What is being tested with the Kernig sign?

The Kernig sign is a specific clinical test used to assess for meningeal irritation, which can be indicative of conditions such as meningitis. During the test, a patient is asked to lie flat, and then the healthcare provider flexes the patient's hip and knee to 90 degrees. When the knee is straightened, if the patient experiences pain and resistance during this extension, it is considered a positive Kernig sign. This response suggests irritation of the meninges due to potential inflammation or infection.

The other options do not reflect the purpose or method of the Kernig sign. For instance, flexion of the hip without knee extension does not assess the same pathology and does not involve the typical presentation or response required to suggest meningeal irritation. Similarly, movement of the arms with neck rotation does not pertain to assessing meningeal signs; it might test other neurological functions but is not relevant to this specific sign. Lastly, flexibility of the spine in general does not provide the specific insights into meningeal irritation that the Kernig sign aims to evaluate. Therefore, the correct answer highlights the critical clinical aspect of assessing pain and resistance during knee extension that indicates potential meningeal issues.