Outermost layer of brain

Mid-Sagittal Cross Section of BrainThe central nervous system (CNS) includes the brain and the spinal cord. The CNS is protected by bones and the meninges (the dura mater, arachnoid and pia mater). Cerebrospinal fluid cushions the CNS from damage. There are 86 main nerves branching off from the CNS – 12 pairs of cranial nerves that branch off from the brain and 31 pairs of spinal nerves that branch off from the spinal cord.

The brain, which is housed in and protected by the bones of the skull, makes up all parts of the central nervous system above the spinal cord. A human brain can weigh up to 3 pounds and is one of the largest organs of the body. Like the spinal cord, the brain is made of mainly gray matter and white matter arranged in distinct layers. The top of the brain appears as a soggy, pinkish-gray mass that looks like a walnut.

Parts of the Brain

Coronal brain viewThe brain consists of the:

  • cerebrum
  • cerebellum
  • brain stem
  • diencephalon (thalamus and hypothalamus)
  • limbic system
  • reticular activating system

The brain can be divided into two major parts: the lower brain stem and the higher forebrain.

The brain stem sits above the spinal cord and has many connections between them. The brain stem, the most primitive part of the brain, is made up of the medulla, pons, cerebellum, midbrain, hypothalamus and thalamus. The cerebral cortex, limbic system and basal ganglia make up the forebrain. The forebrain deals with homeostasis, emotions and conscious actions.

The brain’s outer layer is only 1/4 inch thick but if flattened out would cover the size of an office desk. It has about 50 billion nerve cells. The cerebrum is the largest part of the brain and is part of the forebrain. It houses the nerve center that controls sensory, motor activities and intelligence. The outer layer, the cerebral cortex, is made of nerve fibers called gray matter. The inner layer is made of a different type of nerve fibers called white matter. The basal ganglia is found in the white matter. The cerebrum is divided in to left and right hemispheres. The left half controls the right side of the body and the right half controls the left side of the body. A mass of nerve fibers known as the corpus callosum connects the two hemispheres and allows communication between the two. The surface of the cerebrum is made up of gyri and sulci.

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Q&A

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How do I schedule a mental status evaluation? | Yahoo Answers

John ... start by seeing your regular physician. They will give you a full blood workup checking for things like blood sugar disorders and glandular problems. If they don't find anything, then see a psychiatrist for diagnosis and treatment. There are very good medicines today to treat most mental disorders and well as therapy once the medication(s) take effect. Take care of yourself by eating healthy, doing cardio exercise and getting quality sleep, which are also needed for positive brain chemistry. Chip

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