Final answer:
A typical flexion synergy pattern in the upper extremities involves coupled movements such as adduction and internal rotation of the shoulder, flexion of the elbow, and flexion of the wrist and fingers. This pattern is often seen in individuals with neurological injuries and inhibits functional use of the limb.
Step-by-step explanation:
The typical flexion synergy pattern observed in the upper extremities is a motor response seen primarily in individuals with neurological impairments, where movements are coupled together due to abnormal muscle activation. When a flexion synergy pattern is present in the upper extremity, it often involves the shoulder being adducted and internally rotated, the elbow being flexed, and the wrist and fingers curling into flexion. This pattern can inhibit functional use of the limb as the muscles work in unison rather than coordinating separately for deliberate movements.
Description of Flexion Synergy Pattern:
Flexion synergies are observed when the biceps brachii flex the lower arm, and are aided by the synergistic action of the brachoradialis and brachialis. These patterns are exacerbated in conditions such as after a stroke, where the nervous system's regular pattern of muscle activation is disrupted, leading to the automatic coupling of certain movements. In a healthy individual, the muscles can activate independently for complex, coordinated movements, but the typical synergy pattern seen post-injury often involves these muscles contracting together in a stereotypical, primitive pattern that limits functional movement.
In a deeper context of joint movement, flexion reduces the angle between bones at a joint, while extension increases this angle. For example, when the arm flexes at the shoulder, the forearm at the elbow, or the fingers at the joints within the hand, these actions are manifestations of flexion or extension depending on the direction of the movement. Understanding these basic definitions is essential for identifying abnormal synergy patterns in clinical practice and for developing therapeutic interventions to address them.