee and groin. There is considerable tension especially in the hamstrings. The effects of gravity weighing down the body upon the other leg are essentially absent and this means that no muscular action is required to prevent the knee from buckling. This leg is quite relaxed all over. Now, while feeling around this leg, lower it to the ground and transfer your weight over it. The muscles harden as support for the body occurs. Gravity effects are attempting to buckle your knee, after all your entire body weight is now being supported - how heavy are you?
But you can hardly feel the muscles under tension if you do not touch them. This is even less obvious when you are standing in a comfortably balanced way on both legs. We all get used to the feel of muscle action when we are not seemingly doing anything and don't notice it. This is precisely the reason it is very hard to relax completely even when resting in the prone position. You have to consciously think about each area of your body to actually relax muscles completely. Classically, neck tension is quite considerable for supporting the head even when attempting to sleep and it is not difficult to appreciate why headaches occur even though you cannot always feel the tension.
posted by Louis Brothnias @ 12:19 PM
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