Blood supply to the nervous system Flashcards
What arteries are responsible for blood supply to the brain?
Vertebral arteries
ICA
- Anterior Cerebral A
- Anterior communicating A
- Ophthalmic A
- Internal carotid A
- Middle Cerebral A
- Posterior Communicating A
- Posterior cerebral A
- Pontine A
- Basilar A
- Labyrinthine A
- Anterior inferior cerebellar A
- Posterior inferior cerebellar A
- Vertebral A
- Anterior Spinal A
From which arteries do the left & right vertebral arteries arise?
Subclavian arteries
At what vertebral level do the left & right internal carotid arteries arise?
C4
How is the basilar artery formed and which part of the brainstem is it most closely related to?
Formed from the two vertebral arteries at the junction between the Medulla & the Pons. – It ascends up the basilar sulcus on the anterior side of the Pons.
Which arteries complete the posterior of the Circle of Willis by linking the internal carotid arteries to the posterior cerebral arteries?
PCA
Which artery completes the anterior of the Circle of Willis by linking the anterior cerebral arteries?
ACA
Identify the three cerebral arteries. In which fissure/groove /sulcus of the brain do they travel?
- Anterior cerebral artery Median- Longditudinal fissure
- Middle cerebral artery-Lateral sulcus
- Posterior cerebral artery- Lateral fissure
Which cerebral artery/arteries supplies each of the following functional areas of the cerebral hemispheres - be as specific as you can:
Primary motor cortex MCA & ACA
Primary sensory area MCA & ACA
Primary visual cortex PCA
Primary auditory area MCA
Area for olfaction MCA
What parts of the brain do the vertebro basilar system sypply?
Cervical Spinal cord, The Medulla, Pons, Midbrain, & the posterior part of the circle of Willis. (cerebellum, thalamus & occipital lobes)
Which cerebral artery runs immediately superior to the superior cerebellar arteries?
Posterior cerebellar artery
Which cranial nerve emerges from just above the superior cerebellar artery?
CN III
What are the clinical manifestations of palsy of CNIII
Only the Lateral Rectus & Superior Oblique muscles are still innervated so the eye points downwards & outwards. Also get a fixed dilated pupil.
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 rate and blood pressure.
What is the sympathetic motor nerves?
From the superior cervical 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
What is the brain drained by?
A series of veins which drain into dural venous sinuses. These sinuses are present between the periosteum and the cranial dura
What are cerebral veins 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 these dural venous sinuses drain into?
IJV
Through which foramen in the skull does the vein you have named above pass?
Jugular foramen
What is the problem with the connection between intracranial venous sinuses and extracranial venous network?
Major routes of drainage of blood from the brain but they can be potential routes of infection which may be carried in the blood
What is the superior opthalmic vein drain?
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.
What are emissary veins?
Emissary veins are small veins that connect the cranial venous sinuses with the diploe of the skull containing the blood sinuses in the bone marrow of the diploe which in turn are continuous with the veins in the superficial fascia overlying the outer part of the skull and scalp.
What are inferior petrosal sinuses?
Sinuses that 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
What is the cavernous sinus?
Venous sinus that has a number of neurovascular structures that pass through it
What veins drain into the cavernius sinus?
Superior & Inferior Ophthalmic Veins, Superficial middle cerebral vein & sphenoparietal sinus & the emissary veins
What structures are closely related to the cavernous sinus?
Optic tract, Optic Chiasma, ICA
What is cavernous sinus thrombosis?
Clinical condition due to a spreading of infection from the nose, sinuses, ears or teeth. Reflect on how infections may spread to it from these regions
What are emissary veins?
Emissary veins have no valves – so blood can flow in any direction depending on the prevailing pressure gradient; since the cavernous sinuses receive blood via this root, it allows for easy spread of infections from the face (area between the bridge of the nose & the nasolabial folds)
CST results in bulging eyes and loss of vision, why?
This compresses the Nerves that pass through the cavernous sinus.
Branches from which arteries fuse to form the anterior spinal artery?
Branches from the vertebral arteries. – anterior vertebral
Which arteries are the posterior spinal arteries branches of
In 75% of people posterior inferior cerebellar artery – in 25% of people from the vertebral arteries.
What do the anterior and posterior spinal vein join with?
The internal vertebral venous plexus lying in the epidural space
What does the internal vertebral venous plexus do?
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.
