Brain
The Brain is a highly organized ORGAN that
contains approximately 100 billion neurons and
has a MASS of 1.4 Kilograms.
The Brain is Protected by a
BONY Covering called the SKULL.
The SKIN protects the head
and brain.
Brain
• In order for the Brain to perform its functions,
it must have a constant supply of Food and
Oxygen.
• If the Oxygen supply to the brain is cut off
even for a few minutes, the brain will usually
suffer enormous damage. Such damage may
result in DEATH.
Meninges: Dura Mater, Arachnoid Mater, Pia Mater
The Brain is WRAPPED in THREE LAYERS of CONNECTIVE TISSUE
known as the MENINGES:
1. DURA MATER The OUTER Layer is composed of Thick
Connective Tissue.
2. ARACHNOID MATER The THIN, elastic, web-like layer between
the DURA MATER and the PIA MATER.
3. PIA MATER The INNER-most layer, which covers and is bound
to the surface of the brain. It is a FIBROUS LAYER made up of
many Blood Vessels which carry FOOD and OXYGEN to the
Brain.
Meninges: Dura Mater, Arachnoid Mater, Pia Mater
• The meninges are tough layers of tissue which help protect the
brain.
• Cerebrospinal Fluid (CSF) fills space between the meninges. This
provides a protective “cushion” for the brain.
Meninges: Dura Mater, Arachnoid Mater, Pia Mater
Meninges: Dura Mater,
Arachnoid Mater, Pia Mater
Skull
Dura mater
Arachnoid Layer
Pia Mater
Brain
Cerebrum
Cerebrum
•
•
THE CONTROL CENTER OF THE BRAIN.
The LARGEST and most PROMINENT part of the Human Brain.
85% of the weight of a human brain. The Cerebrum takes up
most of the space in the cavity that houses the Brain (the skull).
• Responsible for all the VOLUNTARY (CONSCIOUS) ACTIVITIES
OF THE BODY. It is the site of INTELLIGENCE, LEARNING AND
JUDGMENT.
• The CEREBRUM is divided into TWO HEMISPHERES: THE LEFT
AND RIGHT CEREBRAL HEMISPHERES.
• FUNCTIONS: Speech/Language, Conscious Thought, Memory,
Personality, Vision, Logic and Emotions, Voluntary Movement,
Interpretation of Sensation, and other sensations.
The Cerebrum and Cerebral Cortex
Cerebral
Cortex
The cerebrum’s surface - the
cerebral cortex - is convoluted into
hundreds of folds made of gyri
(singular gyrus) and sulci (singular
sulcus).
The cerebral cortex is where all the
higher brain functions take place.
The Cerebral Cortex
The Cerebral Cortex
• Folds in the cerebral cortex increase the surface area of the brain.
• What does this tell you about the importance of the tissue in the
cerebral cortex?
The Cerebral Cortex
The cerebral cortex is a thin layer of cells about 1.5
to 4 mm thick.
The cortex provides the connections and
pathways for the highest cognitive functions,
such as language and abstract thinking.
The cerebral cortex contains about 25 billion neurons,
more than 62,000 miles of axons, and
300,000,000,000,000 synapses.
Cerebral Cortex
The thin layer of the
cerebral cortex is
dense with neurons.
The Cerebrum
The Corpus Callosum is the
fibrous tract of white matter that
connects the right and left
cerebral hemispheres.
The cerebrum is often divided into
five lobes that are responsible for
different brain functions.
1. frontal lobe
2. temporal lobe
3. parietal lobe
4. occipital lobe
5. limbic lobe
Corpus callosum
The Cerebrum
• Different parts of the brain
have different functions.
• Often, several parts or
regions coordinate (work
together) to perform
specific functions, such
as speaking.
Lobes of the Cerebrum
Frontal Lobe
Parietal Lobe
Occipital Lobe
Temporal Lobe
Limbic Lobe
Frontal Lobe
Contains the Primary Motor
Cortex (controls voluntary
movements of specific body
parts).
Area of the brain responsible
for higher cognitive
functions.
These include:
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•
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•
•
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Problem solving
Spontaneity
Memory
Language
Motivation
Judgment
Impulse control
Social and sexual behavior
Temporal Lobe
The temporal lobe plays
a role in emotions, and
is also responsible for
smelling, tasting,
perception, memory,
understanding music,
aggressiveness, and
sexual behavior.
The temporal lobe is also
involved in language.
Parietal Lobe
The parietal lobe plays a
role in our sensations of
touch, smell, and taste.
It also processes
sensory and spatial
awareness, and is a key
component in eye-hand
coordination and arm
movement.
The parietal lobe also
contains a specialized
area called Wernicke’s
area that is responsible
for matching written
words with the sound of
spoken speech.
Occipital Lobe
The occipital lobe is at
the rear of the brain.
It controls:
• vision
• recognition
Limbic Lobe
The limbic lobe is
located deep in the
brain, and makes up
the limbic system.
Functions:
• regulates emotion and
memory
• connects the lower and
higher brain functions
The Limbic System
A.
B.
C.
D.
E.
F.
Cingulate gyrus
Fornix
Anterior thalamic
nuclei
Hypothalamus
Amygdaloid nucleus
Hippocampus
Cerebellum
The cerebellum is connected to
the brainstem.
Functions:
• “autopilot” for body movement
and balance.
The Ventricles
• a complex series of spaces
and tunnels through the center
of the brain
• secrete cerebrospinal fluid
(CSF), which suspends and
protects the brain in the skull.
• provide a route for “chemical
messengers” that are widely
distributed through the central
nervous system.
The Ventricles
**Cerebrospinal Fluid (CSF) circulates from Lateral Ventricles into Third Ventricle and
through the cerebral aqueduct into the Fourth Ventricle.
The Ventricles and Cerebrospinal Fluid
The Cerebrospinal Fluid (CSF) is a
clear liquid that PROTECTS the
Brain from mechanical injury by
acting as a Shock Absorber.
**CSF fills space in the meninges
and fills four interconnected
VENTRICLES, or cavities in the
brain.
Within the Ventricles, CSF acts as
a Transport Medium for
substances that are important to
Brain Function.
**Cerebrospinal Fluid (CSF) circulates from Lateral Ventricles into Third Ventricle and
through the cerebral aqueduct into the Fourth Ventricle.
Cerebrospinal Fluid (CSF)
Cerebrospinal fluid is a
colorless liquid that bathes
the brain and spine.
It is formed within the
ventricles of the brain, and it
circulates throughout the
central nervous system.
Cerebrospinal fluid fills the
ventricles and meninges,
allowing the brain to “float”
within the skull.
Diencephalon and Brainstem
Diencephalon and Brainstem
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Diencephalon = Thalamus + Hypothalamus + 3rd Ventricle
Thalamus
Thalamus means “inner room” in Greek, as it sits
deep in the brain at the top of the brainstem.
The thalamus is called the gateway to the
cerebral cortex, as nearly all sensory inputs pass
through it to the higher levels of the brain.
• Relays sensory
and motor
signals to
cerebral cortex.
• Regulates sleep,
consciousness,
alertness
Hypothalamus
The hypothalamus sits under the thalamus at
the top of the brainstem. Although the
hypothalamus is small, it controls many critical
bodily functions:
• Controls autonomic nervous system
• Center for emotional response and
behavior
• Regulates body temperature
• Regulates food intake
• Regulates water balance and thirst
• Controls sleep-wake cycles
• Controls endocrine system
The hypothalamus is shaded
blue. The pituitary gland extends
from the hypothalamus.
Brainstem: 3 Divisions
Midbrain
Pons
Medulla Oblongata
The Brainstem
The most primitive part of the
brain.
Controls the basic functions of
life:
• autonomic survival
behaviors
• breathing
• heart rate
• swallowing
• reflexes to sight or
sound
• sweating
• blood pressure
• sleep
• balance
The Midbrain (mesencephalon)
Midbrain
Pons
Small portion at superior end of brainstem.
Holds cerebral aqueduct which connects the 3rd
and 4th Ventricles.
Associated with
• vision
• hearing
• motor control
• sleep/wake/arousal (alertness)
• temperature regulation
Medulla Oblongata
The Pons
The rounded brainstem region
between the midbrain and the
medulla oblongata. In fact, pons
means “bridge” in Latin.
Main functions:
• to connect the cerebellum to
the rest of the brain
• to modify the respiratory output
of the medulla (to control
breathing).
The origin of several cranial nerves.
The Medulla Oblongata
The medulla oblongata merges seamlessly
with the spinal cord and creates the base
of the brainstem. The medulla is also the
origin of many cranial nerves.
The medulla is primarily a control center
for vital involuntary reflexes such as:
• swallowing
• vomiting
• sneezing
• coughing
• regulation of cardiovascular activity
(heart rate, blood pressure)
• regulation of respiratory activity
(breathing)
Mamillary Bodies
Functions:
• sense of smell
• processing of
recognition memory
*The Mammillary bodies are
considered part of the
diencephalon.
Mamillary Bodies