The Pelvic Girdle and Hip Joint 187the relative activation of the relevant muscle group.
For example, performing a turned-out arabesque
would theoretically recruit more of the biceps femo-
ris than the medial hamstrings, due to the secondary
functions of the medial hamstrings of hip internal
rotation. Additional electromyographic (EMG)
investigation of basic dance vocabulary in parallel
versus turned-out positions would provide valuable
insights into relative muscle activation.Hip Flexion
Hip flexion decreases the angle between the anterior
surfaces of the articulating bones. The iliopsoas,
rectus femoris, and sartorius are assisted by other
hip flexors (table 4.4) to perform their customary
action when contracting concentrically against grav-
ity or resistance to lift the femur to the front in kneeto chest, front leg raise, and front développé (table
4.5, A-C, pp. 213-214), or in swinging the leg forward
in walking, running, kicking, and many sports. In
dance, this type of hip flexion is used whenever the
leg is moved to the front such as in a tendu, dégagé,
front attitude, front battement, or the front leg of a
jump (sissone) as seen in figure 4.23.
The hip flexors are used in their reversal of custom-
ary action when they contract concentrically to bring
the pelvis or trunk, or both, forward in an anterior
pelvic tilt, a sit-up (see figure 2.8 on p. 43), and floor
work such as a contraction series in modern or chest
lifts in jazz dance. An example of the combined
use of movement of the legs and torso is shown in
figure 4.24, in which the dancer raises from a flat
position on the ground by flexing at the hip and
bringing both one thigh and the torso simultaneously
together. In contrast to a classic curl-up, the spine isTABLE 4.4 Fundamental Hip Movements and the Muscles That Can Produce Them
Hip joint movement Primary muscles Secondary muscles
Flexion Iliopsoas
Rectus femoris
SartoriusTensor fasciae latae
Adductor longus and brevis (early flexion)
Gracilis
Pectineus
Extension Gluteus maximus
Hamstring muscles:
Biceps femoris
Semitendinosus
SemimembranosusAdductor magnus (lower fibers)Abduction Gluteus medius
Gluteus minimusTensor fasciae latae
Sartorius
Iliopsoas (upper ranges of abduction)
Adduction Adductor longus
Adductor brevis
Adductor magnus
GracilisPectineusExternal rotation Deep outward rotators:
Obturator externus
Obturator internus
Piriformis
Quadratus femoris
Gemellus superior
Gemellus inferior
Gluteus maximusSartorius
Biceps femorisInternal rotation Gluteus medius (anterior fibers)
Gluteus minimus (anterior fibers)Tensor fasciae latae
Semimembranosus
Semitendinosus