Blood supply to the nervous system

Question 1

What arteries are responsible for blood supply to the brain?

Answer 1

Vertebral arteries

ICA

Question 2

Answer 2

1. Anterior Cerebral A
2. Anterior communicating A
3. Ophthalmic A
4. Internal carotid A
5. Middle Cerebral A
6. Posterior Communicating A
7. Posterior cerebral A
8. Pontine A
9. Basilar A
10. Labyrinthine A
11. Anterior inferior cerebellar A
12. Posterior inferior cerebellar A
13. Vertebral A
14. Anterior Spinal A

Question 3

From which arteries do the left & right vertebral arteries arise?

Answer 3

Subclavian arteries

Question 4

At what vertebral level do the left & right internal carotid arteries arise?

Answer 4

C4

Question 5

How is the basilar artery formed and which part of the brainstem is it most closely related to?

Answer 5

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.

Question 6

Which arteries complete the posterior of the Circle of Willis by linking the internal carotid arteries to the posterior cerebral arteries?

Answer 6

PCA

Question 7

Which artery completes the anterior of the Circle of Willis by linking the anterior cerebral arteries?

Answer 7

ACA

Question 8

Identify the three cerebral arteries. In which fissure/groove /sulcus of the brain do they travel?

Answer 8

1. Anterior cerebral artery Median- Longditudinal fissure
2. Middle cerebral artery-Lateral sulcus
3. Posterior cerebral artery- Lateral fissure

Question 9

Which cerebral artery/arteries supplies each of the following functional areas of the cerebral hemispheres - be as specific as you can:

Answer 9

Primary motor cortex MCA & ACA

Primary sensory area MCA & ACA

Primary visual cortex PCA

Primary auditory area MCA

Area for olfaction MCA

Question 10

What parts of the brain do the vertebro basilar system sypply?

Answer 10

Cervical Spinal cord, The Medulla, Pons, Midbrain, & the posterior part of the circle of Willis. (cerebellum, thalamus & occipital lobes)

Question 11

Which cerebral artery runs immediately superior to the superior cerebellar arteries?

Answer 11

Posterior cerebellar artery

Question 12

Which cranial nerve emerges from just above the superior cerebellar artery?

Answer 12

CN III

Question 13

What are the clinical manifestations of palsy of CNIII

Answer 13

Only the Lateral Rectus & Superior Oblique muscles are still innervated so the eye points downwards & outwards. Also get a fixed dilated pupil.

Question 14

What is the carotid sinus?

Answer 14

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.

Question 15

What is the carotid body?

Answer 15

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.

Question 16

What is the sympathetic motor nerves?

Answer 16

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

Question 17

What is the brain drained by?

Answer 17

A series of veins which drain into dural venous sinuses. These sinuses are present between the periosteum and the cranial dura

Question 18

What are cerebral veins divided into?

Answer 18

A superficial and deep group. Among the deep group the Great cerebral vein (of Galen) can be seen on wet specimens and models.

Question 19

Answer 19

Question 20

Into which vein in the neck do these dural venous sinuses drain into?

Answer 20

IJV

Question 21

Through which foramen in the skull does the vein you have named above pass?

Answer 21

Jugular foramen

Question 22

What is the problem with the connection between intracranial venous sinuses and extracranial venous network?

Answer 22

Major routes of drainage of blood from the brain but they can be potential routes of infection which may be carried in the blood

Question 23

What is the superior opthalmic vein drain?

Answer 23

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.

Question 24

What are emissary veins?

Answer 24

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.

Question 25

What are inferior petrosal sinuses?

Answer 25

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

Question 26

Answer 26

Question 27

What is the cavernous sinus?

Answer 27

Venous sinus that has a number of neurovascular structures that pass through it

Question 28

What veins drain into the cavernius sinus?

Answer 28

Superior & Inferior Ophthalmic Veins, Superficial middle cerebral vein & sphenoparietal sinus & the emissary veins

Question 29

What structures are closely related to the cavernous sinus?

Answer 29

Optic tract, Optic Chiasma, ICA

Question 30

Answer 30

Question 31

What is cavernous sinus thrombosis?

Answer 31

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

Question 32

What are emissary veins?

Answer 32

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)

Question 33

CST results in bulging eyes and loss of vision, why?

Answer 33

This compresses the Nerves that pass through the cavernous sinus.

Question 34

Branches from which arteries fuse to form the anterior spinal artery?

Answer 34

Branches from the vertebral arteries. – anterior vertebral

Question 35

Which arteries are the posterior spinal arteries branches of

Answer 35

In 75% of people posterior inferior cerebellar artery – in 25% of people from the vertebral arteries.

Question 36

What do the anterior and posterior spinal vein join with?

Answer 36

The internal vertebral venous plexus lying in the epidural space

Question 37

What does the internal vertebral venous plexus do?

Answer 37

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.