Meninges and Cerebrospinal Fluid PDF

Meninges and cerebrospinal fluid Dura mater Dural layers are fused EXCEPT in dural sinuses (seno venoso es una vena metida dentro de la dura) Cranial Epidural Space Potential Space Septa Compartmentalize the cranial cavity; Reduces or prevent displacement +-----------------------+--------------...

Meninges and cerebrospinal fluid Dura mater Dural layers are fused EXCEPT in dural sinuses (seno venoso es una vena metida dentro de la dura) Cranial Epidural Space Potential Space Septa Compartmentalize the cranial cavity; Reduces or prevent displacement +-----------------------+-----------------------+-----------------------+ | Tough, fibrous | A diagram of a human | | | membrane | body Description | | | | automatically | | | | generated | | +=======================+=======================+=======================+ | Periosteal layer | Highly vascular and | | | | innervated | | +-----------------------+-----------------------+-----------------------+ | | ONLY in the cranial | | | | cavity ( no va al | | | | cordon espinal) | | +-----------------------+-----------------------+-----------------------+ | Meningeal layer | Smooth and avascular | | +-----------------------+-----------------------+-----------------------+ | | Continuous with | | | | spinal dura | | +-----------------------+-----------------------+-----------------------+ | Falx cerebri | Septo de la dura que |  | | | | | | | Separa los dos | | | | hemisferios | | +-----------------------+-----------------------+-----------------------+ | Tentorium cerebelli | Separa el lobuo | | | | occipital del | | | | cerebelo | | +-----------------------+-----------------------+-----------------------+ | Falx cerebelli | Separa hemisferios | | | | del cerebelo | | +-----------------------+-----------------------+-----------------------+ | Meningeal arteries | | | | | | | | La arteria que suple | | | | la dura es la middle | | | | meningeal artery | | | +-----------------------+-----------------------+-----------------------+ Arachnoid mater Delicate, avascular membrane between the dura and pia matter -------------------------------------------------------------- --------------------------------------------------- ------------------------------------------------------------------------------------ Loosley attached to the dura Gross: looks like " cling-wrap (GLAD) Arachnoid villi Projections of arachnoid that pierce the dura  Protrude into the venous sinuses Allow CSF to flow into the sinuses One-way valves Arachnoid granulations Clusters of arachnoid villi Granular foveola Impressions of arachnoid granulations in calvaria  Subarachnoid space +-----------------+-----------------+-----------------+-----------------+ | Space between | A diagram of a | | | | pia and | human body | | | | arachnoid mater | Description | | | | | automatically | | | | | generated | | | +=================+=================+=================+=================+ | Filled with CSF | | | | +-----------------+-----------------+-----------------+-----------------+ | Subarachnoid | 200 mm H2O | | | | space | | | | +-----------------+-----------------+-----------------+-----------------+ | Dural sinuses | 80 mm H20 | | | +-----------------+-----------------+-----------------+-----------------+ | Arachnoid | Collagen fibers | | | | trabeculae | that connects | | | | | arachnoid with | | | | | pia mater | | | | | | | | | | Keep brain | | | | | suspended | | | +-----------------+-----------------+-----------------+-----------------+ | Subarachnoid | Enlargement of | | | | cisterns | subarachnoid | | | | | space | | | +-----------------+-----------------+-----------------+-----------------+ | | Cerebellomedull | Large cistern | | | | ary | between the | | | | cistern | medulla and | | | | (cisterna magna | cerebellum | | +-----------------+-----------------+-----------------+-----------------+ | | Important to | | | | | identify | | | | | pathological | | | | | process | | | +-----------------+-----------------+-----------------+-----------------+ Pia mater Vascular membrane tightly apposed to the surface of brain and spinal cord A diagram of the spine Description automatically generated --------------------------------------------------------------------------- ------------------------------------------------------------ -- Denticulate ligament Anchor the Spinal cord to the dura mater (ancla lateral) Filum terminale Terminal end of spinal cord (ancla la parte inferior) Spinal cord vs Brain Spinal dura Meningeal layer only  ----------------------- ------------------------------------------------------------------------------------------------------- ------------------------------------------------------------------------------------ Ends at S2 Spinal epidural space Actual space in which venous plesxuses and fatty tissue are located Used clinically for the administration of epidural anesthesia to produce a para vertebral nerve block Lumbar cistern and lumbar puncture/ spinal tap Info about the cellular and chemical composition of the CSF in disorders  -------------------------------------------------------------------------- --------------------------------------------------------------------------------------------- ---------------- -- 5-15 ml CSF CSF pressure Adult 100-150 mm H2O Infant and children 60-150 mm H2O Warning: If increase ICP, withdrawal of CSF is contraindicated Brain herniation through foramen magnum Disorders associated with meninges +-----------------------+-----------------------+-----------------------+ | Meningitis | Infection of meninges | | +=======================+=======================+=======================+ | Causes | Bacterial, viral or | | | | fungal infection | | +-----------------------+-----------------------+-----------------------+ | Symptoms: | Headache... | | | | | | | | Stiff neck , seizures | | | | (1/3pts) due to | | | | increase | | +-----------------------+-----------------------+-----------------------+ | CSF: | cloudy, increase | | | | protein, White blood | | +-----------------------+-----------------------+-----------------------+ +-----------------------+-----------------------+-----------------------+ | Meningioma | Tumors arising from |  | | | en la dura) | | +=======================+=======================+=======================+ | Benign/ malignant | | | +-----------------------+-----------------------+-----------------------+ | Cause | Unknown | | | | | | | | Trend of | | | | abnormalities in | | | | chromosome 22 | | +-----------------------+-----------------------+-----------------------+ | Treatment | Surgical removal or | | | | radiosurgery | | +-----------------------+-----------------------+-----------------------+ +-----------------------+-----------------------+-----------------------+ | Hematoma | | | +=======================+=======================+=======================+ | Usually consequences | | | | of trauma | | | +-----------------------+-----------------------+-----------------------+ | Bleeding into | Epidural | | | potential spaces | | | | between meninges can | Subdural | | | cause separation of | | | | meningeal layers | | | +-----------------------+-----------------------+-----------------------+ | Can be life | Neural tissue is | | | threatening | compressed and | | | | displaced | | +-----------------------+-----------------------+-----------------------+ Epidural hematoma Bleeding in epidural space  ----------------------------------------------------------------------------------------------- ---------------------------- --------------------------------------------------------------------------------- Often occurs when middle meningeal artery is torn by a fracture (temporal/parietal bones) Lucid interval Worsening headache, vomiting, disorientation, lethargy, decreasing consciousness, hemiparesis Subdural hematoma Bleeding in subdural space A close-up of a brain Description automatically generated -------------------------------------------------------------------------------------------------- ---------------------------- ----------------------------------------------------------- Venous bleeding Gradually worsen (dm) Sign and symptoms are similar to those to epidural hematoma, with confusion being more prominent Elderly + alcoholics +-----------------------+-----------------------+-----------------------+ | Subarachnoid |  | | +=======================+=======================+=======================+ | Cause | Rupture of an | | | | intracranial aneurysm | | +-----------------------+-----------------------+-----------------------+ | Symptoms | Intense headache | | | | | | | | Nausea | | | | | | | | Vomiting | | | | | | | | Unconsciousness | | +-----------------------+-----------------------+-----------------------+ Brain ventricular system +-----------------------+-----------------------+-----------------------+ | Lateral ventricle | 2 ventriculos | | | | | | | | Tiene horns | | +=======================+=======================+=======================+ | | **Above:** Corpus | | | | Callosum | | +-----------------------+-----------------------+-----------------------+ | | **Outside wall:** | | | | Head of caudate | | | | nucleus | | +-----------------------+-----------------------+-----------------------+ | | **Inferior Horn:** | | | | Tail of the caudate | | | | nucleus | | +-----------------------+-----------------------+-----------------------+ | | **Body:** Thalamus | | +-----------------------+-----------------------+-----------------------+ | Interventricular | Conexion entre en | | | foramina \[of Monro\] | ventriculos | | | (2) | | | | | Conecta lateral y | | | | tercer ventriculo | | | | | | | | Hay 2 | | +-----------------------+-----------------------+-----------------------+ | Third ventricle | En el midbrain | | | | diencephalon | | +-----------------------+-----------------------+-----------------------+ | | **Walls:** thalamus & | | | | hypothalamus | | +-----------------------+-----------------------+-----------------------+ | **Cerebral Aqueduct | En el midbrain entre | | | (Aqueduct of | pons, medulla y | | | Sylvius)** | cerebelo | | | | | | | | Conecta el 3er y 4to | | | | ventriculo | | +-----------------------+-----------------------+-----------------------+ | Fourth ventricle | Entre pons, medulla y | | | | cerebelo | | +-----------------------+-----------------------+-----------------------+ | **Lateral Foramina | Conecta 4to | | | \[*of Luschka | ventriculo con | | | (2)*\]** | espacio subaracnoideo | | | | | | | **Medial Foramina | Lateral lushchka | | | \[*of Magendie | | | | (1)*\]** | Medial Magendie | | +-----------------------+-----------------------+-----------------------+ Quien conecta ventriculus laterales ? +-----------------------+-----------------------+-----------------------+ | Corpus callosum |  | | +=======================+=======================+=======================+ | Lateral ventricle | Hay 2 | | | | | | | | Uno en cada | | | | hemisferio | | +-----------------------+-----------------------+-----------------------+ | Septum pellucidum | Divide ventriculus | | | | laterales y forma la | | | | pared medial | | +-----------------------+-----------------------+-----------------------+ | Caudate nucleus | Cabeza del nucleus | | | | caudado | | +-----------------------+-----------------------+-----------------------+ | Third ventricles | | | +-----------------------+-----------------------+-----------------------+ A close-up of a human brain Description automatically generated Cerebrospinal fluid Clear fluid formed by choroid plexus ( in each ventricle)  ------------------------------------------------------------------- -------------------------------------------------------------------------------------- -- Circulates through the ventricles and into the subarachnoid space Absorbed into the venous circulation Functions Buoyant effect Cuchioning effect Remove CNS metabolites Stable ionic environment Formation of CSF: Choroid plexus +-----------------------+-----------------------+-----------------------+ | Produces \~ 70% CSF | Other 30% secreted by | | | | the brain's | | | | parenchyma | | +=======================+=======================+=======================+ | Active transport | In Na+ and Mg2+ | | | mechanism | | | | | Out K+ and Ca2+ | | +-----------------------+-----------------------+-----------------------+ | Formation rate | 500 mL/day | | +-----------------------+-----------------------+-----------------------+ | Total volume: | 90-150ml (23ml on | | | | ventricles) | | +-----------------------+-----------------------+-----------------------+ Circulation of CSF Unidirectional flow; pulsatile Lateral ventricles Interventricular foramina Third ventricle Cerebral aqueduct Fourth ventricle Lateral and medial foramina Subarachnoid space (1^st^ =cisterna magna) Arachnoid villi Dural venous sinuses CSF parecido al plasma - No RBCs, sterile and low protein CSF menor cantidad de concentracion de: - Proteina - Glucose - Ca2+ - K+ CSF mayor concentracaion de: - Na+ - Cl- - Mg2+ Pathological conditions Generalidades - en todos los niveles d eproteinas suben - glucose normal en todos except en tubercular meningitis y bacterial meningitis - hemorragia -RBCs - guillan barre syndrome (autoinmune ataca scwann cells) pocos WBCs +-----------------------------------+-----------------------------------+ | Subarachnoid hemorrhage | Xanthocromia (CSF yellow) | | | | | Presencia de RBCs | La hemoglobina se convierte en | | | Amarillo por la bilirubina | +===================================+===================================+ | Bacterial meningititis | Mas globulos blancos | | | | | | Mas de 5 lymphocytes/ul | +-----------------------------------+-----------------------------------+ | Multiple sclerosis and chronic | Increase gamma globulin levels | | infections | | +-----------------------------------+-----------------------------------+ | Acute bacterial and fungal | Decrease glucose levels | | infections | | +-----------------------------------+-----------------------------------+ Blood brain barrier +-----------------------+-----------------------+-----------------------+ | Specialized |  | | | between capillary | | | | wall and bain tissue | | | +=======================+=======================+=======================+ | Prevents the passage | | | | of large molecules | | | | from the blood into | | | | the extracellular | | | | space between the | | | | neurons and glia | | | +-----------------------+-----------------------+-----------------------+ | **Advantage** | Prevents many | | | | pathogens from | | | | entering the CNS | | +-----------------------+-----------------------+-----------------------+ | **Drawback** | Prevents certain | | | | drugs and protein | | | | antibodies to access | | | | the brain (e.g., | | | | dopamine & Parkinson | | | | disease) | | +-----------------------+-----------------------+-----------------------+ | Components | **Endothelial cells | | | | lining the capillary | | | | wall & brain tissue** | | +-----------------------+-----------------------+-----------------------+ | | **Process of | | | | astrocytes | | | | (end-feet)** | | +-----------------------+-----------------------+-----------------------+ | | **Capillary basement | | | | membrane** | | +-----------------------+-----------------------+-----------------------+ Blood -- CSF Barrier Capillary endothelium of choroid plexus is fenestrated Small molecules can pass from blood through the capillary wall  ----------------------------------------------------------------------- ---------------------------------------------------------------- ------------------------ Tight junctions exist between choroid outer layer of epithelial cells Prevent large molecules to enter into the CNS from the blood Circumventricular organs -- ALREDEDOR DE LOS VENTRICULOS 7 estructuras que no tienen la blood brain barrier Regiones por donde se puede filtrar - *It is believed that some circulating hormones consisting of large molecules reach their target areas in the brain via **circumventricular organs*** +-----------------------------------+-----------------------------------+ | AREA POSTREMA | Cerca de la medulla | | | | | | Detecta toxinas y estimula los | | | sistemas para que ocurra vomito | | | | | | **Chemotactic Trigger Zone** | | | detects circulating toxins that | | | cause vomiting | +===================================+===================================+ | Pineal gland | Libera la melatonia | | | | | | Circadian rhythms | +-----------------------------------+-----------------------------------+ | Subcommissural organ | Desarrollo del cuerpo | | | | | | Remover desechos | | | | | | Development; Waste clearance from | | | CSF | +-----------------------------------+-----------------------------------+ | Subfornical organ | Regulation of fluid balance & | | | cardiovascular homeostasis | +-----------------------------------+-----------------------------------+ | Organum vasculosum lamina | Funciones Neuroendocrine | | terminalis | | | | | | OVLT | | +-----------------------------------+-----------------------------------+ | Neurohypophysis (pituitaria | Vasopressin Oxytocin | | posterior) | | | | Hormona antidiuretica | +-----------------------------------+-----------------------------------+ | Median eminence | Interface between neural & | | | endocrine system | +-----------------------------------+-----------------------------------+ A diagram of a brain Description automatically generated Disorders of the CSF system Hydrocephalus +-----------------------+-----------------------+-----------------------+ | Ventricles | | | | enlargement; CSF | | | | blocked causing | | | | increase ICP | | | +=======================+=======================+=======================+ | Infant | Cranial bones haven't | Pressure causes | | | yet fused | ventricles, | | | | | | | | hemispheres & cranium | | | | to expand | +-----------------------+-----------------------+-----------------------+ | | Signs | disproportionately | | | | large head, large | | | | anterior fontanel, | | | | poor feeding, | | | | inactivity, and | | | | downward gaze of the | | | | eyes (compression of | | | | CN III oculomotor) | +-----------------------+-----------------------+-----------------------+ | | Common causes | Failure of the | | | | fourth ventricle | | | | foramina to open | | | | | | | | Blockage of | | | | cerebral aqueduct | | | | | | | | Cyst in the fourth | | | | ventricle | | | | | | | | Arnold-Chiari | | | | Malformation | | | | | | | | \- Downward | | | | displacement of the | | | | cerebellum through | | | | the foramen magnum | +-----------------------+-----------------------+-----------------------+ | **Older Children or | **Cranium CANNOT | Excessive pressure in | | Adults** | expand** | the ventricles | | | | compress the NS, | | | | particularly white | | | | matter | +-----------------------+-----------------------+-----------------------+ | | Commonly results in | | | | gait & balance | | | | impairments, | | | | incontinence, and | | | | headache | | +-----------------------+-----------------------+-----------------------+ | | **Frequently, frontal | | | | lobe functions are | | | | involved** | | +-----------------------+-----------------------+-----------------------+ | Non- communicating | **When movement of | | | | CSF is blocked along | | | | one or more | | | | ventricular | | | | connections** | | +-----------------------+-----------------------+-----------------------+ | Communicating | **When movement of | | | | the CSF is impeded or | | | | blocked by | | | | obstruction at | | | | arachnoid villi** | | +-----------------------+-----------------------+-----------------------+ Increased intracranial pressure (ICP) +-----------------------+-----------------------+-----------------------+ | Increase volume brain | Diffuse cerebral | | | tissue by | edema | | | | | | | | Intracerebral | | | | hemorrhage | | | | | | | | Tumor | | +=======================+=======================+=======================+ | Increase CSF volume | Obstruction of CSF | | | | flow | | +-----------------------+-----------------------+-----------------------+ | Increase blood volume | Venous obstruction | | | in the brain tissue | | | +-----------------------+-----------------------+-----------------------+ | Symptoms | Headache, Nausea, | | | | Vomiting, | | | | Bradycardia, ⇧BP, | | | | Loss of | | | | Consciousness, and | | | | Papilledema | | | | (*elevation & | | | | blurring of the optic | | | | disk margin)* | | +-----------------------+-----------------------+-----------------------+ | | | | +-----------------------+-----------------------+-----------------------+