INTRODUCTION TO THE BRAIN by Professor Fink
Summary
TLDRThis lecture discusses the brain's anatomy, focusing on the corpus callosum's role in connecting the brain's hemispheres. It explains the cerebrum's function in consciousness and voluntary movement, and delves into the cerebral cortex, limbic system, and basal ganglia. The thalamus's sensory relay function and the hypothalamus's role in homeostasis are highlighted. The cerebellum's coordination of complex movements and the brainstem's control over vital functions are also covered. The lecture concludes with an overview of the 12 pairs of cranial nerves.
Takeaways
- π§ The corpus callosum is the largest commissure in the central nervous system, connecting the right and left hemispheres of the brain.
- π€ The cerebrum is the part of the brain responsible for consciousness and voluntary movement.
- 𧬠The cerebral cortex is the outermost part of the cerebrum, involved in higher cognitive functions.
- β€οΈ The limbic system, part of the cerebrum, is the center of emotions.
- πββοΈ The basal ganglia, or subcortical nuclei, are involved in voluntary skeletal muscular activity.
- ποΈ The thalamus acts as a sensory relay station, processing information from the spinal cord and other senses.
- π‘οΈ The hypothalamus is crucial for homeostasis, controlling body temperature and other reflex centers.
- π§ The pituitary gland, attached to the hypothalamus, is the master endocrine gland, controlling hormone release.
- ποΈββοΈ The cerebellum coordinates complex skeletal muscular activity, essential for activities like riding a bicycle or dancing.
- π³ The brainstem consists of the midbrain, pons, and medulla oblongata, regulating vital functions like heart rate and breathing.
- π There are 12 pairs of cranial nerves branching from the brain, each with a specific function and numbered from front to back.
Q & A
What is the corpus callosum and what is its function?
-The corpus callosum is the largest commissure in the central nervous system, containing about 300 million nerve fibers that connect the right and left sides of the brain. It facilitates communication between the two hemispheres, allowing for integrated functioning.
What would happen if the corpus callosum was severed?
-If the corpus callosum were severed, the right side of the brain would not know what the left side was thinking, and vice versa, leading to a disconnection of cognitive processes between the two hemispheres.
What part of the brain is responsible for consciousness and voluntary movement?
-The cerebrum is the part of the brain responsible for consciousness and voluntary movement. It is the location where we have conscious awareness of our senses and can initiate voluntary movement.
What are the main subdivisions of the cerebrum?
-The cerebrum can be subdivided into the cerebral cortex, the limbic system, and the basal ganglia. The cerebral cortex is the outermost part, the limbic system is the center of emotions, and the basal ganglia are involved in voluntary skeletal muscular activity.
What is the role of the thalamus in the brain?
-The thalamus acts as a sensory relay station, receiving and relaying sensory information from the spinal cord and other parts of the body to the cerebral cortex. It also plays a role in sleep and wake cycles.
What is the hypothalamus and where is it located?
-The hypothalamus is located just below the thalamus and is regarded as the center of homeostasis. It contains the temperature control center and many other reflex centers that maintain internal balance.
What is the function of the pituitary gland and how is it related to the hypothalamus?
-The pituitary gland is the master endocrine gland of the body, and it is attached to the hypothalamus. The hypothalamus controls the release of hormones by the pituitary gland.
What is the cerebellum and what does it do?
-The cerebellum, located on the dorsal side of the brain, is involved in coordinating complex skeletal muscular activity, such as riding a bicycle, swimming, dancing, playing basketball, doing gymnastics, and driving a car.
What are the main parts of the brainstem?
-The brainstem consists of the midbrain, pons, and medulla oblongata. The midbrain is involved in motor commands, the pons coordinates skeletal muscular activity with the cerebellum, and the medulla contains control centers for heart rate, blood pressure, and breathing.
How many pairs of cranial nerves are there and what are they numbered?
-There are 12 pairs of cranial nerves, traditionally numbered with Roman numerals from I to XII, starting from the front (anterior) to the back (posterior) of the brain.
What types of nerve fibers are found in cranial nerves?
-Cranial nerves can be mixed, containing both sensory and motor nerve fibers, or they can contain exclusively sensory or motor nerve fibers.
Outlines
π§ Brain Organization and Function
The script discusses the anatomy and function of the brain, focusing on the corpus callosum, a large bundle of nerve fibers that connects the left and right hemispheres of the brain. It plays a crucial role in communication between the two sides of the brain. The cerebrum, responsible for consciousness and voluntary movement, is further divided into the cerebral cortex, limbic system, and basal ganglia. The thalamus, a sensory relay station, and the hypothalamus, the center for homeostasis and control of the pituitary gland, are also highlighted. The script also touches on the reticular activating system and the importance of the brainstem, including the midbrain, pons, and medulla oblongata, which contain vital control centers for heart rate, blood pressure, and breathing.
πΏ The Cerebellum and Cranial Nerves
The second paragraph delves into the cerebellum's role in coordinating complex muscle movements, such as riding a bicycle or swimming. It explains the consequences of cerebellar injury on these movements. The script then describes the brainstem's components, including the midbrain, pons, and medulla oblongata, emphasizing their functions in motor commands and reflexes. It also mentions the 12 pairs of cranial nerves, which emerge from the underside of the brain and are numbered and named, with some being mixed nerves containing both sensory and motor fibers. The script concludes by directing viewers to the next lecture for further details on the cranial nerves.
Mindmap
Keywords
π‘Corpus Callosum
π‘Cerebrum
π‘Cerebral Cortex
π‘Limbic System
π‘Basal Ganglia
π‘Thalamus
π‘Hypothalamus
π‘Pituitary Gland
π‘Cerebellum
π‘Brainstem
π‘Medulla Oblongata
Highlights
The corpus callosum is the largest commissure in the central nervous system.
Corpus callosum contains about 300 million nerve fibers that connect the right and left sides of the brain.
Cutting the corpus callosum would disconnect communication between the brain hemispheres.
The cerebrum is where consciousness and awareness of senses occur.
The cerebrum can initiate voluntary movement.
The cerebral cortex is the outermost part of the cerebrum.
The limbic system, located in the cerebrum, is the center of emotions.
The basal ganglia, also known as subcortical nuclei, play a role in voluntary skeletal muscular activity.
The thalamus is a sensory relay station for information coming up through the spinal cord.
The thalamus is involved in sleep and wake cycles.
The hypothalamus is the center of homeostasis and contains the temperature control center.
The hypothalamus controls the release of hormones by the pituitary gland.
The cerebellum coordinates complex skeletal muscular activity.
Injury to the cerebellum impairs the ability to carry out complex movements.
The brainstem consists of the midbrain, pons, and medulla oblongata.
The midbrain is the location of the extra pyramidal tract which sends motor commands.
The pons coordinates skeletal muscular activity with the cerebellum.
The medulla oblongata contains control centers for heart rate, blood pressure, and breathing.
There are 12 pairs of cranial nerves branching off the underside of the brain.
Cranial nerves are mixed nerves containing both sensory and motor nerve fibers.
Transcripts
what we now want to take a brief look at
is the organization of the brain and so
this is page 70 page 70 in the lecture
outline and now I have by my brain right
here in my own hands and if we were to
make a midsagittal section right through
the middle of the brain which is what we
see in the picture in front of us first
thing I want to draw your attention to
is this area called the corpus callosum
the corpus callosum is the largest
commish or in the central nervous system
and we Britain commish or right here
what's a comma sure a comma saw is a
location of where there are many nerve
fibers that decussate or connect cross
between the right and left sides of the
central nervous system so in fact the
corpus callosum which literally means
big body corpus needs body close close
of like colosso means large this large
body is the location of about 300
million violated nerve fibers that link
the right left sides of our brain
together to connect the two hemispheres
and then if they're one-word to make a
cut through the corpus callosum
literally the right side of their brain
would not know what the left side was
thinking and the left side would not
know what the right side is thinking and
right as the corpus callosum
now this upper part of the brain is the
cerebrum the cerebrum is that part of
the brain where there is consciousness
or awareness of what it's going so it is
in the cerebrum where we have conscious
awareness of our senses and it is also
in the cerebrum where we can initiate
voluntary or volitional movement of our
body now the cerebrum if we look down
in the outline so the cerebrum can be
further subdivided into the really the
outermost part the highest level the
cerebrum is the cerebral cortex then
there is this limbic system the center
of emotions which we will talk more
about later when we look at more details
of the brain and and another part of the
cerebrum were within the cerebral
hemispheres are the so called basal
ganglia also known as the subcortical
nuclei and again we will have more to
say about that part of the cerebrum
later but the basal ganglia or
subcortical nuclei are play a role in
voluntary skeletal muscular activity now
right here it says the thalamus and the
thalamus is the forms the upper part the
upper portion of what is sometimes known
as the reticular activating system or
RNAs it is associated in part with the
winking Center so the thalamus comprises
the winking Center now where is the
thalamus in our picture so in our
picture the thalamus is right here in
the center of the brain right in the
middle of the brain is where the thought
lamech nucleus or thalamus is located
and as we indicated right here it is a
sensory relay station one fact we've
learned that almost all sensory
information certainly all the sensory
information coming up through the spinal
cord including sensory information from
our eyes and our ears a synapse or these
sensory information is relayed to the
thalamus before it is forwarded or
relayed to other parts of the brain
including up to the cerebral cortex
so the thalamus we should know is
important in the relaying of sensory
information to higher levels of the
brain and it
with the winking center it plays a role
in our sleep and wake cycles now an area
of the brain just below just below the
thalamus is called the hypothalamus
which literally means below the thalamus
and it is in the hypothalamus uh that is
regarded as the center of homeostasis
since we know that homeostasis is the
most critical word in this entire
physiology course that makes this small
area of the brain especially important
in a physiology course this is where the
temperature control center is located as
well as many other reflex centers that
play a role with maintaining internal
balance or homeostasis attached to the
hypothalamus is the pituitary gland the
master endocrine gland of the body and
as we will be learning the hypothalamus
also is in control of the release of
hormones by the pituitary gland and now
right over here on the back side the
dorsal side of the brain is the
cerebellum which literally means little
brain and the cerebellum as we wrote is
involved in coordinating complex
skeletal muscular activity in other
words we have learned that the
cerebellum plays a key role in complex
skeletal muscular activity including
riding a bicycle swimming dancing
playing basketball doing gymnastics
driving a car any time therein entails a
coordinated complex skeletal muscular
activity when there is injury to the
cerebellum there's an impaired ability
to carry out these complex skeletal
muscular movements now this is the lower
part of the brain commonly referred to
as the brain stem and the brainstem
consists of an upper portion called the
midbrain a middle part called the
and a lower portion called the medulla
oblongata the upper part of the
brainstem the midbrain we have made
reference to that is the location of
where the extra pyramidal tract or extra
corticospinal tract originates as they
send a motor commands involuntary motor
commands downwards to the somatic motor
neurons of the spinal cord the pons I is
really related to the cerebellum so the
pons really plays a role with the
cerebellum in coordinating skeletal
muscular activity the lowest portion of
the brainstem is called the medulla or
medulla oblongata this is where there
are a number of very important control
centers including a cardio vascular
reflex center that regulates our heart
rate and blood pressure as well as the
respiratory reflux center that regulates
our breathing pattern so those are some
of the more important brain areas
looking at the outline below so we've
mentioned the medulla oblongata and the
midbrain under the brain stem the
cerebellum the hypothalamus the thalamus
and the cerebrum now at the very bottom
of the page seventy so we are reminded
that branching off of the inferior
aspect of the brain the underside are 12
pairs of cranial nerves and we have a
picture of the cranial nerves on page 71
here we're looking at the inferior view
of the brain the underside and
highlighted in yellow are the 12 pairs
of cranial nerves now we're not going to
test you on this picture that would be
anatomy this is a physiology course but
the 12 pairs of cranial nerves are
assigned not
traditionally written in Roman numerals
and they are numbered from front
anterior to back posterior each of these
cranial nerves not only is assigned a
number but has a name so you can see
that this first pair are the olfactory
nerves Roman numeral cranial nerve
roaming over one and the second pair
right left are the optic nerves cranial
nerves Roman numeral number two and then
come the oculomotor cranial nerves right
here right left cranial nerve number
three and so on down the line now we
wrote on the bottom of the previous page
we wrote on the bottom of page seventy
that most of these cranial nerves are
mixed nerves and by mixed nerves we mean
that inside these nerves are both
sensory and motor nerve fibers there are
some cranial nerves that contain
exclusively only sensory nerve fibers
and there are other cranial nerves that
contain exclusively only motor nerve
fibers now on the next page on page 72
is our chart describing the 12 pairs of
cranial nerves and for that information
we will direct you to the next video
lecture in the series which reviews the
12 pairs of cranial nerves
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