8 - Vasculature Flashcards
Three Meningeal Layers
Dura
Arachnoid
Pia
Dura Mater
Thick, tough collagenous membrane.
Adheres to inner surface of skull AND the arachnoid mater
Contains sinuses for venous blood flow
Arachnoid Mater
Thin membrane of cells interspersed with bundles of collagen.
Arteries extend and CSF flows in the space between the Arachnoid and Pia (Subarachnoid Space)
How does CSF enter venous circulation?
Passively (down a pressure gradient) via Arachnoic Villi or Granulations
Pia Mater
Delicate membrane that hugs the surface of CNS and consists of a single cell layer + astrocyte processes
How are water-soluble molecules and ions blocked from crossing the BBB into the CNS?
Ridonkadonk numerous tight junctions on the endothelial cells lining the blood vessels.
What can directly diffuse across the BBB?
Lipid-soluble molecules and gases
How do ions cross the BBB?
Regulated membrane channels! and/or Facilitated transport (down a gradient) and energy-dependent receptor-mediated transport (up a gradient).
Structure of a Tight Junction in the BBB
A group of cell adhesion molecules (Claudin, Occludin, JAM) expressed on adjacent membranes.
These homologous molecules form homotypic interactions with each other.
They are held together by cytoskeletal structures (actin, binding proteins, etc)
They exist as sheets along the cell to prevent the passage of any specific molecule between the vessel lumen and CNS
Which transporters are on the lumen side of the BBB?
Glut1 (Glucose) L-System (Leucine) Na+ MCT1 L-System (L-DOPA)
Which transporters are on the CNS side of the BBB?
Glut1 (Glucose) LAT1 (L-System) ATA2 (A-System) Na/K ATPase MCT1 L-System (L-DOPA)
Which transporters are on both sides of the BBB?
Glucose Transporters
L-System
Acidic Transporters
Which transporters are exclusive to the CNS side of the BBB
LAT1
ATA2
Na/K Pump
How is Parkinson’s treated with L-DOPA?
L-DOPA enters endothelial cell, is converted intracellularly to Dopamine, enters CNS through transporter
Flow of CSF - Between LV & 3V
Foramina of Monro
CSF is produced where?
Choroid Plexus in the Lateral Ventricle, 3rd Ventricle & 4th Ventricle.
Flow of CSF - Between 3V and 4V
Cerebral Aqueduct (Aqueduct of Sylvius)
Flow of CSF - Between 4V and Subarachnoid Space
Foramina in 4V Cisterns: Superior Cistern Cisterna Magna Interpeduncular Cistern Pontine Cistern Lumbar Cistern (in caudal spinal cord)
Flow of CSF - Between Subarachnoid Space and Sagittal Sinus
Arachnoid Granulations
What happens when you develop a space-occupying lesion near the Foramina of Monro or the Cerebral Aqueduct?
These narrow passageways get compressed and leads to a build-up of CSF in the isolated chambers.
Hydrocephalus
Treat with a surgical shunt and/or eliminate the lesion
Arteries supplying the Spinal Cord
Anterior Spinal Artery
Posterior Spinal Artery
Radicular Arteries
What gives rise to the Anterior Spinal Artery?
Vertebral Arteries
What gives rise to the Posterior Spinal Artery?
Vertebral Arteries
What gives rise to the Radicular Arteries?
Segmental arteries off the Aorta
Which part of the spinal cord is the least vascularized (and thus the most vulnerable to ischemia)?
Thoracic
Where does the Cervical Spinal Cord get its blood supply?
Anterior Spinal Artery
Posterior Spinal Artery
List the Major Branches of Posterior and Anterior Circulation from caudal to rostral
Vertebral Artery Posterior Inferior Cerebellar Artery Anterior Spinal Artery Anterior Inferior Cerebellar Artery Basilar Artery Superior Cerebellar Artery Posterior Cerebral Artery Posterior Communicating Artery Middle Cerebral Artery Interior Carotid Artery Anterior Cerebral Artery Anterior Communicating Artery
Components of the Circle of Willis
PCA PComm IC/MCA ACA AComm
What part of the Circle of Willis do people sometimes not have?
PComm (unilateral or RARELY bilateral)
Posterior Circulation - Blood Supply of the Brainstem
Paired Vertebral Arteries PICA ASA PSA Basilar AICA SuCe PCA
Middle Cerebral Artery Path/Territory
Branches off Internal Carotid
Meanders around Insular Cortex
Emerges and supplies dorsolateral aspects of Frontal & Parietal Lobes, as well as part of the Occiptial Lobe, and the superior aspect of the Temporal Lobe
Anterior Cerebral Artery Path/Territory
Medial surface of Frontal and Parietal Lobes
Posterior Cerebral Artery Path/Territory
Inferior surface of Temporal Lobe, Parietal Lobe and Occipital Lobe
Lateral and medial surface of Occipital Lobe
Where do the ACA and MCA anastomose?
Superior surface of Frontal and Parietal Lobes
Where do the ACA and PCA anastomose?
Medial surface of Occipital Lobe
Where do the MCA and PCA anastomose?
Lateral and inferior surface of Occipital and Temporal Lobes
Penetrating branches of the MCA
Lenticulostriate Arteries
Penetrating branches of the ACA
Medial Striate Arteries
What is supplied by the Anterior Choroidal Artery?
Posterior parts of the internal capsule
