Lab 4: Blood Supply/CSF Flashcards
Vertebral Arteries
Located on the ventral medulla; have spinal branches that include
Anterior spinal branches (anterior spinal artery)
Posterior spinal arteries
Anterior Spinal Branches Join to make Anterior Spinal Artery
Travels in the ventral median fissure
Posterior Spinal Arteries
Are difficult to find; descend near the attachments of the dorsal roots; often branch from the posterior inferior cerebellar Artery
Segmental Artery Branches
Vertebral, intercostal, lumbar and lateral sacral
Further subdivided into:
Anterior and posterior radicular arteries: that mainly supply the nerve roots, dorsal root ganglia and dura
Medullary arteries: branch from 8-10 of the segmental arteries and connect to the anterior and posterior spinal arteries to produce an arterial vasocorona that surrounds and supplies spinal cord
Artery of Adamkiewicz: a very large medullary artery, often branching from a lower intercostal or upper lumbar artery,m that makes a major contribution to the supply of the lower thoracic and upper lumbar spinal cord
Venous Return from the Spinal Cord
Blood from the spinal cord drains into 3 longitudinal systems: (Anastomose extensively) -spinal cord plexus -epidural (internal vertebral plexus) -external vertebral plexus
Vertebral-basilar system (posterior circulation)
Supplies:
Spinal cord, brainstem, cerebellum and parts of the medial forebrain
Internal Carotid System (anterior circulation)
Supplies most of the forebrain (telencephalon and diencephalon)
(Arterial Supply to the Brainstem) From the Vertebral Arteries
Anterior and posterior spinal arteries (posterior can originate from PICA)
Posterior inferior cerebellar arteries (PICA): long circumferential arteries
(Arterial Supply to the Brainstem) From the Basilar Artery
Paramedian pontine arteries (paramedian branches of basilar artery)
Short circumferential pontine arteries (short circumferential branches)
Anterior Inferior Cerebellar Arteries (AICA): long circumferential arteries
Superior cerebellar arteries (long circumferential arteries)
Posterior Cerebral Arteries (terminal branches)
Branches of the Internal Carotid Artery
Anterior cerebral artery
Middle cerebral artery
Great Arterial Circle of Willis
Variable, large vessel communication on the base of the brain, encircling the optic chiasm and mammillary bodies of the hypothalamus.
Communicating branches allow rerouting of blood between the anterior and posterior circulations (via posterior communicating arteries) and between left and right circulations (via an anterior communicating artery)
Frequently permits rerouting of blood around slowly-developing conclusions of the large vessels that supply the brain
Contributions of the Cerebral Arterial Circle (of Willis)
Posterior Cerebral Arteries Anterior Cerebral Arteries Middle Cerebral Arteries Posterior Communicating Arteries Anterior Communicating Artery
Middle Cerebral Artery Branches (in the lateral fissure)
Cortical branches that supply the lateral cortex
Anterior Cerebral Artery (longitudinal fissure)
Has cortical branches that supply the medial frontal and parietal cortex
Posterior Cerebral Artery
Winds around the midbrain; has cortical branches that supply the medial occipital and medial and inferior temporal cortex
Mid/Rostral Medulla Blood Supply
Paramedian: anterior spinal arteries
Anterolateral: Short circumferential branches of the vertebral artery
Posterolateral: posterior spinal arteries (caudally) as you move rostrally it becomes the long circumferential branches of PICA
Caudal Pons Blood Supply
Paramedian: Paramedian branches of the basilar artery
Anterolateral: short circumferential branches of the basilar artery
Posterolateral: long circumferential branches of the basilar Artery caudally and the anterior inferior cerebellar artery as you move rostrally
Rostral Midbrain Blood Supply
Paramedian: paramedian branches of the basilar artery bifurcation
Anterolateral: short circumferential branches of the posterior cerebral artery
Posterolateral: long circumferential branches of the posterior cerebral artery and some of the superior cerebellar artery
Venous Drainage of Spinal Cord and Brain
The veins that drain the brain run their course independent of the arteries. They anastomose freely and form four interconnected systems Intra-axial veins Superficial cerebral Veins Deep cerebral veins Dural Venous Sinuses
Intro-axial Veins
Collect capillary blood and travel in brain tissue; they drain into a serious of mostly superficial veins
Superficial Cerebral Veins
Drain the intra-axial veins of the cerebral cortex and underlying white matter
Traverse the SAS in cerebral sulci, superficial to cerebral arteries
Penetrate the arachnoid, the subdural space (as bridging veins) and the dura to drain into nearby dura venous sinuses
“Bridging” veins can tear in shear force injury and cause subdural hemorrhage
Deep Cerebral Veins
Drain deep structures
Dural Venous Sinuses
Are venous channels that are embedded in layers of cranial dura
Drain the superficial and deep cerebral veins
Eventually drain into the internal jugular vein
Lateral Ventricle Components
Anterior horn Body Atrium Posterior horn Inferior horn
Anterior Horn of Lateral Ventricle
In frontal lobe, anterior to the interventricular foramen
Body of the Lateral Ventricle
In caudal part of frontal lobe and in parietal lobe, at the level of the 3rd ventricle
Atrium of the Lateral Ventricle
Posterior expanded confluence of body, posterior and inferior horns
Posterior horn of Lateral Ventricle
In occipital lobe, posterior to the expansion of the atrium
Inferior Horn of Lateral Ventricle
In the temporal lobe, it passes anteriorly, inferiorly and laterally from the atrium; is located lateral to the other parts of the lateral ventricle
Right and Left Interventricular Foramen (Foramina of Monroe)
Open connections between the lateral and third ventricles; contains choroid plexus that is continuous with that of the lateral and 3rd ventricles
Midline parts of the ventricular system
Third Ventricle
Cerebral Aqueduct
Fourth Ventricle
Visibility of the Ventricular System in Sections
Frontal horn: anterior coronal and horizontal slices
Body: posterior coronal slice at level of the thalamus
Atrium: often visible in a horizontal slice
Temporal: in posterior coronal slice
Occipital horn: sometimes visible in a horizontal slice
Third ventricle: posterior coronal slice and in some horizontal slices
Choroid Plexus
In all parts of lateral ventricle except the frontal and occipital horns; extends from the lateral ventricle to the roof of the 3rd at the interventricular foramen
Third Ventricle (choroid plexus relation)
Has a roof with strips of choroid plexus hanging from vascular stalks
Median Aperture (foramen of Magendie)
A defect in the caudal end of the roof of the fourth ventricle (edges are often lost in preparation); allows CSF to exit the ventricular system and enter the SAS
Lateral Aperture (foramen of Luschka)
Find by pushing a probe into the lateral recess of the IV ventricle is another route for exit of ventricular CSF
Choroid Plexus in the roof of the fourth ventricle
Often lost in preparation
SAS
Has a complex contour that is also important in image analysis
Cortical Sulci
Contain “sulcal” CSF and cerebral arteries and veins within extensions of the SAS that surrounds entire CNS
Crests of Cortical Gyri
Are surrounded by a thin layer of Subarachnoid CSF that ids in protecting the soft cortical tissue
Cisterns
Expansions of SAS
Cerebellomedullary cistern (cisterna magna)
The large area between the dorsal surface of the caudal medulla and the ventral surface of the cerebellum
Pontine Cistern
area between the pons and the arachnoid and dura covering the base of the skull
Interpeduncular Cistern
Area between the anterior midbrain and the base of the skull
Quadrigeminal or superior cistern
Area posterior trio the midbrain and superior to the cerebellum
Ambient Cistern
Superior cistern is continuous laterally within a thin, curved layer of the SAS on each side that partially encircles the midbrain before opening into the interpeduncular cistern. The combo of these sheetlike extensions and the superior cistern is what’s referred to as the ambient cistern
Supratentorial Compartment
Above the level of the tentorium cerebelli and midbrain
Infratentorial compartment
Between the tentorium cerebelli and foramen magnum
Vertebral Canal
Continuous opening in the vertebral column for the spinal cord, meninges, and CSF
Areas of SASA in the supratentorial compartment
Peripheral SAS: CSF between the arachnoid mater and pia surface of the cortex
Sulcal SAS: CSF layer between adjacent gyri
Areas of the SAS in the infratentorial compartment
Superior Cistern Interpeduncular cistern Pontine cistern Cisterna magna Spinal SAS
Areas of the ventricular System
Lateral ventricle Interventricular foramen III Ventricle Cerebral Aqueduct IV Ventricle Position of the lateral aperture Position of the median aperture
Termination of the Spinal Cord
Usually at vertebral levels L1 or L2
Termination of the SAS and Dural Sac
usually at vertebral level S2
Lumbar Cistern
Caudal part of the SAS; is the most common site for removal of CSF in a lumbar tap
