Page 72 - Handbook of Electronic Assistive Technology

Chapter 3 • Functional Posture 59

FIGURE 3-5 Diagram of a typical pattern of spasticity seen in a person after a stroke: note the flexion and
adduction of the shoulder, flexion of the elbow, wrist and fingers�

These contractions resulting in torsion and twisting movements can be very painful.
Similar to spasticity, dystonia may be focal (confined to one particular muscle group) or
more generalised (involving multiple body segments and muscle groups).

What Is a Reflex?
A reflex consists of a motor act that is elicited by a specific sensory input. Primitive reflexes
appear at birth and become integrated as the motor system develops and more compli-
cated movements emerge (Green, 2004). The primary purpose of the postural reflexes is to
maintain a constant posture in relation to a dynamic external environment. For example,
the postural reflexes need to develop and react to the presence of gravity due to the earth’s
gravitational field. When the CNS is damaged, these primitive reflexes can again dominate
motor activity and contribute to abnormal patterns of movement and posturing.
Primitive reflexes that may be retained or reemerge as a result of damage to the CNS
influencing an individual’s postural control are:

Symmetrical tonic neck reflex. This is demonstrated by increased flexor tone in the
upper limbs and extensor tone in the lower limbs when the neck is flexed, and increased
extensor tone in the arms and flexor tone in the legs when the neck is extended.
Asymmetrical tonic neck reflex (ATNR). This is when rotation of the neck and head
causes extensor tone in the limbs on the face side and flexor tone in the limbs of the
skull side.
Positive support reaction. Pressure applied to the ball of the foot stimulates a full
limb extensor pattern.