Which sign is tested by flexing the neck and observing involuntary bending of the hips and knees?

Which sign is tested by flexing the neck and observing involuntary bending of the hips and knees?

• A. Kernig's sign
• B. Brudzinski's sign
• C. Nuchal rigidity sign
• D. Babinski sign

Answer: (B)

This sign reflects irritation of the meninges. When you passively flex the neck, the nervous system reflexively causes the hips and knees to bend, producing a flexion of the lower limbs. That reflexive response is Brudzinski's sign and is classically seen with meningitis or other meningeal irritation. Understanding helps: meningitis inflames the membranes around the brain and spinal cord, and Brudzinski's sign arises from that irritation triggering the automatic flexion of the lower limbs. This is different from Kernig's sign, which involves pain or resistance when extending the knee with the hip flexed at 90 degrees, and from nuchal rigidity, which is just neck stiffness without the accompanying reflex leg movement. Babinski sign, on the other hand, is an upper motor neuron finding with plantar extension, not related to meningeal irritation.

This sign reflects irritation of the meninges. When you passively flex the neck, the nervous system reflexively causes the hips and knees to bend, producing a flexion of the lower limbs. That reflexive response is Brudzinski's sign and is classically seen with meningitis or other meningeal irritation.

Understanding helps: meningitis inflames the membranes around the brain and spinal cord, and Brudzinski's sign arises from that irritation triggering the automatic flexion of the lower limbs. This is different from Kernig's sign, which involves pain or resistance when extending the knee with the hip flexed at 90 degrees, and from nuchal rigidity, which is just neck stiffness without the accompanying reflex leg movement. Babinski sign, on the other hand, is an upper motor neuron finding with plantar extension, not related to meningeal irritation.