Flashcards in Week 1 - Dry Room Deck (61):
From which arteries do the left and right vertebral arteries arise?
From which arteries do the left and right internal carotid arteries arise?
Common carotid artery
How is the basilar artery formed and which part of the brainstem is it most closely related to?
Two vertebral arteries converge, uniting at the junction of the medulla and pons
Most closely related to medulla
Which artery completes the anterior of the Circle of Willis by linking the anterior cerebral arteries?
Anterior communicating artery
Which arteries complete the posterior of the circle of willis by linking the internal carotid arteries to the posterior cerebral arteries?
Posterior communicating artery
In which fissure/ groove / sulcus of the brain does the anterior cerebral artery travel?
Median longitudinal fissure
In which fissure/ groove / sulcus of the brain does the middle cerebral artery travel?
Which cerebral artery/arteries supply the primary motor cortex?
Anterior and middle cerebral artery
Which cerebral artery/arteries supply the primary sensory area?
Anterior and middle cerebral artery
Which cerebral artery/arteries supply the primary visual cortex?
Posterior cerebral artery
Which cerebral artery/arteries supply the primary auditory area?
Middle cerebral artery
Which cerebral artery/arteries supply the area for olfaction?
Posterior cerebral artery
What parts of the brain do the vertebra-basilar system supply?
Which cerebral artery runs immediately superior to the superior cerebellar artery?
Posterior cerebral artery
Which cranial nerve emerges from just above the superior cerebellar artery?
Aneurysms of the posterior cerebral artery are common in a location where it causes palsy of the cranial nerve III emerging just below.
What are the clinical manifestation of palsy of this cranial nerve?
Unable to move affected eye properly
Eye adopts a resting "down and out" position
Why is there nerve supply to the arteries supplying the brain?
Due to the importance of the brain, there is a good combination of sensory and motor nerves which help to control blood flow to the brain.
What is the carotid sinus?
This is a dilatation located on the terminal part of the common carotid artery (or the proximal part of the internal carotid artery).
It is a pressure receptor which monitors the flow of blood to the head, including the brain.
Sensory nerves from the carotid sinus run in the glossopharyngeal nerve and the vagus nerve.
What is the carotid body?
This is an area on the posterior wall of the terminal part of the common carotid artery in the neck.
It contains chemoreceptors which are sensitive to low oxygen levels (anoxia).
Sensory nerves from these receptors run in the glossopharyngeal nerve.
Detection of anoxia will stimulate increased heart rate, respiration and blood pressure
What is the sympathetic motor supply to the brain?
Sympathetic motor nerves from the superior cervicle ganglion form a plexus around the internal carotid artery.
This plexus enters the skull, with the artery, through the carotid canal, and continues along the main branches of the internal carotid artery
Explain the venous drainage of the brain
The brain is drained by a series of veins which drain into dural venous sinuses.
These sinuses are present between the periosteum and the cranial dura.
Cerebral veins are often divided into a superficial and deep group.
Among the deep group the Great cerebral vein (of Galen) can be seen on wet specimens and models
Into which vein in the neck do the dural venous sinuses drain into?
Internal jugular vein
Through which foramen in the skull does the internal jugular vein pass?
In addition to the internal jugular vein there are other connections between the intracranial venous sinuses and the extra cranial venous network.
Since these are not major routes for blood drainage why do we need to know about them?
These are potential routes of infection which may be carried in the blood (e.g. following cut/ abrasion to the scalp/ face
How do the veins in the brain and the cranial venous sinuses differ to veins outside the skull?
Do not have valves to prevent back flow of blood from outside the cranium back into the cranium
Name the important connection between intracranial venous sinuses and extra cranial veins involving the superior ophthalmic vein
The superior ophthalmic vein drains into the cavernous sinus within the cranial cavity.
On the outside of the cranial cavity it is continuous with the facial vein.
Name the important connection between intracranial venous sinuses and extra cranial veins involving the emissary veins
Emissary veins are small veins that connect the cranial venous sinuses with the dipole of the skull containing the blood sinuses in the bone marrow of the dipole which in turn are continuous with the veins in the superficial fascia overlying the outer part of the skull and scalp.
Name the important connection between intracranial venous sinuses and extra cranial veins involving the inferior petrosal sinuses
The inferior petrosal sinuses lie at the base of the brain and are connected to each other (left and right) by the basilar sinus.
This small sinus also communicates inferiorly with the internal vertebral sinus
Why do we need to know about the cavernous sinus?
This venous sinus deserves a special mention because of a number of neuromuscular structures which pass through it
What veins drain into the cavernous sinus?
Middle cerebral vein
Superior and inferior ophthalmic veins
What structures does the cavernous sinus closely relate to?
Nerves: Oculomotor (III), Trochlear (IV), Ophthalmic (V1), Maxillary (V2), Abducens (VI)
Internal carotid Artery
(ruptures = arteriovenous fistula (carotidcavernous fistula))
Pituitary gland (pituitary adenoma)
Connections with facial vein through superior ophthalmic vein (Infections from danger area of face)
Explain cavernous sinus thrombosis
CST is a clinical condition due to spreading of infection from the nose, sinuses, ears or teeth.
Caused by a clot in the cavernous sinus usually due to infection
CST results in bulging eyes and loss of vision among other things. This is due to the failure of the superior and inferior ophthalmic veins to drain and also paralysis of the nerves coursing through it.
Emergency which is treated with antibiotics or sometimes drainage.
What arteries supply the spinal cord?
3 longitudinally running spinal arteries (1 anterior and 2 posterior) and multiple segmental spinal arteries supply the spinal cord
Branches from which arteries fuse to form the anterior spinal artery?
Which arteries are the posterior spinal arteries branches of?
Describe the venous drainage of the spinal cord
In general, the distribution of the veins of the spinal cord is similar to that of the spinal arteries.
The longitudinally oriented anterior and posterior spinal veins communicate freely with each other and join the internal vertebral (epidural) venous plexus lying in the epidural space.
This plexus of veins passes superiorly within the vertebral canal through the foramen magnum to communicate with the dural sinuses and veins within the skull.
The internal vertebral venous plexus also communicates with the external vertebral venous plexus on the external surface of the vertebrae.
What fluid circulates in the subarachnoid space?
Apart from CSF what other structures are present in the subarachnoid space?
Numerous arteries and veins
Which structures does the fall cerebri separate?
To what bony structures does the fall cerebra attach anteriorly?
Ethmoid and crista gali processes
Which dural venous sinus runs within the upper border of the falx cerebri?
Inferior sagittal sinus
Which dural venous sinus runs along the upper border of the falx cerebri?
Superior sagittal sinus
Which structures does the tentorium cerebelli separate?
Cerebellum from cerebrum
To what bony points does the anterior edge of the tentorium cerebelli attach to?
Superior angle of the petrous part of the temporal bone
Which dural venous sinus runs along the attachment of the falx cerebri to the tentorium?
Superior Petrosal Sinus
What is the dural fold that separates the two cerebellar hemispheres called?
What is the fold of dura that surrounds the pituitary stalk called?
What is the arterial supply of the dura mater?
Branches of numerous arteries including the Internal Carotid artery, branches of the External Carotid Artery and vertebral arteries
One of the clinically important meningeal arteries is the middle meningeal artery.
This is a specific branch of the maxillary artery that supplies the dura mater
Through which foramen in the skull does the middle meningeal artery enter the cranial cavity?
What are the ventricles of the brain?
Ventricles are interconnected spaces/ cavities that lie within the brain.
The central canal of the spinal cord is a continuation of the ventricular system within that structure
What embryological structures are the ventricles formed from?
Cavity of the neural tube
What is the name given to the specialised structures lining the ventricles that generate CSF?
Where do the parts of the lateral ventricle lie?
Anterior horn = frontal lobe
Body = Parietal lobe
Posterior horn = Occipital lobe
Inferior horn = Temporal lobe
Where does the inter ventricular foramen (foramen of Monro) lie?
Between column of fornix and anterior pole of the thalamus
(Just under corpus calosum)
Where does the third ventricle lie?
Bordered In between the thalamus and hypothalamus
Where does the cerebral aqueduct (of the midbrain) lie?
Runs the length of the midbrain beneath inferior and superior colliculi
Where does the 4th ventricle lie?
Dorsal surface of brainstem beneath cerebellum
How does CSF pass into the subarachnoid space from the 4th ventricle?
Foramen of Magendie
At which location is cerebrospinal fluid finally resorbed back into the general circulation
Arachnoid granulations of the dural venous sinuses
Explain the clinical significance of CSF
If the circulation of CSF is restricted then there will be an increase in intracerebral pressure.
In infancy congenital defects in circulation lead to a progressive enlargement of the head and a reciprocal reduction in the cerebral matter.
This condition is known as hydrocephalus and can occur in isolation or as part of spina bifida.
This is a very treatable condition using a shunt to redirect the fluid out of the cerebral circulation into the deep venous system.