Dance Anatomy & Kinesiology

The Upper Extremity 427

stabilize the joints and generate movements. As with
the foot, there is a strong fascia that helps stabilize
the joints (palmar aponeurosis) and maintain the
cupped shape of the palm of the hand. The shape
and arrangement of the carpals and difference in
mobility of the carpometacarpal joints make the palm
slightly concave anteriorly, vital for protection of the
nerves, tendons, and blood vessels that cross the hand
anteriorly. There are also retinacula that help keep the
tendons in position. For example, the flexor retinacu-
lum (composed of the palmar carpal and transverse
carpal ligaments) helps hold the flexor tendons close
to the wrist and prevents them from coming away from
the bones when the wrist is flexed. Synovial sheaths
surround many of the tendons in this area to help
facilitate movement and diminish friction. Two small
sesamoid bones are located on the palmar side of the
metacarpophalangeal joint of the thumb, between
which the long flexor of the thumb runs.

Muscles of the Wrist and Hand

There are approximately 25 primary muscles (some
with multiple components) that perform functions

at the wrist and hand. Many of these muscles pro-

duce multiple actions, and an intricate coordination

of muscles acting as prime movers, stabilizers, and

synergists is often required to achieve the desired

movements of the wrist and hand. A brief overview of

these muscles follows. A summary of the attachments

and actions of the extrinsic muscles of the wrist and

hand is provided in table 7.8, while a summary of

fundamental movements of the wrist and hand, and

the extrinsic and intrinsic muscles that can produce

them, is provided in table 7.9. Readers interested in

a more thorough presentation are referred to the

anatomy texts listed in the References and Resources

at the back of the book.

Primary Muscles of the Wrist

There are six primary muscles that act on the wrist

joint—flexor carpi radialis, palmaris longus, flexor

carpi ulnaris, extensor carpi radialis longus, extensor

carpi radialis brevis, and extensor carpi ulnaris (fig-

ures 7.49 and 7.50). There are also extrinsic muscles

of the hands that cross the wrist joint and can assist

with movements of the wrist as shown in table 7.8.

As with the feet, many of the names of these muscles

FIGURE 7.48 Movements of the (A) wrist, (B) fingers 2 through 5, and (C) thumb.

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