Final answer:
Normal CSF pressure ranges from 60-100 mm H₂O or 4.4 -7.3 mm Hg when a person is lying down. This pressure helps provide flotation for the brain, and any significant change can lead to medical issues. Spinal fluid pressure is measured using a manometer for clinical accuracy.
Step-by-step explanation:
The normal cerebrospinal fluid (CSF) pressure when a patient is lying down ranges from 60-100 mm H₂O or 4.4 -7.3 mm Hg, with variations mostly due to coughing or internal compression of jugular veins in the neck. In a sitting position, because of the change in the vertical position of the spinal column relative to the brain, there might be a slight change in pressure measurement due to the column of fluid that is displaced.
However, what is considered 'normal' can depend on the method of measurement and the individual's specifics. It's also important to note that CSF serves purposes such as supplying flotation to the brain, with densities that are nearly equal to the brain's, allowing for a buoyant force that prevents the brain from resting on the skull. Any significant loss of CSF can cause severe headaches, constricted blood flow, and serious damage.
Spinal fluid pressure is typically measured with a needle inserted between vertebrae, transmitting the pressure to a manometer, which provides accurate measurements in clinical settings.