294 Dance Anatomy and Kinesiology
influenced by anatomical and biomechanical fac-
tors such as the law of valgus. The law of valgus and
related Q angle give rise to a tendency for lateral
tracking of the patella that can be exaggerated by
alignment abnormalities, inadequate quadriceps
strength, or twisting of the tibia, such as occurswith forced turnout. To encourage optimal patello-
femoral mechanics and lessen the risk of injury, it is
important that dancers develop adequate quadriceps
strength and balanced muscle activation patterns
and that they focus on correct alignment between
the hip, knee, and foot.Study Questions and Applications
- Locate the following bony landmarks on a human skeleton: (a) medial femoral condyle and
epicondyle, (b) lateral femoral condyle and epicondyle, (c) tibial plateau, (d) tibial tuberos-
ity, and (e) patella. - Draw the following muscles on a skeletal chart, and use an arrow to indicate the line of pull
of each muscle. Then, next to each muscle, list its actions: (a) rectus femoris, (b) vastus late-
ralis, (c) vastus intermedius, (d) vastus medialis, (e) biceps femoris, (f) semitendinosus, (g)
semimembranosus, and (h) popliteus. - Locate the following muscles on your partner, and have your partner perform actions that
these muscles produce while you palpate their contraction: (a) quadriceps femoris, (b) biceps
femoris, (c) semitendinosus, and (d) semimembranosus. - Sitting in a chair, resist knee flexion by putting your left foot behind your right foot while
pulling back with the right leg (resisted isometric knee flexion). Place your right hand under
the right side of the back of the thigh and your left hand under the left side of the back of the
thigh. Palpate the hamstrings as you pull back with (1) the tibia and foot externally rotated,
(2) parallel, and (3) internally rotated relative to the femur. Explain the differences you feel
in muscle contraction during these conditions. - Demonstrate two exercises for strengthening and two exercises for stretching the following
muscles: (a) quadriceps femoris, (b) hamstrings. - Delineate differences in exercise design required in order to focus on the rectus femoris
versus the vasti muscles for both strengthening and stretching exercises. - Mark the midpoint of your patella and tibial tuberosity with a pen or adhesive dot. Then perform
a standing first-position demi-plié, and note the change in relationship between the dots on
the patella and tibial tuberosity when the knee extends on the up-phase of the movement.
Explain how this relates to the locking mechanism of the knee. - Use a marking pen to draw the Q angle on your knee (or your lab partner’s knee) accord-
ing to the directions provided earlier in this chapter. Then, sitting with both legs extended
forward, note any lateral motion of the patella as you perform a quad set. Compare your Q
angle with that of three other dancers. Describe how the law of valgus relates to this lateral
tracking of the patella, and list two other alignment deviations that will tend to enhance this
tendency for lateral tracking. - Place one hand on the front of the thigh about 6 inches (15 centimeters) above the patella
and the other behind and above the knee on the hamstring muscles. Palpate these muscles
while performing a demi-plié in first position (parallel), and note that contraction is present
in both muscle groups. Explain how this can be occurring even though they have antagonistic
functions at the hip and knee. - Perform an analysis of a back attitude, accounting for the joint movements, muscles groups,
and sample muscles of the hip and knee of the gesture leg. Then, describe how active and
passive insufficiency could be operative.
(continued)