THE SPINAL CORD White Matter of the Spinal Cord Gray Matter of the Spinal Cord and Spinal Roots THE BRAIN Basic Parts and Organizationof the Brain The Brain stem

1. The Central Nervous
System

2. THE SPINAL CORD
The spinal cord is the most important structure between the
body and the brain.
The spinal cord extends from the foramen magnum where it
is continuous with the medulla to the level of the first or
second lumbar vertebrae.
It is a vital link between the brain and the body, and from the
body to the brain.

3. The spinal cord is 40 to 50 cm long and 1 cm to 1.5 cm in diameter. Two consecutive
rows of nerve roots emerge on each of its sides. These nerve roots join distally to
form 31 pairs of spinal nerves.
The spinal cord is a cylindrical structure of nervous tissue composed of white and
gray matter, is uniformly organized and is divided into four regions:
cervical (C), thoracic (T), lumbar (L) and sacral (S),
each of which is comprised of several segments.
The spinal nerve contains motor and
sensory nerve fibers to and from all parts of the body.
Each spinal cord segment innervates a dermatome.

4. White Matter of the Spinal Cord
The white matter of the spinal cord is composed of
myelinated and unmyelinated axons that allow
communication between different parts of the spinal cord
and between the cord and brain.
These fibers are classified as being one of three types,
according to the direction in which they carry nerve
impulses:

5. 1. Ascending. Most of the ascending fibers in the spinal
cord carry sensory information from the sensory neuron
of the body up to the brain.
2. Descending. Most descending fibers carry motor instructions from
the brain to the spinal cord, to stimulate contraction of the body’s
muscles and secretion from its glands.
3. Commissural. A commissure is a bundle of axons that
crosses from one side of the CNS to the other, and commissural
fibers are white-matter
fibers that carry information
from one side of the
spinal cord to the other.

6. Gray Matter of the Spinal Cord
and Spinal Roots
Spinal gray matter is butterfly-shaped.
It extends from the ependymal cells lining the central canal
to the surrounding white matter.
Spinal gray matter is divided bilaterally into dorsal horn,
intermediate substance, and ventral horn.
At thoracolumbar levels, intermediate substance features a
lateral horn.
Intermediate substance
lacks precise boundaries;
in general, it is around the
central canal and between
dorsal and ventral horns.

7. THE BRAIN
The brain performs the most complex neural functions
those associated with intelligence, consciousness, memory,
sensory-motor integration, and so on. In addition to these
higher-level tasks, the brain also controls basic life-sustaining
Activities heart rate, respiratory rate, and maintenance of
blood pressure and maintains the internal environment
through control of the autonomic nervous system and the endocrine
system. Furthermore, through the cranial nerves that attach to it, the
brain is involved in innervation of the head.
It is approximately two large handfuls
of pinkish gray tissue,somewhat the
consistency of cold oatmeal.
The average adult
human brain weighs about 1500 g,
or 3.3 pounds.

8. Basic Parts and Organization
of the Brain
Frontal Lobe
Let's start with the frontal lobe. As you will remember
from the basic anatomy study guide, the frontal lobe is
the front-most part of the brain. It is also the most
diverse lobe of the brain. The frontal lobe is highly
involved in cognitive functions, such as:
Working memory
Judgment, planning, problem solving and reasoning
The frontal lobe, on the left hemisphere, is also the
location of Broca's area. This is a region for language,
involved in forming coherent words and sentences.
Part of the motor cortex is also in the frontal lobe. In
addition, the frontal lobe does have some involvement
in emotions.

9. Parietal Lobe
The next lobe is the parietal lobe, which is behind the frontal lobe located toward the
top of the head. The sensory cortex is located in the parietal lobe, which receives
stimuli regarding:
.Temperature
.Pain
.Pressure
.Touch
Temporal Lobe
The temporal lobe is located behind the frontal lobe and below the parietal lobe. The
main thing to remember about the temporal lobe is that it is involved in memory, as it
contains the hippocampus. The temporal lobe also contains a language section in the
left hemisphere: it is called Wernicke's area, which is involved in understanding
language. The other main function of the temporal lobe is hearing.

10. Occipital Lobe
The last lobe of the cerebrum is the occipital lobe, which is located at
the back of the head. The occipital lobe's main function is vision, which
includes the visual-perception system. The occipital lobe can also
discern color and movement.
Cerebellum
Remember, the cerebellum is separate from the cerebrum. It is located
toward the base of the brain and looks different from the rest of the
brain. The main functions of the cerebellum are the motor skills, such
as:
.Coordination
.Voluntary motor movement coordination
.Balance
.Muscle tone

11. Brain Stem
Remember, the cerebellum is separate from the cerebrum. It is located
toward the base of the brain and looks different from the rest of the brain.
The main functions of the cerebellum are the motor skills, such as:
.Coordination
.Voluntary motor movement coordination
.Balance
.Muscle tone
Although the brain stem is the small, it is responsible for many of the
involuntary actions that are needed to live.

12. The Brain stem
Brainstem - The lower extension of the brain where it
connects to the spinal cord.
Neurological functions located in the brainstem include
those necessary for survival
(breathing, digestion, heart rate, blood pressure) and for
arousal (being awake and alert).
Most of the cranial nerves come from the brainstem. The
brainstem is the pathway for all fiber
tracts passing up and down from
peripheral nerves and spinal
cord to the highest parts
of the brain.

13. Medulla Oblongata
The medulla oblongata functions primarily as a relay station
for the crossing of motor tracts between the spinal cord and
the brain.
It also contains the respiratory, vasomotor and cardiac
centers, as well as many mechanisms for controlling reflex
activities such as coughing, gagging, swallowing and
vomiting..

14. Midbrain
The midbrain serves as the nerve pathway of the cerebral
hemispheres and contains auditory and visual reflex centers.
Pons
The pons is a bridge-like structure which links different parts
of the brain and serves as a relay station from the medulla to
the higher cortical structures of the brain. It contains the
respiratory center.