1. Protection and Injury to the Brain

2. Protection of the Brain
Nervous tissue is soft and easily injured. Several systems are in place to protect the brain.

3. Meninges
The Meninges consist of three connective tissue membranes that cover the organs of the CNS. They have several functions:
Cover and protect the CNS
Protect the blood vessels and venous sinuses
Contain cerebral spinal fluid
Form partitions within the skull

4. The three layers are
dura mater
arachnoid mater
pia mater
(Think DAP)

5. 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 skull
The meningeal layer is the true external covering
They can form venous sinuses and dural septa  

6. Dural septa and Dural venous sinuses.
Superior
sagittal sinus
Skull
Falx cerebri
Straight
sinus
Scalp
Occipital lobe
Crista galli
of the
ethmoid
bone
Tentorium
cerebelli
Dura mater
Falx
Transverse
sinus
cerebelli
Pituitary
gland
Cerebellum
Temporal
bone
Arachnoid
mater over
medulla
oblongata
(a) Dural septa
(b) Dural venous sinuses

7. Superior
sagittal sinus
Skull
Falx cerebri
Scalp
Occipital lobe
Tentorium
cerebelli
Dura mater
Falx
cerebelli
Transverse
sinus
Cerebellum
Temporal
bone
Arachnoid
mater over
medulla
oblongata
(b) Dural venous sinuses

8. 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.

9. 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 convolution

10. Skull
Epidural Space
Dura Mater
Subdural Space
Arachnoid
Subarachnoid space
Pia Mater

11. Skin of scalp
Periosteum
Bone of skull
Periosteal
Dura
mater
Meningeal
Superior
sagittal sinus
Arachnoid mater
Pia mater
Subdural
space
Arachnoid villus
Blood vessel
Subarachnoid
space
Falx cerebri
(in longitudinal
fissure only)

12. Conditions involving the Meninges
Meningitis is an inflammation of the meninges.
It can be, most commonly, of viral or bacterial origin
The bacterial form is potentially fatal while the viral form is self limited.

13. Signs and Symptoms Most common signs are: Headache
Nuchal rigidity (Can’t flex neck)
Altered mental status (acting strange)

14. Signs and Symptoms

15. Conditions involving the Meninges
Brain bleeds can be of three types, epidural, subdural or subarachnoid.

16. 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 trauma
Characterized by arterial blood accumulating in the epidural space
Individuals typically are lucid and then deteriorate rapidly due to bleeding from arteries.

17. 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 trauma
Characterized by venous blood accumulating in the subdural space
The onset of symptoms is gradual these include confusion and headache.

18. They can wake up dead
Epidural Hematoma
Subdural Hematoma

19. 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.

20. Conditions involving the Meninges
Sub arachnoid hematoma usually occurs as a result of a ruptured blood vessel.

21. 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.

22. Cerebral Spinal Fluid (CSF)
CSF has a makeup similar to blood plasma but has less protein.

23. Figure 12.26a Formation, location, and circulation of CSF.
Superior
sagittal sinus 4
Choroid
plexus
Arachnoid villus
Interventricular
foramen
Subarachnoid space
Arachnoid mater
Meningeal dura mater
Periosteal dura mater 1
Right lateral ventricle
(deep to cut)
Choroid plexus
of fourth ventricle 3
Third ventricle
CSF is produced by the
choroid plexus of each
ventricle. 1
Cerebral aqueduct
Lateral aperture
Fourth ventricle
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
Median aperture 2
Central canal
of spinal cord
CSF flows through the
subarachnoid space. 3
(a) CSF circulation
CSF is absorbed into the dural venous
sinuses via the arachnoid villi. 4

24. Cerebral Spinal Fluid
The brain is made up of four ventricles. CSF is formed in these structures and flows through the CNS.

25. Cerebral Spinal Fluid
1st/2nd= paired lateral ventricles (lie in cerebral hemispheres) [separated by septum pellucidum- transparent wall]

26. Cerebral Spinal Fluid
1st/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]

27. Cerebral Spinal Fluid
1st/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]

28. Cerebral Spinal Fluid
1st/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 pons

29. Cerebral Spinal Fluid

30. Cerebral Spinal Fluid
CSF is formed in the choroid plexuses that hang is each ventricle.

31. Cerebral Spinal Fluid
A complication seen with the ventricle system is hydrocephalus.
This occurs when one of the aqueducts are blocked

33. 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.

34. To reach the neurons, 3 layers must be passed. These are:
Blood Brain Barrier
To reach the neurons, 3 layers must be passed. These are:
The endothelium of the capillary wall
The thick basal lamina surrounding each capillary
The “feet” or processes from the astrocytes touching the capillaries

35. 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.

36. Injury to the Brain
Traumatic brain injuries are the leading cause of death in North America.

37. Injuries Major cause of death and disabilities world wide.
Major population are the young

39. 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.

40. 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.

41. 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.

43. 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.

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

45. Types of Strokes
Cerebral Infarction

46. Types of Strokes
Cerebral Infarction
Transient Ischemic Attack (TIA)‏

47. Types of Strokes Cerebral Infarction Transient Ischemic Attack (TIA)‏
Hemorrhagic

48. Cerebral Infarction
This is due to a blocked or partially blocked artery in the brain.

49. 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.

50. This is due to a broken blood vessel.
Hemorrhagic Stroke
This is due to a broken blood vessel.

51. Symptoms

52. Symptoms Dizziness Weakness on one side Headache Vomiting Seizures
Slurred speech
Confusion