CENTRAL NERVOUS SYSTEM
CENTRAL NERVOUS SYSTEM (CNS)
·
SPINAL CORD
The spinal cord is a
long, thin bundle of nervous tissue and support cells connected to the brain
and located along your back and neck.
All the sensory
information from various parts of the body are received here and then sent to
higher parts of the brain.
All motor information
from brain first enters spinal cord and then sent to different parts of body
for action. Besides this, the spinal cord also functions as center of reflex
actions.
·
BRAIN
The brain is the organ
located within the skull that is responsible for cognition, mental processes,
and control of the body and its functions.
Within the skull, the
brain is protected by three layers of tissues called meninges.
The brain is divided into
three parts, which is as given below ;
A.
Hind Brain ( Medulla, Pons, Cerebellum and
Reticular Formation)
B.
Mid Brain ( Situated between Forebrain and Hindbrain
)
C.
Fore Brain ( Thalamus, Hypothalamus and
Cerebrum )
A.
HIND BRAIN – The first and foremost structure
of Hind brain is Medulla.
· Medulla: Medulla connects higher parts of
the brain with spinal Cord.
· Pons : It’s located above the medulla. It contains
different types of sensory and motor neurons. It receives sensory information
from some parts of face and head and sensations of touch, pain and temperature.
It also regulates motor activities related to facial expressions, muscular
activities, eye balls and Jaw movement.
·
Cerebellum : Its outer structure is composed of grey matters while
inner structure is made up of white matter. It’s main function is to coordinate
motor activities. Destruction of cerebellum leads to lack of coordination as
for example- “ A person can walk but his pace/step would be disorganized.”
·
Reticular Formation : The reticular formation is a part of the brain that
is involved in actions such as Awaking/Sleeping cycle process.
B.
MID BRAIN – It acts as a bridge between
forebrain and Hind Brain . It has two subdivisions called: (1)
Tectum
(2) Tegmentum
· Tectum – It has
a pair of structures called :-
1)
Superior Colliculi – is roof and concerned with Visual
Information.
2)
Inferior Colliculi – is on the floor and deals with
auditory information.
· Tegmentum – It lies
below tectum. It has some important structures, end of reticular formation an
nuclei controlling the activities of eye movements.
C.
FOREBRAIN – It is the most important part of
the brain. This portion of brain regulates and controls all higher and complex
activities of human beings. Ex : Thinking, Reasoning and Memory.
· It divides it
into two parts :-
1.
Telencephalon – includes Cerebral Hemispheres, Limbic System and Basal Ganglia.
2.
Diencephalon – it includes Thalamus and Hypothalamus.
· Thalamus – It receives sensory impulses
relating to vision, hearing, pain, taste, and smell and sends them to
appropriate parts of the cerebrum.
· Hypothalamus – It is very important and function
to regulate and control biological motives of hunger, thirst and sex. It also
controls and regulates homeostatic mechanism of our body as for example: “ When
we feel hot it causes us to sweat thereby reducing our body temperature and
when we feel cold it causes us to shiver thereby raising our body temperature.
· Basal Ganglia
– It plays an
important role in coordinating movement. Legs and Hands.
· Limbic System
– It’s a collective
term referring to several brain parts.
· The Cerebrum – Divided into 4 parts :
1.
Frontal Lobe – motor function, aggression and mood.
2.
Parental Lobe – reception and sensory information.
3.
Temporal lobe – smell, hearing, memory and thoughts.
4.
Occipital Lobe – Visual processing.
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