Dr. Martin's notes

Friday September 09, 2016

Neurology - Day 1

CENTRAL NERVOUS SYSTEM (CNS)
Consists of Brain and Spinal Cord and their coverings (Dura Mater, Pia Mater & Arachnoid)

All functions of the body happen by communication between the brain and the nerve endings (at the organs, muscles, etc)
If you sever the spinal cord from the brain, the body ceases to function.
Partial severing or damage to the spinal cord results in loss of function (paraplegic, quadraplegic)

The neural streak (the beginning of the spinal cord and brain) is the first thing to develop in utero

Nerves are the conductors of neural impulses (like electrical impulses) throughout the body.
The nerve transmits impulses by passing a charge between the internal and external portions of the nerve. This process utilizes sodium and potassium ions to create a wave of polarization and depolarization. (This is a nerve impulse). The nerves are covered in a conductive tissue called myelin sheaths.

Nerves in the brain cross over open spaces called synapses. This is a chemical (not electrical) transfer of energy and needs the proper chemical balance to occur (Loss of chemicals may be the result of bipolar disease or some forms of dimentia.
Drugs such as alcohol, cocaine, marijuana and opiates block some of the synapes from functioning. This is why there is a short euphoria followed by a stupor.

The CNS consists of the brain, Cerebellum (transmitting center), midbrain, pons, medulla oblongata and the spinal cord.
It is covered with three layers of tissue and each is separated by fluid, the cerebro-spinal fluid. The brain and spinal cord float in this fluid.

The importance of oxygen supply to the brain (through the blood vessels) cannot be overemphasized. Neural damage can occur with only a few minutes of lack of oxygen (anoxia). The brain receives it's blood supply through three pairs of vessels, the internal and external carotid and the vertebral arteries. These all join together in the brain at the Circle of Willis

The spinal cord extends off the brain and goes into the spinal canal created by the body, lamina and pedicles of the vertebrae. This creates a very strong protection for the cord. It is the most easily damaged at the cervical spine. The lowest part of the spinal cord (in the lumbars and sacrum) looks like a horse's tail and is called the cauda equina.