Neuro 3 - White Matter, Blood Supply, Ventricles

Association Fibers

Intrahemispheric, connecting different areas of cerebral cortex

• Superior longitudinal / acruate fasiculus

Commissural Fibers

interhemispheric, connect homologous areas of cerebral cortex

• Corpus callosum, anterior/posterior commissure

Projection fibers

connects cerebral cortex to subcortical areas, to the brainstem and spinal cord or vice versa

Dorsal and Ventral Processing Streams

important for emotional regulation and emotional behaviors

Dorsal stream

important in phonology

Ventral stream

important in semantics

Uncinate Fasiculus

connects broca’s area to anterior temporal lobe

the brain without oxygen

lose consciousness in 10 sec

irreversible brain damage in 3-5 mins

Internal carotid artery

Major blood source to the brain

• branches into anterior and middle cerebral artery

Vertebral Artery

Major blood source to brain

Fuse to form the basilar artery then branches into posterior cerebral arteries

• passes through the transverse foramen (CV)

Circle of Willis

MCA branch 1 - M1

Horizontal, Stroke here affects everything because all blood flow is blocked from the rest of the brain

MCA Branch 2 - M2

superior insular cortex

MCA Branch 3 - M3

inferior ventral surface of frontal cortex

MCA Branch 4 - M4

Cortical Surface - Lateral

• Frontal lobe (prefrontal, pre-central, central)

• Parietal lobe (Postcentral, anterior, and posterior, angular gyrus)

• Temporal lobe (polar, anterior, middle, and posterior)

Basilar - Superior cerebellar arteries

• Superior cerebellum

• dorsal pons

• midbrain

Basilar - Anterior inferior cerebellar arteries

• central core

• ventral cerebrum

Basilar - Pontine arteries

ventral pons

Vertebral - Posterior Inferior Cerebellar Artery

• inferior cerebellum

• lateral medulla

Vertebral - Anterior spinal artery

• medulla

• spinal cord

vertebral - posterior spinal artery

• spinal cord

thrombosis

blockage in the artery

embolism

part of blockage breaks off and causes another blockage later on

Infarct

necrotic tissue, due to ischemia; irreversible

• due to blood deprivation and loss of tissue perfusion

Penumbra

hypoperfused tissue - salvageable

Ischemic Stroke

Caused by a blockage in the blood flow somewhere in the brain (thrombosis or embolism)

• facial droop, arm weakness, speech difficulty, numbness

Watershed Stroke

vulnerability between territories of the cerebral arteries

• furthest from blood source and largest arterial branches

TIA - Mini stroke

Transient Ischemic Attack

• blockage (usually embolism) that resolves on its own in a few mins or hours

• Precursor to ischemic stroke

Hemorrhagic Stroke

blood is beginning to pool in areas it should not be pooling

• extreme headache, nausea, vomiting, loss of consciousness, sudden onset

Hematoma

collection of pooled blood

Hemorrhage

site of active bleeding

Epidural hematoma

below the skull but above the dura

subdural hematoma

below the dura, above the arachnoid

Subarachnoid hemorrhage

below the arachnoid, above the pia

intracerebral hemorrhage

within the cerebrum

intraventricular hemorrhage

within the ventricles

Arteriovenous Malformation (AVM)

Congenital tangles of arteries and/or veins

• may just need to be monitored

• may need surgical intervention

Cerebrospinal fluid

• Protects the CNS: absorbs shock and cushions against injury

• Reduces the perceived weight of the brain due to buoyancy

• Delivers nutrients and chemical signals (hormones) to the CNS

• Remove the metabolic waste from the CNS

Hydrocephalus

“water on the brain”

Communicating Hydrocephalus

CSF flow blocked after leaving the ventricles

Non-Communicating Hydrocephalus

CSF flow blocked in one or more passages connecting the ventricles

• aqueduct or foramina

Vacuo Hydrocephalus

Appearance of hydrocephalus due to damages, shrunken brain tissues leading to expansion of ventricles

Normal pressure hydrocephalus

Gradual change in CSF build-up allows the brain to compensate, reducing pressure increase

CSF produced in…

choroid plexus (in each ventricle)

• 16 oz per day

CSF removed through …

leaves through the sinuses to be removed through the venious system

Computed Axial Tomography (CT/CAT)

• Pros: fast, inexpensive, less sensitive to motion, good at detecting hemorrhage

• Cons: Exposure to radiation, delay in detecting ischemia

Magnetic Resonance Imaging (MRI)

• Pros: better resolution, no radiation, many possible sequences, better detection of ischemia

• Cons: longer, more sensitive to motion, metal implants contraindicated

Cerebral Angiography (CTA)

• Pros: visualization or arterial blood supply and collateral circulation, aneurysms, AVMs and tumors

• Cons: requires sedation, contrast, exposure to radiation