Which sign is tested by flexing the hip while the knee is bent to the chest?

The sign tested by flexing the hip while the knee is bent to the chest is known as Kernig's sign. This neurological sign is particularly valuable in assessing meningeal irritation, which can occur in conditions like meningitis. When the hip is flexed at a 90-degree angle and attempts are made to extend the knee, if the patient experiences resistance or pain, this indicates a positive Kernig's sign.

In contrast, Brudzinski's sign is tested by passively flexing the neck, which results in involuntary flexion of the knees and hips. Thyromegaly refers to an enlargement of the thyroid gland and is not related to the signs of meningeal irritation. Meningismus is a collection of signs and symptoms indicative of meningeal irritation, but it encompasses a broader range of clinical features rather than a specific test like Kernig’s sign. Each of these alternative options serves different clinical purposes, making Kernig's sign the clear focus for this question.