This document provides an overview of brain anatomy and physiology. It describes the major structures of the brain including the meninges, lobes, gyri and sulci. It outlines the circulation of cerebrospinal fluid and blood supply to the brain. The document also reviews the cranial nerves and brainstem, detailing the origin and function of each cranial nerve.

1. Brain Anatomy and
Physiology
Dr. Nevo Margalit – Neurosurgery
Tel Aviv Sourasky Medical Center

2. Scalp
• Skin
• Connective tissue (superficial fascia)
• Epicranial aponeurosis (galea
aponeurotica)
• Loose areolar tissue
• Pericranium
• Occipitofrontalis muscle

3. Scalp

4. The Skull

5. The Skull

6. The skull

7. The Menings
The 3 layers covering the brain
• Dura: covers the brain and spinal cord. The
venous sinuses run through the dura. 2
additional Parts of the dura are the Tentorium
and the Falx Cerebri.
• Arachnoid: Transparent, thin web structure.
Creates a space around the brain called the
sub arachnoid space where the CSF and the
main blood vessels pass.
• Pia: a very thin layer. Coats the brain and
spinal cord and is inseparable from them.

8. Dura

10. Tentorium and Falx

11. Tentorium

12. Arachnoid

13. Arachnoid – Basal Cisterns

14. Parts of the Central Nervous
System
• 2 hemispheres
• Brainstem
• Cerebellum
• Spinal cord

15. Each hemisphere has lobes:
• Frontal lobe
• Parietal lobe
• Temporal lobe
• Occipital lobe
• Insular lobe
• Limbic lobe

16. Lateral View

17. Insula

20. Gyruses and sulci
• Each lobe is composed of gyruses
separated by sulci
• The topography can be defined by
histology, anatomical relationships or
function

21. Map Brodmann

22. Gyruses and Sulci

23. Functional areas

24. Function 2

25. Function 3

26. f-MRI

27. The Motor Strip

28. Fibers

29. Ventricles and CSF

30. Ventricles and CSF
• CSF is produced by the choroid plexus
in the ventricles
• The circulation is from the lateral
ventricles to the third through the
Monroe- aqueduct- IV ventricle- sub
arachnoid space in skull and spine-
absorption in sss and other sinuses
through arachnoid granulations

31. CSF Pathways

32. CSF Pathways

33. Arteries of the brain

34. Arteries of the brain
• Anterior circulation – internal
carotid artery, from common
carotid in the neck. Bifurcates to
MCA and ACA
• Posterior circulation – vertebral
arteries that join to form the basilar
artery that will then bifurcate to 2
PCA

35. Circle of Willis
• Communication between 2 sides –
anterior communicating (a-com)
• Communication between anterior
and posterior circulation – posterior
communicating (p-com)
• Many anomalies may exist

36. Arteries in the neck

37. Arteries in the subarachnoid
space

38. Arteries of the brain

39. Physiology

40. Blood supply to the brain
• The brain gets 15% of the cardiac output
and 20% of the oxygen consumption
• The brain tissue gets in average 50ml of
blood per 100gr of tissue per minute. The
gray matter receives about 3 to 4 times
more then the white matter
• Total blood supply to the brain is about 500-
600ml per minute

41. Factors Affecting the blood
supply
• Autoregulation
• Biochemical changes – O2 and CO2
• Blood brain barrier - BBB

42. Autoregulation
• Maintains a regular blood supply to the
brain in changing blood pressures
• The range is 50-130 mm mercury
• Possible mechanisms are the
myogenic control, neurogenic and
biochemichal control

43. CO2
• The most important and powerful
mechanism that controls brain blood
flow
• A change in 1mm PCO2 changes the
flow in 4-5%
• PCO2 of 70 gives a maximal
vasodilatation. Above that the flow is
pressure dependent

44. Hyperventilation
• Hyperventilation lowers the PCO2
• It has a strong effect but it is limited in
time
• Could be dangerous if not regulated-
ischemia
• Can be regulated with a jugular bulb
oximeter

45. BLOOD BRAIN BARRIER
• The BBB is composed of the tight
junctions in the endothelium cells of
the blood vessels
• Prevents passage of large molecules
and even small ions like Na and Cl
• Specific substances pass the BBB like
glucose and amino acids

46. BLOOD BRAIN BARRIER
• Because of the BBB, in the brain
hydrostatic and oncotic pressures are
not significant. The important
parameter is the osmotic pressure
• The BBB is damages in trauma, tumor,
infarct, SAH and infection

47. BLOOD BRAIN BARRIER

48. Brainstem and Cranial Nerves

49. Brain stem
• Has 3 parts: midbrain, pons and medulla
• Transports all the information to and from
the brain
• Centers for breathing and blood pressure
• The origin or endpoint for cranial nerves
• Contains the center of consciousness
• Creates connections to the cerebellum

53. Nuclei in the brain stem

55. Cranial nerves
• 12 pairs of nerves
• All cranial nerves except I and II
originate from the brainstem
• The nerves are sensory, motor or
mixed
• There are nuclei in the brainstem that
are the origin or the endpoint of the
cranial nerves

56. CN 1- Olfactory Nerve
• The sensation of smell
• Pure sensory nerve
• From the nose to the forebrain
• Very developed in some animals
• Tested an odorous substance

60. CN 2 - Optic N
• Visual information from the eye to the
brain
• Pure sensory nerve
• Belongs to the CNS and is not part of
the PNS
• Problems could result in field problem,
acuity problem and more
• Tested with a vision chart and field
exam on confrontation

64. CN 3, 4, 6- occulomotor, trochlear
and abbducence
• Nerves that control the movement of the
eyes and the constriction of the pupil
• Pure motor nerves
• Problems result in unsynchronized eye
movements and/ or dilated pupil
• Tested with the patient following a finger
and with light

68. CN 5 – Trigeminal N
• The largest CN
• Sensory and motor
• Sensation from the face eyes, mouth,
and motor for mastication muscles
• Tested with touch and pin on face

71. CN 7 – Facial N
• Motor nerve of the face and taste from
the tongue
• Motor and sensory
• Tested with movement of the facial
muscles

76. CN 8 – Vestibulocochlear N
• The nerves for hearing and balance
• Sensory nerves
• The most common origin of a
schwanoma
• Tested by hearing test and balance
function

79. CN 9 – Glossopharyngeal N
• Sensation from the pharynx
• Mainly sensory and small motor part
• Problems result in aspiration
• Tested with the gag reflex

81. CN 10 – Vagus N
• Motor to the muscles larynx and
pharynx and the parasympathetic of
the body
• Motor nerve
• Problems result in hoarseness
• Tested by opening mouth wide and
saying “AH“

83. CN 11 – Accessory N
• Nerve to the trapezius and
sternomastoid muscles
• Motor nerve
• Tested with shoulder raise or turning
the head

85. CN 12 – Hypoglossal N
• Nerve to the muscle of the tongue
• Motor nerve
• Tested with movement of the tongue