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