Last time, we looked at the bony structure of legs, those essential parts of a dancer’s equipment. Today we’ll explore the hip joint, and see how it works, what makes it move, and what you can and can’t do with it. Your hips are beautiful, and fascinating. They can bump and grind, describe incredibly complex rhythms, create wonderful shapes, turn in, turn out, flex, extend and roll — they really are fantastic pieces of you.
Now here’s some technical stuff. The hip is where your thighbone (femur) joins your pelvis, a ball-and-socket joint where the femoral head fits into a shallow, bowl-shaped depression low down on the outer edge of the front of you. This is your hip socket (acetabulum) — named after the Latin word for a vinegar bowl (vinegar featured largely in classical Roman cooking).
Figure 1 below illustrates the bones of your right hip-joint, seen from the front.
Fig. 1: Front view of R. hip bones
Like the ball-and-socket-joint of a windsurfer’s mast, this design allows considerable freedom of movement. The range is not unlimited though, as every dancer knows. To deal with the immense loads they must carry, hips have to be both mobile and stable. The shape and depth of each person’s hip socket determines how far the femoral head can rotate. The neck of the femur is also important, specifically its vertical angle to the shaft of the thigh. If the angle is less than 135°, there will be less freedom when lifting the leg, because the neck of the femur will soon be blocked by the rim of the hip socket. An angle greater than 135° allows the leg to lift higher [1]. Figure 2 shows this angle in the right hip, seen from the front:
Fig. 2: Vertical angle of femoral neck (front view)
There is another bony restriction, which also affects your turnout. Looking down onto the femoral neck from above, you can see a forwards angle of around 10-15° between the neck and the shaft. This small angle of anteversion lets the head sit safely inside the acetabulum even when the leg is turned out. If this anteversion angle is more than 15°, the turning out leg is blocked by the bony edge of the hip socket [1]. Figure 3 below illustrates the angle of anteversion, seen from above, as though through a very small CCTV camera looking downwards from your right ribcage onto your right femoral neck. Even though the foot is pointing straight forward, the neck of the femur is almost impacting the back edge of the hip socket. As the leg turns out further, the femoral neck will move back, but only as far as the acetabular rim — at this point it will be blocked, and no further turnout will be possible.
Fig. 3: Too much anteversion of femoral neck
The smaller the angle of anteversion, the more the head can rotate in the hip socket, and the greater the amount of turnout possible. Turnout will be easier for the lower-anteversion hip in Figure 4, because the head can roll further before reaching its bony limit.
Fig: 4: Normal anteversion of femoral neck (allowing greater turnout)
The femur is firmly attached to the pelvis by several ligaments and a capsule. At the deepest level it is held tightly by the ligamentum teres, running from the acetabulum to a small pit (fovea) on the femoral head. Figure 5 illustrates the attachment point.
Fig. 5: Ligamentum teres attaching to the fovea on the femoral head
This connection of the teres ligament to a single point on the femoral head reminds me of Mr. Chad, a graffiti character popular among the troops in World War II. He’s usually seen peering over a wall, with a single hair on his bald head. You can see him in Figure 6; he looks like this:
Fig. 6: Mr. Chad, with his ligamentum teres hairdo
Around the edge of the acetabulum is a tough ring of cartilage, the labrum (meaning “lip”), strengthened at its lower end by the transverse acetabular ligament. This lip has the effect of making the hip socket deeper, as shown here in Figure 7.
Fig. 7: Labrum and transverse acetabular ligament, deepening the hip socket
The structure is encased in a strong capsule, wrapping all around the bones, from the edge of the acetabulum to the neck of the femur, as shown in Figure 8.
Fig. 8: Capsule wrapping around right hip joint (seen from the front)
Over this are two ligaments at the front of the hip, the iliofemoral ligament (which divides into two bands) and the pubofemoral ligament. These three bands of ligament join up to form the rough shape of a capital “N” on the front of the joint [1]. You can see this in Figure 9.
Fig. 9: “N” formation of ligaments on front of right hip.
At the back of the joint is the ischiofemoral ligament, running like a spiral twist from the lower rear part of the pelvis to the base of the femoral neck, as illustrated in Figure 10.
Fig. 10: Ischiofemoral ligament on the back of the right hip (seen from above and behind)
Depending on the action of the leg (turning in or out, bending or straightening the hip), these ligaments become either taut or slack, so they also play a role in allowing or restricting freedom of hip movement. Typical hip movements might include raising the leg to front, side or back, swinging the leg round in an arc, and closing from any of these positions, as well as turning in or out. Many muscles act directly or indirectly on movement at the hip joint and we can’t deal with them all in one post, so we’ll save most of them for a later entry in this series on dancers’ legs.
One set of muscles we can explore here is the deep outwards rotator muscles [2], which contribute to turnout and turn-in. At the deepest level, there are six of these, all relatively small but very important in their action. They start from various places on your spine or pelvis, and all attach on or near the greater trochanter, that bony protrusion at the top of your thighbone.
The top one, piriformis (Latin for “pear-shaped”) runs diagonally downwards from the front of your lower back at the sacrum and attaches to the top of the greater trochanter.
Extending almost straight across from the outer side of the “sitz”-bones (ischium) to the back of the greater trochanter is the quadratus femoris.
The other four deep outwards rotator muscles are the obturator internus, obturator externus, gemellus superior and gemellus inferior, all starting from various points on lower parts of the pelvis [3] to attach to the inner surface of the greater trochanter. These are the deepest layer of muscle, right next to the skeleton, and are illustrated here in Figure11, showing the left hip as seen from behind.
Fig. 11: Deep rotator muscles of hip
“In order to dance well, nothing is so important as the turning outward of the thighs, and nothing is so natural to man as the contrary position“.
— Jean-Georges Noverre
These six muscles, activating and pulling one after another, cause your thigh to rotate outwards in your hip socket. Other muscles also help in this process, and we’ll look at them in detail later on. The take-home story is, turnout happens in the hip, not the knee, the ankle or the toe joints.
“Ballet is quite unnatural on the joints. My body is just worn. My joints are 10 years older than me“.
— Darcey Bussell
If you are going to stay safe and protect your valuable instrument, turnout action absolutely has to be a hip thing. All right, you can squeeze a few extra degrees from your knees and ankles, but it’s really minimal. Believe me, you do yourself no favours, attempting to disguise limited hip turnout by screwing your feet into exaggerated “toe-to-heel” fifth positions. Fake turnout from floor friction under the sole of your shoe is completely pointless – for one thing, everyone can see it at once from the line of your turned-in leg; also it’s a sure-fire route to long-term injury and painful frustration. It damages your posture, blocks your technique and hurts a lot of joints simultaneously. Really, it’s not worth it.
A much better idea would be to concentrate on turning out safely and correctly. If you can manage this, your hips have every chance of enjoying a long, mobile and untroubled dancing life.
© Jeremy Leslie-Spinks
References
1. Calais-Germain B. (1993, 2007). Anatomy of Movement (revised ed.). Seattle, WA: Eastland Press, Inc.
2. Clippinger K. (2016, 2007). Dance Anatomy and Kinesiology (2nd ed.). Champaing, IL: Human Kinetics.
3. Jarmey C, Myers T. (2006). The Concise Book of the Moving Body. Berkeley, CA: Lotus Publishing, North Atlantic Books.
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