The size of the pelvis is due to its position as the mechanical axis of the body; it is the fulcrum for the muscles of the trunk and legs, and is large in proportion. Its mass inclines a little forward, and is somewhat square as compared with the trunk above.
At the sides the ridge is called the iliac crest. It is the fulcrum for the lateral muscles and flares out widely for that purpose; rather more widely in front than behind.
Above the rim is a roll of muscle belonging to the abdominal wall: immediately below it a groove or depression, made by the sag of the hip muscles, obliterated when these are contracted in action.
So great are the changes in surface form of the muscles in different positions of the hip that the iliac crest remains as the one stable landmark. It is a curve, but being beveled backward, it presents to the side view two lines and almost an angle between them at the top.
The posterior line is marked by two dimples where it joins the sacrum, and the line continues downward into the fold of the buttocks. From this whole line the gluteus maximus muscle passes down and forward, to just below the head of the thigh bone, making the mass of the buttocks and hip.
Just in front of this, from the top of the crest, descends the gluteus medius muscle, forming a wedge whose apex is at the head of the thigh bone. Between these two muscles is the dimple of the thigh.
Only part of the medius is superficial; its front portion is overlaid by the tensor fasci;e femoris muscle, which rises from the edge of the front line of the crest and descends to form with the gluteus maximus the wedge filled in by the medius. The two fasten to the dense plate of fascia that guards the outside of the thigh (ilio-tibial band). This muscle is always prominent and changes its appearance greatly in different positions of the hip, forming a U-shaped wrinkle when the thigh is complete-ly flexed.
On the front end of the crest is a small knoh, from which descends the sartorius (tailor's) muscle, longest in the body. It forms a graceful curve as it lies in the groove of the inner side of the thigh, passing to under the knee.
From just below the knob, overlaid therefore by the sartorius, descends the rectus femoris muscle, straight to the knee cap.
From the knob, the line continues down and in to the symphysis, marking the boundary between abdomen and thigh.
The Pelvis and Hip.
1 Tensor vaginae femoris.
3 Rectus femoris.
4 Gluteus medius.
5 Gluteus maximus.
From ilium, outer surface, to femur, greater trochanter.
Abducts and rotates inward thigh.
From crest of ilium, rear portion, sacrum and coccyx to femur.
Extends, rotates and turns out thigh.
The thigh extends from the pelvis to the knee, and the leg from the knee to the foot.
The longest and strongest bone of the body is the femur (thigh bone). It is joined to the bones of the pelvis at the hip socket by a long neck, which carries the shaft itself out beyond the widest part of the crest. From there the femora (thigh bones) converge as they approach the knees, bringing the knee under the hip socket. At the knee, the femur rests on the tibia (shin bone), the main bone of the leg, and makes a hinge joint. The tibia descends to form the inner ankle. Beside it, not reaching quite to the knee, is the fibula, the second bone of the leg, which descends to form the outer ankle. It is located on the outside, and is attached to the tibia at the top and bottom. These two bones are almost parallel. Above the juncture of the femur and tibia lies the patella (knee cap). This is a small bone almost triangular in shape. It is flat on its under side, and convex on the surface.
The great trochanter of the femur is the upper tip of the shaft which reaches up slightly beyond where the neck joins.
The lower portion of the femur widens to form two great hinge processes, known as tuberosities. They are on the outer and inner sides, and they are both visible.