Dance Anatomy & Kinesiology

94 Dance Anatomy and Kinesiology

Provance, 1993). A plumb line is a cord with a weight

(plumb bob) attached to its distal end so that when

hung it will provide an absolute vertical line as a

reference for measuring deviations. If one viewed

a dancer from the side, the plumb line would be

aligned with the ankle/foot (just in front of the lat-

eral malleolus, which is the distal end of the fibula).

This would serve as the fixed point. Then, with ideal

alignment the following external landmarks would

all be located right along the plumb line: the lobe

of the ear, middle of the tip of the shoulder, middle

of the thorax, greater trochanter (projection on

lateral femur), just in front of the middle of the

knee, and just in front of the lateral malleolus. Any

of these landmarks that do not fall upon the plumb

line would reflect deviations from ideal alignment.

Assuming that the shoulders are not “rolled,” having

all of these landmarks aligned along the plumb line

generally indicates a very basic correct balance of

the sagittal spinal curves.

From this lateral view, the positioning of the

pelvis should also be noted. With ideal alignment

FIGURE 3.23 Curvatures of the spine. (A) Normal; (B) lumbar lordosis, thoracic kyphosis, and cervical lordosis;

(C) flat back; (D) scoliosis.

extensors and deep posterior spinal group) and the

abdominals (particularly the internal obliques). As

the gravity line continues downward, it runs slightly

posterior to the axis of the hip joint with the result-

ing tendency for hip extension (extensor moment)

limited by the iliofemoral ligaments (LaBan, Raptou,

and Johnson, 1965), and in some cases, slight activ-

ity of the iliopsoas muscle (Basmajian and DeLuca,

1985); just anterior to the axis of the knee, with the

resulting tendency for the knees to extend (extensor

moment) limited by passive constraints (posterior

knee capsule and knee ligaments); and just anterior

to the ankle axis, generally requiring low levels of

activity in the calf muscles (particularly the soleus)

to prevent the body from falling forward (Basmajian

and DeLuca, 1985; Floyd and Silver, 1950; Nachem-

son, 1966; Ortengren and Andersson, 1977).

To utilize the concept of ideal postural alignment

practically, the vertical gravity line is reflected by a

plumb line, and surface landmarks on the body are

used to reflect where this gravity line would actu-

ally run inside the body (Kendall, McCreary, and