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brain anatomy neuroanatomy medical physiology neurology

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This document is a lecture on brain anatomy and physiology. It covers topics such as meninges, trauma, ventricles, choroid, CSF, hydrocephalus, cisterns, and more.

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Lecture 020425 Meninges Trauma – Hemorrhage – Herniation – Case Study 1 Ventricles, Choroid, CSF Hydrocephalus Cisterns Readings: Ch 6, 7 – Case Study 2 dura mater Meningeal layers closely apposed to...

Lecture 020425 Meninges Trauma – Hemorrhage – Herniation – Case Study 1 Ventricles, Choroid, CSF Hydrocephalus Cisterns Readings: Ch 6, 7 – Case Study 2 dura mater Meningeal layers closely apposed to skull inner layer forms sinuses arachnoid mater cerebrospinal fluid (CSF) flows in subarachnoid space subarachnoid space does not follow sulci arachnoid trabeculae - support pia mater closely apposed to brain parenchyma pia + arachnoid = leptomeninges Meningeal layers of brain Meningeal layers of spinal cord skull – closely apposed to dura spinal column – separated by epidural space falx cerebri tentorium cerebelli Periosteal dural infoldings falx cerebri - midline shift* tentorium cerebelli - transtentorial herniation* falx cerebelli - diaphragma sella - covers hypophyseal fossa (thus, pituitary tumors can compress hypothalamus) *See slide 11 for types of brain herniation* diaphragma sella falx cerebelli Relation of meninges to flow of CSF 1. brain - dura apposed to skull arachnoid trabeculae – support arachnoid villi (granulations) - venous return of CSF into superior sagittal sinus sub-arachnoid space accessible in cisterna magnum 2. spinal column - dura away from vertebrae denticulate ligaments - support within cord sub-arachnoid space accessible in lumbar cistern Lumbar puncture to obtain CSF Meningitis: brain or spinal cord inflammation General Signs of Meningeal Irritation: Nuchal Rigidity Headache Fever What sign of inflammation? Long-term consequences of meningitis: Meningitis: bacterial, viral fungal or environmental (trauma, medications) origin cranial nerve palsies II, VII, VIII general paresis CSF samples to identify source of meningitis sensory loss and ataxia Brudzinski’s sign - neck flexion by practitioner Specific Signs of causes hip flexion in patient Meningeal Irritation: Kernig’s sign - knee straighten by practitioner Uhh. Owie.. causes hamstring pain in patient http://www.nytimes.com/imagepages/2007/08/01/health/ada http://www.yourhealthconnection.com/Imagebank/adam/19069.jpg Head trauma - damage to brain coup and counter coup injuries concussion - alteration of consciousness contusion - brain tissue injury hemorrhagic lesions, axonal injury post traumatic head injury: hydrocephalus dementia Contusions: displaced skull fracture temporal > skull thickness inferior frontal coup/countercoup occipital Vascular injury - hematoma Epi-dural hematoma: skull fracture tearing of meningeal arteries typical Sub-dural hematoma: concussion / contusions typically, tearing of veins at the dural / meningeal border Sub-ararchnoid hemorrhage: typically, ruptured aneurysm of arteries, into the subarachnoid space epidural hematoma subdural hematoma subarachnoid hemorrhage (next slide) contusion - damage at surface of brain intra-parenchymal hemorrhage - within brain tissue Subarachnoid paracallosal quadrigeminal cisterns lamina terminalis chiasmatic ambient interpeduncular (fossa) prepontine premedullary * cisterna magna * lumbar cistern } CSF samples cisterns collect fluid in areas of cranial nerves, arteries and veins *Cisterns are useful in imaging to blood in CSF - injury can be visualized by contrast detect sub-arachnoid hemorrhage* Autopsy and CT scans of hematoma Subdural Epidural CT scans, hematoma MRI scans, meningioma Contusion Subarachnoid Meningeal tumors (right) pressure against parenchyma pressure on brainstem malignancy Intra-parenchymal Herniation - displacement diffuse cerebral edema parenchymal tumor of brain parenchyma liquefactive abcess hemorrhage 1. midline shift subfalcine herniation cingulate gyrus under falx cerebri increased intracranial pressure 2. transtentorial uncal herniation temporal lobe against tentorium damage to CN III, cerebral peduncles Duret hemorrhage eyemotor palsy hemiparesis. 3. tonsillar herniation cerebellum through foramen magnum pressure on medulla of brainstem cardiac distress subdural hematoma respiratory distress and midline shift Case Study One. 52 year old male Headaches. Increasing left sided weakness. Increasing lethargy. MRI reveals R side tumor; Downward herniation / transtentorial glioblastoma multiforme. Passed away, family requests autopsy. Confirm tumor mass R side. Uncal herniation can affect: Multiple structures at tentorial notch. Autopsy results, next slide. Brain autopsy, inferior Sections on autopsy, coronal This case patient symptoms: lethargy - reticular formation weakness - cerebral peduncle Also observed: Duret hemorrhage posterior cerebral artery infarction CN III compression Development of ventricles and communicating spaces within CNS Vesicles are brain regions 3 vesicle stage One space At 5 vesicle stage Expansion and flexures: Telencephalon: lateral ventricles cerebrum Diencephalon: third ventricle thalamus Mesencephalon: cerebral aqueduct midbrain pons, cerebellum Metencephalon and myelencephalon: fourth ventricle medulla spinal cord Spinal cord: central canal lateral ventricles Ventricles and communicating spaces anterior horn inferior horn atrium posterior horn foramen of Monro (interventricular foramen) third ventricle cerebral aqueduct of Sylvius fourth ventricle foramen of Magendie foramina of Luschka “Number 1, meet me in the posterior horn And bring that big fellow along too.” central canal Choroid plexus - production of CSF lateral ventricle fourth ventricle circulation of CSF ventricular exits foramen of Magendie foramina of Luschka Distribution of ventricles / choroid lateral ventricles in cerebrum third ventricle in diencephalon cerebral aqueduct in midbrain fourth ventricle above medulla T1 and T2 MRI - ventricles I, II Production and flow of cerebrospinal fluid CSF produced: choroid capillary tufts (plexus) - lateral and fourth ventricles functions in buoyancy and shock absorption CSF flows: Arachnoid villus a. ventricular system, into central canal, and out foramina of Magendie / Luschka b. throughout subarachnoid space CSF returns: through arachnoid granulations (villi) into superior sagittal sinus This fluid (in the blood) returns to right side of heart, vena cava Ependyma epithelial lining of ventricular cavity tanycyte end feet contact blood vessels help in ventricle / blood barrier ependymoma - childhood tumor ventricle consequences include: hydrocephalus and / or compression of brainstem - cranial nerve dysfunction Hydrocephalus 1 1. Developmental disorder aqueductal obstructive stenosis CSF production / resorption enlargement of cranium 2. Hydrocephalus ex vacuo loss of parenchyma (Huntington’s) enlargement of the lateral ventricles 3. Adult obstructive hydrocephalus convulsions, seizures 2 3 4. Pseudotumor cerebri hypertensive disease, diabetes 5. Normal Pressure hydrocephalus more common in women remitting increase in intracranial pressure headaches and nausea symptoms: gait imbalance, incontinence, dementia Pathologies affecting intracranial pressure Consequences Hydrocephalus compression of vasculature, hemorrhage Hematoma compression of parenchyma, edema Tumors Infection Obesity, diabetes Presentation: posterior scalp laceration, lethargy, decreased level of consciousness Case study 2 - onset and recovery from contusion right hemi-plegia and sensory loss absent right corneal reflex coup/countercoup cerebral contusion subdural hematoma midline shift midline shift midline shift pineal calcification subdural and subarachnoid hematoma falx cerebri and tentorium cerebelli Reactive gliosis Follow Up: Pineal and choroid calcification Hydrocephalus ex vacuo Countercoup injury affected frontal and temporal lobes. Lethargy and level of consciousness resolved in time. Hemiparesis from compression of corticospinal tract also resolved over the course of approximately one year. Corneal reflex dysfunction also suggested that brainstem (tentorium) was involved. Summary of vascular system - arterial blood fluid exchange brain to blood blood brain barrier blood CSF barrier interstitial tissue CSF in ventricles intracellular cytoplasm and subarachnoid space of neurons and glia cerebral venules arachnoid villi cerebral veins venous sinuses superior sagittal sinus spinal sinuses

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