Physical Therapy Assistant Practice Exam

What stimulus is most appropriate for assessing the positive support reflex in a two-month-old infant?

1. Weight placed on the thighs while seated

2. Weight placed on the balls of the feet in standing

3. Weight applied to the back of the head

4. Weight placed on the arms while lying down

The correct answer is: Weight placed on the balls of the feet in standing

The positive support reflex is an important developmental response that occurs when an infant demonstrates the ability to bear weight on their legs when in a standing position. When assessing this reflex, the appropriate stimulus involves placing weight on the balls of the infant's feet while they are in a standing position. This position encourages the infant to engage their leg muscles and support their own weight, showcasing their ability to respond to gravitational stimuli. In a two-month-old infant, eliciting the positive support reflex effectively can indicate their neuromuscular development and readiness for further motor skill milestones. Other stimuli mentioned, such as weight on the thighs while seated or weight placed on the arms while lying down, do not specifically engage the muscles required for standing and weight-bearing, which is central to assessing the positive support reflex. Similarly, applying weight to the back of the head does not pertain to the reflex in question, as it does not provoke the necessary reaction in the legs. Therefore, the most appropriate and effective method to assess this reflex is through the stimulus of weight on the balls of the feet while the infant is standing.