Protection and Injury to the Brain - PowerPoint Presentation

Slide1

Protection and Injury to the BrainSlide2

Protection of the Brain

Nervous tissue is soft and easily injured. Several systems are in place to protect the brain.Slide3

Meninges

The Meninges consist of three connective tissue membranes that cover the organs of the CNS. They have several functions:

Cover and protect the CNSProtect the blood vessels and venous sinusesContain cerebral spinal fluidForm partitions within the skullSlide4

The three layers are

dura mater

arachnoid materpia mater  (Think DAP) Slide5

Dura Mater

The Dura Mater “tough mother” is composed of two layers of fibrous connective tissue.

The periosteal layer is in contact with the inner surface of the skullThe meningeal layer is the true external coveringThey can form venous sinuses and Dural septa such as the Falx cerebri, Falx cerebelli and Tentorium cerebelli  Slide6

Dural septa and Dural venous sinuses.

Falx cerebri

Superior

sagittal sinus

Straight

sinus

Crista galli

of the

ethmoid

bone

Pituitary

gland

Falx

cerebelli

Occipital lobe

Dura mater

Transverse

sinus

Temporal

bone

(b) Dural venous sinuses

(a) Dural septa

Scalp

Skull

Tentorium

cerebelli

Cerebellum

Arachnoid

mater over

medulla

oblongataSlide7

Falx cerebri

Superior

sagittal sinus

Falx

cerebelli

Occipital lobe

Dura mater

Transverse

sinus

Temporal

bone

(b) Dural venous sinuses

Scalp

Skull

Tentorium

cerebelli

Cerebellum

Arachnoid

mater over

medulla

oblongataSlide8

Arachnoid Mater

This is the middle layer and forms a loose brain covering (looks like a spiders web)

It is separated from the dura mater by a potential space known as the subdural space. Slide9

Pia Mater “gentle mother”

Has a rich supply of blood vessels. It is the only one which clings tightly to the brain and follows every convolutionSlide10

Meningeal Layers

Skull

Epidural SpaceDura MaterSubdural SpaceArachnoid Subarachnoid spacePia Mater  Slide11

Skin of scalp

Periosteum

Falx cerebri

(in longitudinal

fissure only)

Blood vessel

Arachnoid villus

Pia mater

Arachnoid mater

Dura

mater

Meningeal

Periosteal

Bone of skull

Superior

sagittal sinus

Subdural

space

Subarachnoid

space Slide12

Conditions involving the Meninges

Meningitis is an inflammation of the meninges.

It can be, most commonly, of viral or bacterial originThe bacterial form is potentially fatal while the viral form is self limited.Slide13

Signs and Symptoms

Most common signs are:

HeadacheNuchal rigidity (Can’t flex neck)Altered mental status (acting strange)Slide14

Signs and SymptomsSlide15

Conditions involving the Meninges

Brain bleeds can be of three types, epidural, subdural or subarachnoid.Slide16

They can wake up dead

Epidural hemorrhage typically occurs from blood vessels bleeding into the space between the dura mater and the skull.

Often associated with head traumaCharacterized by arterial blood accumulating in the epidural spaceRapid onset because of the arterial bleedingPatients are at first lucid and then decline rapidly Slide17

They can wake up dead

Subdural hemorrhage typically occurs from blood vessels bleeding into the space between the dura and the arachnoid layer.

Often associated with head traumaCharacterized by venous blood accumulating in the subdural space The onset of symptoms is gradual these include confusion and headache. Slide18

They can wake up dead

Epidural Hematoma

Subdural HematomaSlide19

Conditions involving the Meninges

Sub arachnoid hematoma occurs in the space between the arachnoid and pia matter. These typically present with stroke like symptoms. The most common sign is a “thunder clap” headache, vomiting and changes in the level of consciousness.Slide20

Conditions involving the Meninges

Sub arachnoid hematoma usually occurs as a result of a ruptured blood vessel.Slide21

Cerebral Spinal Fluid (CSF)

The CSF is found in on and around the brain and spinal column.

It forms a cushion and allows the brain to float preventing it from crushing itself.Slide22

Cerebral Spinal Fluid (CSF)

CSF has a makeup similar to blood plasma but has less protein. Slide23

Figure 12.26a Formation, location, and circulation of CSF.

Superior

sagittal sinus

Arachnoid villus

Subarachnoid space

Arachnoid mater

Meningeal dura mater

Periosteal dura mater

Right lateral ventricle

(deep to cut)

Choroid plexus

of fourth ventricle

Central canal

of spinal cord

Choroid

plexus

Interventricular

foramen

Third ventricle

Cerebral aqueduct

Lateral aperture

Fourth ventricle

Median aperture

(a) CSF circulation

CSF is produced by the

choroid plexus of each

ventricle.

1

CSF flows through the

ventricles and into the

subarachnoid space via the

median and lateral apertures.

Some CSF flows through the

central canal of the spinal cord.

2

CSF flows through the

subarachnoid space.

3

CSF is absorbed into the dural venous

sinuses via the arachnoid villi.

4

1

2

3

4Slide24

Cerebral Spinal Fluid

The brain is made up of four ventricles.

CSF is formed in these structures and flows through the CNS.Slide25

Cerebral Spinal Fluid

1

st/2nd= paired lateral ventricles (lie in cerebral hemispheres) [separated by septum pellucidum- transparent wall]Slide26

Cerebral Spinal Fluid

1

st/2nd= paired lateral ventricles (lie in cerebral hemispheres) [separated by septum pellucidum- transparent wall]3rd ventricle lies within diencephalon [connected to each lateral ventricles by interventricular foreamen]Slide27

Cerebral Spinal Fluid

1

st/2nd= paired lateral ventricles (lie in cerebral hemispheres) [separated by septum pellucidum- transparent wall]3rd ventricle lies within diencephalon [connected to each lateral ventricles by interventricular foreamen]In midbrain is central cavity => cerebral aqueduct [connects 3rd/4th ventricle]Slide28

Cerebral Spinal Fluid

1

st/2nd= paired lateral ventricles (lie in cerebral hemispheres) [separated by septum pellucidum- transparent wall]3rd ventricle lies within diencephalon [connected to each lateral ventricles by interventricular foreamen]In midbrain is central cavity => cerebral aqueduct [connects 3rd/4th ventricle]4th

ventricle lies in the brain steam, dorsal to the ponsSlide29

Cerebral Spinal FluidSlide30

Cerebral Spinal Fluid

CSF is formed in the choroid plexuses that hang is each ventricle.Slide31

Cerebral Spinal Fluid

A complication seen with the ventricle system is hydrocephalus.

This occurs when one of the aqueducts are blockedSlide32
Slide33

Blood Brain Barrier

This is a protective mechanism that helps to maintain a stable internal environment. This is to keep the neurons from firing uncontrollably when there is a slight shift in ion or water concentrations.Slide34

Blood Brain Barrier

To reach the neurons, 3 layers must be passed. These are:

The endothelium of the capillary wallThe thick basal lamina surrounding each capillaryThe “feet” or processes from the astrocytes touching the capillaries Slide35

Blood Brain Barrier

The barrier is NOT effective against nonpolar compounds such as fats or gases, this why anesthetics, alcohol and nicotine can affect the brain. Slide36

Injury to the Brain

Traumatic brain injuries are the leading cause of death in North America.Slide37

Injuries

Major cause of death and disabilities world wide.

Major population are the youngSlide38
Slide39

Injury to the Brain

Concussion which is a temporary alteration in brain function. This is typically caused by a blow to the head.

Signs and symptoms usually include dizziness and mild headache. Slide40

Concussion

A study from McGill University in Montreal found 60 percent of college soccer players reported concussion symptoms at least once during a season.

The University of Pittsburgh’s Brain Trauma Research Center estimates 34 percent of college football players have had one concussion while 20 percent have endured multiple concussions.Slide41

Concussion

Neuro

- Psychological testing is designed to test brain function and identify elements of cognitive damage and recovery that may not be discernible through self-reporting.Slide42
Slide43

Stroke or CVA

Cerebral vascular accidents or strokes are the single most common type of brain injury. This is brought about by a blockage of the arteries to the brain. Depending on where the blockage occurs, the CVA can go be mild or devastating.Slide44

Stroke

This refers to a condition of sudden onset which is due to either a blocked artery or a broken (ruptured) artery

.Slide45

Types of Strokes

Cerebral InfarctionSlide46

Types of Strokes

Cerebral Infarction

Transient Ischemic Attack (TIA)‏Slide47

Types of Strokes

Cerebral Infarction

Transient Ischemic Attack (TIA)‏

Hemorrhagic Slide48

Cerebral Infarction

This is due to a blocked or partially blocked artery in the brain. Slide49

Transient Ischemic Attack

This is due to a blocked or partially blocked artery in the brain but the symptoms resolve on their own in 24 hours. Slide50

Hemorrhagic Stroke

This is due to a broken blood vessel

.Slide51
Slide52

SymptomsSlide53

Symptoms

Dizziness

Weakness on one side

Headache

Vomiting

Seizures

Slurred speech

ConfusionSlide54