THE GLUTEUS MAXIMUS, THE TENSOR FASCIAE LATAE AND THE ILIO-TIBIAL TRACT

The tensor fasciae latae is a small muscle about 15cm long which is attached to the anterior superior spine and adjacent iliac crest. It is inserted into the ilio-tibial tract.

The ilio-tibial tract is a part of the whole sheath of fascia which encloses the muscles of the thigh. Fascia is a sheet of fibrous tissue enveloping the body beneath the skin. That of the thigh is particularly strong andis called fascia latae. The fibers of the sheath run circularly but at the lateral side of the thigh there is a verystrong band of fibers running longitudinally between the layers of circular bands. This band is called the ilio-tibial tract. This tract is important. It creates a taunt band down the side of the thigh and there is an indentation or furrow caused by it. This is because the tract is attached along it's length to the lateral intermuscular septum, a partition of fascia which is in turn attached along the length of the linea aspera at the posterior of the femur. It's furrow is apparent to varying degrees in most thighs. The tract is inserted into the lateral condyle of the tibia. When the tensor fasciae latae muscle contracts it tightens the tract and helps to straighten (extend) the knee. It is especially well developed in ballet dancers, as are the gluteus medius and gluteus maximus, where the full range of hip movement is used so consistently.

The gluteus maximus is a large rhomboidal shaped muscle. It is attached to the posterior part of the iliac crest, the posterior superior spine, the side and back of the sacrum and the coccyx. The inner quarter of the muscle inserts into the femur. The remaining three-quarters is inserted into the ilio-tibial tract. Through this insertion the gluteus maximus becomes the powerful extensor of the knee.

THE HAMSTRING MUSCLES

These muscles are so named because if their tendons are cut behind the knee, the knee cannot be flexed to allow a step to be taken and a person is therefore powerless and is hamstrung.
These are the three hamstring muscles; biceps femoris which has two heads, semimembranosus and semitendinosus.

They have their origin from the ischial tuberosity of the pelvis, except for the shorter head of the biceps femoris which arises from the back of the femur.

The two heads of the biceps femoris are inserted into the head of the fibula by a common (one) tendon.

Semimembranosus is inserted by a thick tendon into the medial condyle of the tibia. Semitendinosus passes from behind the knee, forward to insert into the medial surface of the tibia. The fleshy bellies of these muscles account for the rich rounded form filling the whole back of the thigh. The tendons can be felt on either side of the back of the knee and when the knee is bent (flexed) they account for the medial and lateral "pillar" forms one sees at the back of the knee joint.

The lower muscle bundles of the trapezius are contracting and appear as definite small columns, either side of the midline of the back. The flat area between them is the aponeurotic tendinous attachment of the trapezius to the spines of the thoracic vertebrae. The middle and upper fleshy parts of the trapezius which are attached to the medial edge of the acromions and the upper borders of the spines of the scapulae are also very obvious mounds as the muscle works to rotate the scapulae. In full rotation of the scapulae, with the arms raised forward and high above the head, the whole lower part of the trapezius is stretched, and would appear quite flattened against the rib cage.

The deltoids are both contracting, lifting the upper arms. The biceps and brachialis muscles are working with them, both to lift the ulna and radius in the lower arms but mainly here to flex the arms against resistance.

The latissimus dorsi muscles are holding the inferior angles of the scapulae against the rib cage. The infraspinatus and the teres major are bulging forms over the upper edges of this muscle.

Note the form of the brachialis. It lies partially under the biceps and is a very powerful muscle. It has a V-shaped attachment on either side of the insertion of the deltoid into the deltoid tuberosity of the humerus, and it is crossing under the biceps to insert into the ulna. Also, on the left arm, the brachioradialis is working with the biceps and brachialis to strongly flex the arm against resistance.

The forms of both inferior angles of the scapulae can be seen. The left one is more apparent on the
edge.

The quadartus lumborum and the spinalis on his right side are stronger contracting forms as he is bending slightly backward as well as to his right.