164 Dance Anatomy and Kinesiology
Description and Functions of Individual Hip Muscles
Twenty-two muscles cross the hip joint. However,
despite the large number of muscles involved, they
are arranged in a logical way that makes remember-
ing their actions easier—the anterior group are all
hip flexors, the posterior group are generally hip
extensors (except for the deep outward rotators), the
lateral group are all hip abductors, and the medial
group are all hip adductors. However, although their
primary actions are the same, members of these
groups may have different secondary actions.
In terms of deducing primary and secondary
actions, it is important to keep in mind that since the
hip joint has three degrees of freedom of motion,
many hip muscles will exert action about all three
axes simultaneously. However, one or two actions
will often predominate, due to better leverage of
the muscle with respect to that axis. For example,
the actions of hip flexion and hip adduction pre-
dominate with the pectineus, and its contribution to
rotation is generally not considered very significant.
In addition, some muscles are extensive enough that
different portions may have different relationships to
a given axis and hence may be capable of a different
action. For example, many texts list the upper fibers
of the adductor magnus as a flexor and the lower
fibers as an extensor. Lastly, remember that as dis-
cussed in chapter 2, the action of a muscle may differ
with changes in the joint angle due to the shift in
the line of pull relative to the axis. For example, the
adductor longus aids with early flexion, but its effec-
tiveness decreases continuously until it no longer aids
with flexion; and after approximately 70° it actuallyproduces hip extension. Due to this complexity, it
is not surprising that many of the secondary actions
of hip muscles are still under debate. Many of the
controversial secondary actions have been purposely
excluded from this text. (See Individual Muscles of
the Hip, pp. 165-177.)Alignment and Common Deviations of the Hip Region
Alignment of the bony segments in the hip region
is important in itself and also influences the bony
segments above and below the pelvis and hip joint.
For example, alignment of the pelvis will influence
the spine above and the knee, ankle, and foot below.
Three alignment considerations in the hip region
that are particularly important are pelvic inclina-
tions or tilts, the angle of femoral inclination, and
the angle of femoral torsion.Pelvic Alignment and Movements
The position of the pelvis can be described as neu-
tral or as having the following deviations: anterior-
posterior pelvic tilts, right-left lateral tilts, or right-
left rotations. These deviations from neutral can be
temporary movements that accompany movements of
the spine or femur as described later in this chapter
(see Pelvic and Hip Mechanics, p. 181). They can
also be small deviations that tend to persist and to
be habitual in standing posture or movement, as
will be described now. When identifying pelvic align-
ment or movement, the relative position of bony
landmarks such as the iliac crests, ASIS, PSIS, and
pubic symphysis are used. (Text continues on p. 177.)“Think of Your Pelvis as a Basin and Avoid Spilling the Contents”
T
he instruction to “imagine your pelvis is a basin and avoid having the contents spill out by letting
it tip” is sometimes used by teachers in an effort to maintain desired alignment of the pelvis. From
an anatomical perspective, the directive parallels the concept of a neutral pelvis and avoiding letting
the pelvis tilt, particularly in an anterior direction. The problem with this image is that the pelvis is not
horizontal but has an angle of inclination. Furthermore, a student who is accustomed to dancing with
an anterior pelvic tilt will generally feel that the pelvis is “level.” So it is frequently necessary to use tactile
or visual cues such as placing the hands on the ASIS and noting when they are vertically aligned relative
to the pubic symphysis to identify a neutral position (see Tests and Measurements 4.1, p. 179). Then, the
basin or bowl image can often be successfully used to achieve the desired pelvic alignment.