Hemorrhoids are classified into two general categories: internal and external. Internal hemorrhoids lie far enough inside the rectum that you can't see or feel them. They don't usually hurt because there are few pain-sensing nerves in the rectum. Bleeding may be the only sign that they are there. Sometimes internal hemorrhoids prolapse, or enlarge and protrude outside the anal sphincter.
Cerebrospinal fluid (CSF) collection is a test to look at the fluid that surrounds the brain and spinal cord. CSF acts as a cushion, protecting the brain and spine from injury. The fluid is normally clear. The test is also used to measure pressure in the spinal fluid. See also: CSF culture.
Cerebrospinal fluid is a clear liquid that cushions the brain and spinal cord while also transporting nutrients, chemicals, and waste. Dura mater is also the home to meningeal veins. Many types of medical conditions involve the dura mater. The most common come in the form of hematomas. Arterial bleeding can result in an epidural hematoma, which is when blood collects between the dura mater and the skull.