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Structures of the Brain
Welcome To Your Brain!
• Your brain is the central site of processing in the entire body• It is responsible for the majority
of thoughts and actions that happen in your body• What makes you act and think
like you, is the neurons in your brain
Welcome To Your Brain!
• A typical brain is around 3lbs and contains around 97% of the bodies neural tissue• Male brains are typically around
10% larger• However that has no link between
brain size and intelligence
• Brains can vary greatly in size from 750ml to 2100ml with a normalized average of 1200ml
Welcome To Your Brain!
• Your brain has a unique ability to structure its neurons to be able to interpret and understand the world around us• The structure of the neurons
dictates what our brains do• At the same time, the structure
of our neurons can often mislead us…
• https://www.youtube.com/watch?v=sxwn1w7MJvk• https://www.youtube.com/watc
h?v=rN7AN0GnwqI• https://www.youtube.com/watc
h?v=tjFxMKEkGjE&index=21&list=PLCv6T8QWRwjkkK_fbUcV8V6Qb2L4xpJSU
Video
• The only way to experience the brain is through seeing one• This is a surgery of a bleed that is
disrupting brain function sent by a student• WARNING… it is surgery• WARNING… it is bloody• WARNING… You will see the bleed
where the blood is coming from• However, it is really cool!
• https://www.youtube.com/watch?v=Ji7fohBEPnM&app=desktop
Parts of the Brain
• The brain is split into seven major sections• These sections include• The cerebellum• The medulla oblongata• The pons• The midbrain• The diencephalon • The cerebrum• The Hippocampus
Parts of the Brain
• The cerebrum is considered the “adult brain” and it is located outside all of the other brain materials• It is covered by layers of
scrunched cerebral cortex • Cortex is latin for bark
• The cerebrum is responsible for higher mental functions like thoughst, intellect, memory and complex movements
Parts of the Brain
• The cerebrum is also divided into two different hemispheres• The right side of the cerebrum is
separate from the left side of the cerebrum• The two sides of the brain are
called hemispheres• They communicate in an area
called the corpus callosum
https://www.youtube.com/watch?v=ZMLzP1VCANo
https://www.youtube.com/watch?v=lfGwsAdS9Dc
Parts of the Brain
• The cerebellum is partially hidden by the cerebral hemispheres and is located in the dorsal part of the brain• It has a variety of jobs inside of the
motor system • However, the most important is how
it coordinates complex motor functions based on previous motor functions• This helps you learn and repeat
major functions
Parts of the Brain
• The spinal cord connects to the brain at the medulla oblongata
• The inferior portion of the medulla oblongata resembles the spinal cord
• This is the lowest part of the brain stem• The medulla oblongata has two main
functions• It relays spinal information to the rest of
the brain• It is responsible for autonomic function
such as heartbeat, blood pressure and digestion
*Alligators are not ornery because of their medulla oblongata - https://www.youtube.com/watch?v=cu7A8LIzL1o
Parts of the Brain
• The pons connects the cerebellum to the inferior parts of the brain stem • The pons helps divert certain
sensory information to the cerebellum and thalamus• The pons give you subconcous
control over visceral and somatic motor centers
Parts of the Brain
• The midbrain (mesencephalon) is superior to the pons• It serves many purposes• It is a sight for processing some
visual and auditory information• It is responsible for most cranial
reflex procession• It is also important for
maintaining consciousness
Parts of the Brain
• The diencephalon contains both the thalamus and the hypothalamus• The thalamus is an important site for
both incoming and outgoing processing of sensory information• The hypothalamus is rooted in
hormone production, emotion and autonomic functions• The hypothalamus connects the
pituitary gland• This is where the nervous system and
endocrine system linkhttps://www.youtube.com/watch?v=O-rQ3tIabvM
Parts of the Brain
• The hippocampus is a very small section of the brain, however it is a vital section in humans• The hippocampus is located
within the brainstem and is associated with memory, learning and special recognition• Patients who suffer from
Alzheimer's disease suffer from damage to the hippocampus
Development of the Brain
• To fully understand the internal organization of the adult brain we must consider its origins• The nervous system begins as a
hollow tube known as the neural tube• The tube has a fluid filled
internal cavity called the neurocoel
Development of the Brain
• During early development the neurocoel enlarges in three distinct areas • These sections of the brain form
around 3 weeks of age• These create the primary brain
vesicles• Each is named for the position
that it takes relative to the others
Development of the Brain
• The prosencephalon is the most forward of the three• Also called the forebrain• Proso means forward• Enkephalos means brain
• The mesencephalon is the middle segment• Also called the midbrain
• The rhombencephalon is the is the most inferior (location) of the three• Also known as the hindbrain
Further Developments
• In later stages of development the prosencephalon and rhombencephalon are subdivided further• The new divisions are called
secondary brain vesicles• Each divides into two distinct
sections• This gives the brain five distinct
divisions at 6 weeks
Further Developments
• The prosencephalon forms the telencephalon (anterior) and the diencephalon (posterior)• The telencephalon ultimately
forms the cerebrum of the adult brain• The diencephalon (as we already
know) contains the thalamus, the hypothalamus and the pituitary gland
Further Developments
• The rhombencephalon adjacent to the mesencephalon forms the metencephalon• The dorsal portion of the
metencephalon will become the cerebellum and the ventral portion will develop into the pons• The portion of the rhombencephalon
closer to the spinal cord forms the myelencephalon• This will become the medulla
oblangata
Diagram
Ventricles of the Brain
• Neurocoel eventually expands in the growing and developing brain• The neurocoel eventually
expands to form enlarged chambers within the brain• These chambers are called
ventricles
Ventricles of the Brain
• There are four major ventricles that are located within the brain• Each hemisphere contains a
large lateral ventricle• This is formed by the
telencephalon through development
Ventricles of the Brain
• The next ventricle that is seen is the third ventricle• Remember that there are two
lateral ventricles!
• The third ventricle is located within the central region of the brain• It is formed by the diencephalon
Ventricles of the Brain
• The two lateral ventricles and the third ventricle communicate through the interventricular foramen• This is a small set of tubing that
links the two lateral ventricles with the central third ventricle
Ventricles of the Brain
• The fourth ventricle contains sections of the pons, cerebellum and the medulla oblongata• It also narrows and becomes
continuous with the central canal of the spinal cord• This is formed by the metencephalon
and the myelencephalon• The fourth ventricle connects to the
third ventricle by the cerebral aqueduct
Video
• https://www.youtube.com/watch?v=Zm-TsqsgCHc
• Obviously med school students (or similar) for a project…
Cranial Meninges
• The layers that make up the cranial meninges are similar to the ones that make up the spinal meninges• However there are some
differences on how they are structured• This is because of the level of
protection and care that the body uses with the brain
Cranial Meninges
• The cranial dura mater consists of out and inner fibrous layers• The outer layer (superior dura
mater) is fused to the cranial bones giving it an anchor point• The inner layer (inferior dura
mater) is separated from the outer layer by a small gap that contains fluids and blood vessels• The gap is called the dural sinus
Cranial Meninges
• The cranial arachnoid mater consists of the arachnoid membrane and the cells that cross the sub arachnoid space• These cells are called arachnoid
trabeculae• This creates a smooth layer
around the brain that does not follow all of the ridges of the cranial cortex
Cranial Meninges
• The pia mater sticks to the surface of the brain• It anchors itself to the intricate
folding patterns of the brain• It also travels with branches of
the cerebral blood vessels that penetrate the surface of the cerebral cortex• This allows it to keep blood from
the brain
Video
• Things can go wrong…
• https://www.youtube.com/watch?v=zCCD52Pty4A
• Then they can go really wrong…
• http://www.dailymotion.com/video/x17ha6y_monsters-inside-me-s03e03-my-face-eating-parasite_lifestyle
• Start at 30:48