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Basic Anatomy of the Brain, Injuries and Pathologies: An Illustrated Review

December 4, 2013

Brain tissue is often described as gelatinous in terms of its texture. Its integrity comes from the three layers of the meninges, especially the tough fibrous dura mater. Although protected by the bony skull and bathed in cerebrospinal fluid, the soft consistency of the brain makes it vulnerable to injury. This primer on the brain and its injuries is meant to be a simple over view. For more detailed information a bibliography is available at the conclusion of this article.

The brain has three parts, the cerebrum, cerebellum and brainstem (made up of the medulla oblongata, pons and midbrain). The largest portion, the cerebrum, is broken down into regions which are named for the parts of they skull they reside in; they are the frontal, parietal, temporal and occipital lobes. The large cerebrum, making up 85% of the brain, is comprised of the right and left hemispheres, which communicate via a thick bundle of nerves called the corpus callosum.

Brain Anatomy

The smaller, posterior cerebellum which helps to coordinate muscular movement and balance, is comprised of two lateral lobes.  Finally the smallest portion of the brain is the brainstem, which communicates with the spinal cord.  The line of demarcation between the brain and the spinal cord is at the point of the foramen magnum (the large hole in the occipital bone.)

A common but important injury often sustained in accidents is a concussion, or a violent shaking of the brain.  These traumatic injuries can alter the brain function but typically over time a full recovery occurs.  The initial impact from a blow to the head is referred to as “coup” and the secondary impact is “contrecoup”.

Concussion

Hematomas, or bleeding in the brain, are referred to as intracranial, subdural or epidural.  A subdural hematoma is one that forms between the dura mater and the brain.  An epidural hematoma collects under the skull and between the dura mater and brain. An intracranial hematoma is one that causes bleeding in the white matter of the brain.

Hematomas

Strokes or cerebrovascular accidents are the rapid loss of brain function due to a disruption in blood supply to the brain.  These can be an ischemic stroke caused by a blockage, such as a thrombosis or plaque, or a hemorrhagic stroke caused when a weak blood vessel ruptures and bleeds into surrounding tissues.

IschemicStroke-Newsletter

HemorrhagicStroke-Ne#8B9E3F

Aneurysms are bulges in a blood vessel.  As aneurysms enlarge they have an increased chance of rupturing and bleeding in the brain (hemorrhagic stroke-see above). Common locations of aneurysms include the cerebral arterial circle at the base of the brain and the aorta.

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Originally published by the Trial Lawyers Association of Metropolitan Washington, DC in their November 2013 newsletter.  All illustrations and written content copyrighted by Compel Visuals.

Bibliography:

From the Society of Neuroscience download the free textbook “Brain Facts, A Primer on the Brain and Nervous System”: http://www.brainfacts.org/about-neuroscience/brain-facts-book/

Netter Collection of Medical Illustrations: Nervous System Parts I and II, By Michael J. Aminoff, Scott L. Pomeroy, M.D., Ph.D. – Elsevier – Health Sciences Division – 2013

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