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Wesley Goree

April 19, 2015

Principles of Disease

Chap. 21 Review Questions

1. The central nervous system consists of the brain and spinal cord, surrounded by several membranes called meninges. The firm, fibrous outer membrane is called the dura. The thin inner membrane, which adheres to the surface of the brain and spinal cord, is called the pia. The middle membrane, interposed between the pia and the dura, is called the arachoid. The space between the arachnoid and the underlying pia is called the subarachnoid space. It contains cerebrospinal fluid. Cerebrospinal fluid is a clear, colorless bodily fluid found in the brain and spine. It is produced in the choroid plexus of the brain.

2. The force of a blow to the back of the head may displace the brain forward, injuring the front of the brain where it strikes against the front of the bony cranial cavity.

3. A stroke is any injury to the brain caused by disturbance of its blood supply. Ischemic strokes occur when the arteries to your brain become narrowed or blocked, causing severely reduced blood flow. The most common ischemic strokes include: Thrombotic stroke. A thrombotic stroke occurs when a blood clot forms in one of the arteries that supply blood to your brain. A congenital aneurysm is a bulging, weak area in the wall of an artery that supplies blood to the brain.

4. Congenital hydrocephalus is usually caused by a congenital abnormality in the ventricular system, either a congenital obstruction or abnormal formation of the cerebral aqueduct, a narrow channel connecting the third and fourth ventricles, or failure of the openings in the roof and lateral walls of the fourth ventricle to form normally, which blocks escape of cerebrospinal fluid into the subarachnoid space. With a brain tumor, acquired hydrocephalus develops after the skull bones fuse, and the skull cannot enlarge as in the congenital form of hydrocephalus.

5. Neural tube defect is the failure of either end of the neural...