3. Central Neural System :-
It is one of the largest organs in the body, and coordinates most body activities.
It is the center for all thought, memory, judgment, and emotions.
Each part of the brain is responsible for controlling different body functions, such as temperature regulation
and breathing, circadian rhythm of our body and human behavior.
The human brain is the central organ of the human nervous system and with the spinal cord makes up the
central nervous system.
Weight of the brain is 1500 grams 1.e. About 2% of the total body Weight.
8. Cerebral cortex :-
Cerebral cortex is also called pallidum and it consists of two hemispheres. Surface
area of cerebral cortex in human beings is 2.2 sq m.
A deep cleft divides the cerebrum longitudinally into two halves, which are termed
as the left and right cerebral hemispheres. The hemispheres are connected by a
tract of nerve fibres called corpus callosum.
Surface of the cerebral cortex is characterized by complicated pattern of sulci
(singular = sulcus) and gyri (singular = gyrus). Sulcus is a slight depression or
groove and gyrus is a raised ridge.
The cerebral cortex is referred to as the grey matter due to it’s greyish appearance.
9.
10.
11. Basal Ganglia :-
Basal ganglia are the scattered masses of gray matter submerged in subcortical
substance of cerebral hemisphere .Basal ganglia form the part of extrapyramidal system,
which is concerned with motor activities.
COMPONENTS OF BASAL GANGLIA
Basal ganglia include three primary components:
1. Corpus striatum
2. Substantia nigra
3. Subthalamic nucleus of luys
12. Hippocampus:-
Hippocampus is a complex brain structure embedded deep into temporal
lobe.
It has a major role in learning and memory(Short term and long term) . It
is a plastic and vulnerable structure that gets damaged by a variety of
stimuli. Studies have shown that it so gets affected in a variety of
neurological and psychiatric disorders.
Amygdala:-
Deep Within temporal bone.
Emotional response.
Autonomic response associated with fear.
13. Thalamus:-
The thalamus is a paired gray matter structure of the diencephalon
located near the center of the brain. It is above the mesencephalon,
allowing for nerve fiber connections to the cerebral cortex in all
directions .
Function:
The primary function of the thalamus is to relay motor and sensory
signals to the cerebral cortex. It also regulates sleep, alertness, and
wakefulness.
14. Hypothalamus:-
Hypothalamus lies at the base of the thalamus.
The hypothalamus contains a number of centres which control body
temperature, urge for eating and drinking. It also contains several
groups of neurosecretory cells, which secrete hormones called
Hypothalamic hormones.
The hormones produced in the hypothalamus are corticotrophin
releasing hormone, dopamine, growth releasing hormone, somatostatin,
gonadotrophin releasing hormone and thyrotrophin releasing hormone.
15. Mesencephalon
.⚫Tectum:-
Tectum is formed by two structures:
1. Superior colliculus
2. Inferior colliculus
Superior Colliculus
Superior colliculus is a small structure and is an important center for reflexes.
Through tectospinal tract, superior colliculus controls the movements of the
eyes, head, trunk and limbs, in response to visual impulses.
Inferior Colliculus
Inferior colliculus is the center for auditory reflexes. Stimulation of this also
produces reflex vocalization.
16. ⚫CEREBRAL PENDUNCLES:-
The cerebral peduncles are the two stalks that attach the
cerebrum to the brainstem.
They are structures at the front of the midbrain which arise
from the ventral pons and contain the large ascending
(sensory) and descending (motor) nerve tracts that run to
and from the cerebrum from the pons.
17. METENCEPHALON
Pons:-
The pons (Latin bridge) is also called metencephalon,2.5 cm long and extends from
cranial end of medulla oblongata to the cerebral peduncles of midbrain.
Cranial nerves V, VI, VII, and VIII are attached here.
Pons develops from cranial metencephalic part of rhombencephalic vesicle.
Pons contains the pneumotaxic and apneustic centers for regulation of respiration.
Pons relays and regulates the signals that give sensation of pain from anywhere in
body below neck.
18. Cerebellum:-
Cerebellum (Latin small brain), though small in size (weighs about 150
grams), subserves important functions for maintaining tone, posture, and
equilibrium of the body. It is the largest part of the hindbrain and second
largest part of the brain.
Cerebellum controls the same side of the body directly or indirectly. The
cerebellum contributes to coordination, language and accurate timing.
Drinking alcohol, for example, has an immediate effect on the cerebellum
and leads to disruptions in the body’s coordination and movements. People
who are severely intoxicated might find that they cannot even walk in a
straight line.
19. Medulla oblongata:-
The medulla oblongata or simply medulla is a long stem-like
structure which makes up the lower part of the brainstem.
It is anterior and partially inferior to the cerebellum. It is a
cone-shaped neuronal mass responsible for autonomic
(involuntary) functions, ranging from vomiting to sneezing.
The medulla contains the cardiac, respiratory, vomiting and
vasomotor centers, and therefore deals with the autonomic
functions of breathing, heart rate and blood pressure as well
as the sleep–wake cycle.
20. BRAIN STEM
Consists of:
(1) Midbrain
(2) Pons
(3) Medulla oblongata
Superiorly continuous with Diencephalon
Inferiorly continuous with spinal cord.
Posteriorly pons and medulla is separated by fourth ventricle.
Midbrain, pons and medulla connected to cerebellum by superior, middle and inferior cerebellar peduncle resp.
21. Ventricles of brain:-
There are certain cavities in the Brain called as”Ventricles”.
These ventricle is filled with CSF.
There are 4 ventricles of Brain.
1. 2 lateral ventricle in two hemisphere of Brain.
• 2 lateral ventricle in two hemisphere of Brain.
• 3rd lies between hypothalamus and thalamus.
• 4th between Brain stem and cerebellum.
22.
23. Cranial Nerve:-
• The 12 pairs of cranial nerves named because they pass through bones of cranium &
arise from the brain inside the cranial cavity.
• These nerves may be sensory(carrying impulse to the brain), motor (carrying impulse
from the brain to periphery) or mixed (containing both sensory & motor fibers)
