CNS Circulation Flashcards
Choroid Plexus
-produces CSF
-web of capillaries
-blood filtered 3x
Lateral Ventricles
-above thalamus
-2
-connected to 3rd ventricle by inter-ventricular foramina (Monro)
3rd Ventricle
-surrounded by diencephalon
-connected to 4th ventricle via cerebral aqueduct (sylvius)
4th Ventricle
-behind pons/medulla
-connects to central canal of SC
-drains into subarachnoid space via foramina of Luschka and midline foramen of Magendie
Falx Cerebri
-dense projections in inner layer of dura
-separates 2 hemispheres
Tentorium Cerebelli
-dense projections in inner layer of dura
-separate cerebellum from cerebrum
Epidural Hematoma
-bleeding above dura
-most often tearing of middle meningeal artery
-quick accumulation
-lens shaped
Sx:
-HA, nausea, disorientation
Subdural Hematoma
-bleeding below dura
-most often venous bleed
-not hemorrhage
-slower blood pool
-crescent shaped
Hydrocephalus
-abnormally high CSD in ventricles
Congenital:
-non-fused skulls, enlarged heads, downward gaze
Acquired:
-excessive pressure on white matter
-gait issues, incontinence, HA
Communicating:
-blocked at bottom of 4th ventricle
-occurs outside of system
Non-Communicating:
-blocked inside system (cerebral aqueduct)
Meningitis
-inflammation of meninges
-pain increases with upright position, head position, sneezing, neck stiffness, confusion
Homunculus Motor Cortex
-Precentral Gyrus
Medial: Genitals, toes, ankle, knee
Superomedial: trunk, hip, shoulder, elbow, wrist, hand
Superolateral: Hand (fingers pinky-thumb), face
Lateral: Face (top to bottom), jaw (talking), tongue (swallowing)
Homunculus Sensory Cortex
-Postcentral gyrus
Medial: Genitals, toes, ankle, knee
Superomedial: trunk, hip, shoulder, head, arm
Superolateral: Hand (fingers pinky-thumb), elbow, forearm, wrist
Lateral: Face (top to bottom), jaw, tongue, gums, pharynx
Vertebrobasilar A.
-posterior circulation of brain
Posterior Inferior Cerebellar A.
-bottom, posterior cerebellum
Anterior Inferior Cerebral A.
-front and bottom cerebrum
Superior Cerebellar A.
-top of cerebellum
-above CN III
Posterior Cerebral A.
-posterior cerebrum
-occipital lobe
-Posterior, medial, inferior temporal lobe
Internal Carotid A.
-anterior circulation of brain
Ophthalmic A.
eyes
Posterior Communicating A.
-connects PCA and ICA
-connects 1 side of ant to post
Anterior Cerebral A.
-medial cerebral hemisphere to parietal lobe
Anterior Communicating A.
-between ant. cerebral A.
Middle Cerebral A.
-lateral cerebral hemisphere
EXCECPT:
-superior and front parietal
-inferior temporal
Arteriovenous Malformation
-arteries fail to connect to capillaries
-congenital
-can be ill until rupture
Saccular Aneurysm
-most common (on cerebral A.)
-1 sided bulge
-Berry Aneurysm
Fusiform Aneurysm
-bilateral
-Sx occur near area
Pericytes
-cells surrounding BBB to control selectively permeable barrier
Blood Brain Barrier
-specialized barrier around capillaries
-controlled by tight junctions
-Absent in areas around hypothalamus and near 3rd and 4th ventricles
Cerebral Blood Flow
-More O2 needed for cortex than brainstem
-Cerebral arteries dilate if BP, O2 pH are low OR CO2 is high
Cerebral Edema
-swelling of the brain tissue
-High altitude cerebral edema, TBI, MI
-causes ischemia which causes dilation and more edema
Intracranial Pressure
-5-15mmHg
-normal pressure within skull monitored by lat ventricle
-can compress brain tissue, cause brain herniation
Cingulate Brain Herniation
-pressure against falx cerebri
-can cause issue with contra lower limbs
Uncal Brain Herniation
-pressure against midbrain
-can cause CNIII dysfunction and loss of consciousness
Central Brain Herniation
-pressure against diencephalon, moving brainstem down
-stretches basilar A.
-B paralysis and impaired consciousness
Tonsillar Brain Herniation
-pressure of cerebellar tonsils putting on brainstem
-impairs consciousness and 4th ventricle
Transient Ischemic Attack
-brief localized loss of brain function that resolves in 24h
-risk of another 20% in 3m
Cerebrovascular Accident
-stroke
-lasting longer than a day
-“brain attack”
Infarction
-80% of strokes
-mostly middle cerebral artery
-slow occlusion causes compensations
Embolus:
-blot from somewhere else
-sudden quick loss of function
Thrombus:
-narrowing or clot in area
-gradual worsening of function
Hemorrhage
-rupture of vessel
-20% of strokes
Causes:
-downstream loss of blood
-pressure
-irritant to brain tissue
Subarachnoid Hemorrhage
-sudden bad headache
Vertebral A. Stroke
-prone to shear forces from AA joint from abrupt cervical rotation
-gait issues, ataxia, HA
Basilar A. Stroke
-complete blockage causes death
-partial: tetraplegia, numbness, CN damage, locked in syndrome (only movements)
Anterior Cerebral A. Stroke
-hemiparesis loss to contra side
-personality changes
-lower limb issues
Middle Cerebral A. Stroke
-hemiparesis loss to contra side
-face and upper limb issues
L side: aphasia
R side: spacial relationships, neglect, nonverbal communication
Posteror Cerebral A. Stroke
-midbrain issues (thalamic syndrome), eye movement issues, cortical blindness (brain cant comprehend vision)
Pontine Arteries
-supplies pons
Torcula
-confluence of sinuses
-drains straight sinus and sup. saggital sinus
-drains to sigmoid
Cavernous SInus
-drains from blood supply of face and brain
-drains to sigmoid
Superior and inferior Petrosal Sinus
-drains from cavernous sinus
-drains to sigmoid
