L2 - HARC: Vasculature of the CNS Flashcards
Describe and differentiate between the cerebral, cerebellar and brainstem arterial supply and trace their origin and anastomosis. Describe cerebrospinal fluid circulation and abnormalities that may interrupt the flow of CSF. Define and describe the dural venous sinuses and their venous flow pattern. Describe how a haemorrhage or blockage could disrupt the flow of arterial, venous or CSF flow and the resulting implications.
What are the 3 main arteries supplying the head and neck?
Common Carotid
- External CC
- Internal CC
Subclavian
- Vertebral
Where does bifurcation of CC artery occur?
C4
What are the meninges of the brain?
3 layers of protective tissue covering brain:
- dura mater
- arachnoid mater
- pia mater
What does the ECa commonly supply?
Predominantly extra-cranial structures
Exception: supplies meninges intracranially via the middle meningeal artery
What 2 systems are joined together by the Cerebral arterial circle (of Willis)?
- Carotid (anterior) system
2. Vertebrobasilar (posterior)
What makes up the anterior carotid system?
Right Internal carotid artery
Left ICa
What makes up the posterior vertebrobasilar system?
Vertebral arteries joining to become basilar artery.
run in transverse foramina of first 6 vertebrate
Define anastomosis?
connection between two normally divergent structures
Where does the ICa enter skull?
Enters via carotid canal
Passes over the foramen lacerum
What is the foramen lacerum?
hole in base of skull. filled with connective tissue and meningeal branches from ascending pharyngeal artery and emmisary veins from cavernous sinus to pterygoid venous plexus.
What is the carotid siphon?
curve in cavernous segment. portion of artery is surrounded by filaments of the sympathetic trunk. Lateral side - abducent CN VI
What is the origin of the vertebrobasilar system?
First part of subclavian artery
How does the vertebrobasilar system enter the skull?
Foramen magnum.
forms the basilar artery on anterior surface of brain stem, lying on top of clivus of the cranial base
What arteries make up the cerebral arterial supply?
Anterior cerebral artery
Posterior (PCa)
Middle (MCa)
Describe passage of Anterior cerebral artery
forward, medially under corpus callosum.
then superiorly and posterioly along superior surface of corpus callosum?
What is the corpus callosum?
thick nerve tract consisting of a flat bundle of commissural fibers, beneath cerebral cortex in brain.
What areas does the anterior cerebral artery supply?
Frontal lobes.
Medial aspect of parietal lobes
Optic chiasm
Lower limb motor and sensory cortexes.
Describe passage of Posterior cerebral artery?
PCa terminal branch of basilar artery.
Passes posterioly otw supplying parietal lobe.
Supplies occiptal lobe - visual cortex
Describe the passage of the middle cerebral artery?
Passes laterally towards temporal lobe up to lateral aspects of cerebrum.
Initially travels through lateral fissure.
What areas and lobes does the middle cerebral artery supply?
Temporal, parietal and occipital lobes.
Broca’s area- speech
Wernicke’s - language comprehension
Head and neck areas of motor and sensory cortexes.