Brain structur es (Internal & External)
Dec 30, 2015
Brain structures(Internal & External)
1. BLOOD SUPPLYMajor ARTERIES of the Head and Neck
STROKE: Interruption in blood supply to parts of the brain
lead to death of neural tissue. Can be caused by a clot
(ischemic) or an injury (hemorrhagic).
DURAL SINUSES: Chambers that receive blood from veins and CSF from meninges.
Major VEINS of the Head and Neck
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2. THE MENINGES
• Dura mater: Hard, tough tissue in contact with the skull. In parts it splits into two layers forming the dural sinuses.
• Arachnoid: Middle layer containing collagen fibers.
Subarachnoid space (between arachnoid & pia mater) is
full of CSF. protects and cushions the brain and is
involved in waste & nutrient exchange.
• Pia mater: Thin layer fused to the brain itself. Contains all the main blood vessels.
Meninges (from out to in)
• Note: The subdural space between the dura mater and arachnoid only forms following trauma, injury or death through fluid loss. Normally the dura mater and arachnoid are in contact with each other.
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The Meninges
Figure 8-13(a)
Meningitis(Viral & Bacterial)
Inflammation of the brain meninges. Because infection
occurs so close to the brain it is considered a medical
emergency.
SPINA BIFIDAA malformation of the meninges.
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Vertebrae overlying spinal cord not fully formed and remain unfused and open. If the opening is large enough a portion of meninges and spinal cord may protrude, sometimes without a fluid-filled sac. A cyst forms.
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Meningomyelocele: Meninges & spinal cord protrude. Meningocele: Only meninges protrude.
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3. HEMISPHERES & LOBES Right & left hemispheres bridged by the Corpus
Callosum, a bundle of axons involved in data transfer.
• Four main lobes in both hemispheres: Frontal, Parietal, Temporal & Occipital.
Speech
Occipital lobe
Vision
Temporal lobe
Frontal lobeParietal lobe
Somatosensoryassociationarea
Frontalassociationarea
Visualassociationarea
Reading
Taste
Hearing(Wernicke’s area)
Auditoryassociationarea
Motor Speech (Broca’s area)
Smell
Mo
tor
cort
exS
omat
osen
sory
cor
tex
• Sulci: the grooves found on the brain’s surface (sing: sulcus)
• Central sulcus separates frontal and parietal lobes, Lateral sulcus separates frontal & parietal lobes from temporal lobe.
What is a LOBOTOMY?
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4. THE VENTRICLES & CSF• 4 cavities located in the CNS, all
connected by channels and filled with cerebrospinal fluid (CSF).
CSF produced in the choroid plexus; cushions and supports the brain, transports nutrients and waste.
CSF can leak into the blood located in the dural sinuses through the arachnoid granulations.
Blood infections can reach the brain through this route!
SPINAL TAPA sample of CSF taken from the spinal cord will reveal any
infections, chemical inbalances or brain afflictions.
5. Grey & White Matter
Axon Myelin sheath
Schwanncell
Nodes ofRanvier
Schwanncell
Nucleus ofSchwann cell
Node of Ranvier
Layers of myelinAxon
Whiteness due to the lipids in the myelin sheath.