Vasculature Flashcards
Which vessel is responsible for an extradural haematoma?
middle meningeal arteries
Which vessel is responsible for a sub dural haematoma?
cerebral bridging veins
Which vessel is responsible for a sub-arachnoid haematoma?
Cerebral arteries
Which three longitudinal arterial vessels run the length of the spinal cord?
- singleanterior spinal artery
2. pairedposterior spinal arteries
Where does the anterior spinal artery arise?
- in a Y-shaped configuration from the two vertebral arteries at the level of the medulla oblongata
2, descends along the ventral surface of the cord in the midline
When do the posterior spinal arteries arise?
- from either the vertebral arteries
- or the posterior inferior cerebellar arteries
- run caudally on the posterolateral surface of the cord
How much do the anterior and posterior spinal arteries supple?
insufficient to supply the cord below cervical levels
Where do the anterior and posterior spinal arteries receive reinforcement from?
- anastomosis withradicular arteriesderived from segmental vessels, including:
1. the ascending cervical
2. intercostal
3. lumbar arteries
How do the radicular arteries travel?
- pass through the intervertebral foramina
- divide into anterior and posterior branches
- which run with the dorsal and ventral spinal nerve roots, respectively
Where does the great radicular artery arise from?
lateral intercostal or lumbar artery at any level between T8 and L3
Where is the blood supply of the spinal cord most vulnerable?
- thoracic region
- in the anterior portion of the cord
What does occlusion of the anterior spinal artery, usually secondary to. dissection of the descending thoracic aorta lead to?
- acute thoracic cord syndrome
2. with paraplegia and incontinence
Which tracts are affected in occlusion of the anterior spinal artery?
- spinothalamic modalities of pain and temperature are preferentially lost
- The proprioceptive functions of the dorsal columns are relatively preserved
What is the venous drainage of the spinal cord like?
follows a basically similar pattern to the arterial supply
How many venous channels exist?
six longitudinal
What are these venous cahnnels?
- anteriorandposterior spinal veins(run in the midline)
- bilaterally pairedanterolateralandposterolateral veinsare situated near the lines of attachment of the ventral and dorsal nerve roots, respectively.
How do these vessels drain?
viaanteriorandposterior radicular veinsinto theinternal vertebral venous plexus(epidural venous plexus)
Where is the internal vertebral venous plexus?
between the dura mater and the vertebral periosteum
What does the internal venous plexus communicate with?
- anexternal vertebral venous plexus
- thence with the ascending lumbar veins, the azygos and hemiazygos veins
What are the two main vessels that supply the brain?
- internal carotid arteries
- vertebral arteries
Where does the internal carotid artery arise from?
common carotid artery
How does the internal carotid artery enter the middle fossa of the cranial cavity?
through the carotid canal
What is the course of the internal carotid artery?
- follows a series of characteristic bends: thecarotid syphon
- passes forwards through the cavernous sinus
- then upwards on the medial aspect of the anterior clinoid process
- reaching the surface of the brain lateral to the optic chiasm
What does the internal carotid. artery do along its course?
gives rise to a number of pre-terminal branches
Where do hypophyseal arteries arise from?
intra-cavernous section of the internal carotid to supply the neurohypophysis
What do the hypophyseal arteries form?
pituitary portal system of vessels by which releasing factors are carried from the hypothalamus to the adenohypophysis
What is the path of the ophthalmic artery?
into the orbit through the optic foramen
What does the opthalamic artery supply?
- structures of the orbit
- the frontal and ethmoidal sinuses
- the frontal part of the scalp 4. dorsum of the nose
What does the anterior choroidal artery supply?
- optic tract
- the choroid plexus of the lateral ventricle
- the hippocampus
- some of the deep structures of the hemisphere
- including the internal capsule and globus pallidus
What is the journey of the posterior communicating artery?
passes backwards to join the posterior cerebral artery, thus forming part of the circle of Willis
What does the internal carotid artery divide into lateral to the optic chiasm?
- two terminal branches:
- anteriorandmiddle cerebral arteries
What is the journey of the anterior cerebral artery?
- courses medially
- above the optic nerve
- then passes into the great longitudinal fissure - between the frontal lobes of the cerebral hemispheres
What is the anterior cerebral artery joined by?
corresponding vessel of the opposite side by the shortanterior communicating artery
What does the anterior cerebral artery do in the longitudinal fissure?
- follows the dorsal curvature of the corpus callosum
- branches ramifying over the medial surface of the frontal and parietal lobes
- which it supplies
- Fine terminal branches also extend out of the great longitudinal fissure to supply a narrow lateral band of frontal and parietal cortices
What territory does the anterior cerebral artery supply?
motor and sensory cortices for the lower limb
What is the largest of the three cerebral arteries?
middle cerebral artery
What is the journey of the middle cerebral artery?
passes laterally from its origin to enter the lateral fissure within which it subdivides, its branches supplying virtually the whole of the lateral surface of the frontal, parietal and temporal lobes
What is the territory supplied by the middle cerebral artery?
- primary motor and sensory cortices for the whole of the body, excluding the lower limb
- It also serves the auditory cortex and the insula within the depths of the lateral fissure
- Since the structures supplied by branches of the internal carotid artery are normally perfused almost entirely from this source, they are often referred to as being supplied by the ‘internal carotid system’
Where does the vertebral artery arise from?
- subclavian artery
- ascends through the foramina transversaria of the cervical vertebrae
- enters the cranial cavity through the foramen magnum, alongside the ventrolateral aspect of the medulla
What branches do the vertebral arteries give rise to?
number of branches, including the anterior and posterior spinal arteries, which supply the medulla and spinal cord
What is the largest branch of the vertebral artery?
- posterior inferior cerebellar artery
2. supplies the inferior aspect of the cerebellum
How is the midline basilar artery formed?
- as they pass rostrally, the two vertebral arteries converge
- uniting at the junction of the medulla and pons to form the midlinebasilar artery
What is the course of the basilar artery?
- Lengths of pons
- Supplies with small pontine branches
What else does the basilar artery give rise to and supply?
- Anterior inferior cerebellar artery: supplies anterior and inferior portion of the cerebellum
- Labyrinthe artery: supplies inner ear
What does the basilar artery do at the junction of the pons and midbrain?
divides into superior cerebellar arteries and posterior cerebral arteries
What do the superior cerebellar arteries supply?
superior aspect of the cerebellum
What do the posterior cerebral arteries supply?
- curves around the midbrain to supply the
1. visual cortex of the occipital lobe
2. the inferomedial aspect of the temporal lobe
What is supplied by the ‘vertebrobasillar system’?
brain regions (brainstem, cerebellum and occipital lobe) served by the vertebral and basilar arteries and their branches
What are the internal carotd and vertebrobascillar systems joined by?
- two thin vessels, theposterior communicating arteries ( pass rostrocaudally between the ends of the internal carotid arteries )
- posterior cerebral arteries
What does the circle of willis encircle?
- optic chiasm
2. floor of the hypothalamus and midbrain
Why is the anastomotic arrangement of vessels important?
- obstruction or narrowing of the proximal parts of the cerebral arteries, might be compensated for by circulation of blood through the communicating arteries
- Depends on size of communicating arteries
What are perforating arteries?
numerous small vessels penetrate the surface of the brain, two main groups
- Anterior perforating arteries
- Posterior perforating arteries
What are anterior perforating arteries arise?
- anterior cerebral artery
- anterior communicating artery
- the region of origin of the middle cerebral artery
What is the journey of the anterior perforating arteries?
enter the brain in the region between the optic chiasm and the termination of the olfactory tract (anterior perforated substance )
What do the anterior perforating arteries supply?
supply large parts of:
- the basal ganglia
- the optic chiasm
- the internal capsule
- the hypothalamus
Where do the posterior perforating arteries arise?
- posterior cerebral
- posterior communicating arteries
What is the journey of the perforating arteries?
Enter the brain in the region between the two crura cerebri of the midbrain (posterior perforated substance)
What do the perforating arteries supply?
- ventral portion of the midbrain
2. parts of the subthalamus and hypothalamus
What is an infarction?
sudden occlusion of a cerebral artery leads to death of brain tissue
What is a cerebral haemmorhage?
rupture of a blood vessel causes bleeding into the brain
What are strokes related to the carotid artery and its cerebral branches associated with?
- focal epilepsy
- a contralateral sensory/motor deficit
- a psychological deficit (e.g. aphasia)
What are Strokes involving the vertebrobasilar circulation lead to?
focal brainstem syndrome
What is an aneurysm?
abnormal, balloon-like swelling of an artery
When is an aneurysm a surgical emergency?
aneurysm ruptures and blood projects around the brain in the subarachnoid space (subarachnoid haemorrhage) and into the brain (intracerebral haemorrhage)
What is an angioma or arteriovenous malformation?
- congenital collection of swollen blood vessels that can rupture
- causing cerebral haemorrhage
- or that can ‘steal’ blood from adjacent brain regions, leading to epilepsy and a focal cerebral syndrome
What are the three sorts of vessels that contribute to the venous drainage of the brain?
- Deep veins
- Superficial veins
- Dural venous sinuses
- None of these vessels contains valves
Which veins drain the internal structures of the forebrain?
Deep cerebral veins
What do the thalamostriate veinand thechoroidal vein drain?
- basal ganglia
- thalamus
- internal capsule
- choroid plexus
- hippocampus.
What does these vessel merge to form within each cerebral hemisphere?
internal cerebral vein
What do the two internal cerebral veins merge to form? Where?
-great cerebral vein(of Galen) -lies beneath the splenium of the corpus callosum
What is the great cerebral vein continuous with?
- continuous posteriorly with the straight sinus (see below) 2. lies in the midline of the tentorium cerebelli, along its course of attachment to the posterior part of the falx cerebri
Where do superficial veins lie?
within the subarachnoid space
What do superior cerebral veins primarily drain? And empty into?
- drain the lateral surface of the cerebral hemispheres
- empty into the superior sagittal sinus
What is the journey of the superficial middle cerebral vein?
- runs along the line of the lateral fissure
- empties into the cavernous sinus
Where do the deep and superficial cerebral veins drain into?
dural venous sinuses
What are the two major anastomotic channels?
- superior (great) anastomotic vein: drain into superior sagittal sinus
- inferior anastomotic vei, which drain into transverse sinus
What are the dural venous sinuses?
channels formed between the two layers of dura mater
Where is the superior sagittal sinus?
along the line where the falx cerebri attaches to the interior of the cranium
Where does the superior sagittal sinus receive blood from?
- primarily from the superior cerebral veins
- which ramify over the lateral surface of the cerebral hemispheres
Where is the inferior sagittal sinus?
free border of the falx encloses the smallerinferior sagittal sinusinto which flow veins on the medial aspect of the hemisphere
Where does the large straight sinus lie? What runs into it?
- Within the tentorium cerebelli, along the line of its attachment to the falx
- into this runs the great cerebral vein, which drains the deep structures of the forebrain, and the inferior sagittal sinus
Where does the superior sagittal sinus and the straight sinus converge?
at theconfluence of the sinuses - lies adjacent to the internal occipital protuberance
What happens to the blood at the confluence of sinuses?
blood flows laterally on either side in thetransverse sinus
Where does the transverse sinus lie?
- . lies along the line of attachment of the tentorium to the occipital bone
- continuous with thesigmoid sinus
What does the sigmoid sinus join?
joins theinternal jugular veinat the level of the jugular foramen
Where does the cavernous sinus lie?
lateral to the body of the sphenoid bone
Where does the cavernous sinus receive blood from and drain?
- from the middle cerebral vein
- drains into the internal jugular vein (via the inferior petrosal sinus) and into the transverse sinus (via the superior petrosal sinus)
What are the two cavernous sinuses connected by?
- intercavernous sinuses - lies anterior and posterior to the hypophysis
- forming a venous circle around it (the circular sinus)
How are the dural venous sinuses connected?
to extracranial veins viaemissary veins, which pass through the bones of the skull
Is thrombosis of the sagittal sinus common?
a rare complication of childbirth, blood clotting disorders and ear infection
What does obstruction of the venous drainage of the brain lead to?
cerebral swelling (oedema) and the syndrome ofraised intracranial pressure
How does cerebral damage caused by venous infarction manifest?
as epileptic seizures and focal paralysis of the limbs
What happens in cavernous sinus thrombosis?
- acute pain
- swelling of the orbit and contents
- ophthalmoplegia
- ptosis
- numbness of the face
