Blood Supply, Meninges and CSF

Question 1

Describe the arterial supply to the brain in the common domestic species

Answer 1

1. Arterial supply is derived in all domestic species from cerebral arterial circle
2. Located on ventral aspect of brain, surrounding hypothalamus
3. gives off 5 main artery pairs to supply parenchyma

Question 2

What is the cerebral arterial circle?

What are the names of arteries coming off the cerebral arterial circle?

Answer 2

Circle of arteries that gives off arteries to supply diff bits of the brain

1. Cerebral arteries: 3 pairs
2. Cerebellar arteries: 2 pairs

Question 3

What are the names of the cerebral arteries and cerebellar arteries

Answer 3

Cerebral:
1. Rostral  
2. Middle
3. Caudal
Cerebellar: arteries that supply cerebellum
1. Rostral
2. Caudal

Question 4

What is the name for the artery that leaves the cerebral arterial circle caudally?

Answer 4

1. The ventral spinal artery = artery that supplies the spine

Question 5

Where does the supply to the cerebral arterial circle come from?
And why does the source matter

Answer 5

1. Internal carotid artery
2. Basilar artery (end of ventral spinal artery (bit closest to circle
3. Maxillary artery
4. Vertebral artery = branch off subclavian
5. source matters in terms of slaughter techniques

Question 6

How is blood supplied to the cerebral arterial circle?

Answer 6

1. Either directly

2. Via rete mirabile

Question 7

What are rete mirabile adn what is its purpose?

Answer 7

1. network of blood vessels = arterial supply into, lot of little arteries forming network, another artery coming out.
2. very rare
3. Purpose thought to cool blood down
4. purpose = slow speed

Question 8

Where does blood come from to brain in

a) dog and horse
b) sheep and cat
c) Ox

Answer 8

a) blood from internal carotid and basilar arteries
b) blood mainly frm maxillary artery via rete mirabile
c) blood from maxillary artery and vertebral artery via 2 rete mirabile

Question 9

What is the spinal cord blood supply?

Answer 9

1. Ventral spinal artery runs inside vertebral column

2. receives input from aorta (caudally) or vertebral artery (cranial)

Question 10

Why can strokes be so catastrophic?

Answer 10

1. not many interarterial communication - few inter arterial anastomoses = joining between arteries = = alternative route for blood incase one gets blocked
2. not much collateral circulation (more than one artery to same place)
3. means blockage of artery in CNS = buggered

Question 11

What does meninges mean?

Answer 11

MEMBRANES

Question 12

How many layers of the meninges are there adn what are they for?

Answer 12

1. 3

2. Physical protection, facilitate flow of CSF, provide framework for blood vessels to supply CNS tissue

Question 13

What is the outside layer of meninges called?

Structure

Answer 13

1. Dura mater. Thickest of the 3 layers
2. forms 2 layers within the skull which you cant separate: inner = meningeal, outer = endosteal
3. However in longitudinal fissure, inner meningeal folds down into fissue: Falx cerebri. Outer layer on top
4. At transverse fissure = same thing = tentorium cerebelli!
5. Between the layers of the dura, in between the cerebral hemispheres and cerebrum and cerebellum, = blood filled space (venus sinus) = form major drainage pathway

Question 14

What is special about the dura mater vs pia and Arachnoid

Answer 14

1. the only meningie that has a pain supply

2. Cranial nerve 5!

Question 15

Arachnoid mater

Answer 15

1. under Dura
2. Avascular
3. thin membrane, right up against dura
4. potential space between dura and A
5. subarachnoid space beneath arachnoid membrane which is criss crossed by connective tissue
6. sub = True space, has blood vessels and contains CSF
7. so membrane itself doesn’t have blood supply, space beneath does.

Question 16

Pia mater

Answer 16

1. highly vascular
2. very delicate, incredible thin
3. right up against brain, can’t pick up = confluent with tissue
4. Follows blood vessels into tissue and merges with tunica adventitia

Question 17

What is similar and different about the meningies in the spinal cord to the brain

Answer 17

1. same three meningies
2. Dura mater isn’t up against bone in spinal cord = epidural space filled with fat and connective tissue for protection, whereas in skull it lines it
3. In spinal pia mater gives off “supporting hammocks” that extend off sideways. Travels all the way through subarachnoid space into dura = suspends spinal chord in dura so spinal doesn’t flop down.

Question 18

Cuff zone

Answer 18

1. area where meningies stop and merge with linign of nerve (epineurum) (nerve) begins
2. area easier for drugs to access nerve

Question 19

Cerebrospinal fluid

Answer 19

1. bathes tissue outside brain (subarachnoid space)
2. and bathes tissue inside in ventricles
3. Fluid has free communication with interstitial fluid of the tissue
4. no cells, no protein, low amino acid content as a lot of neurotransmitters are amino acids, low and stable K+, relatively low glucose content Vs blood plasma
5. must be stable

Question 20

What is the CSF for?

Answer 20

1. Get rid of products of metabolism (constantly produced and drained)
2. brings in nutrients
3. Physical protection: cushioning
4. Volume buffer
5. circulates neurotransmitters

Question 21

Where is CSF found

Answer 21

1. sub arachnoid space
2. ventricles
3. Central canal in spinal chord

Question 22

Location and structure of ventricles

Answer 22

1. LATERAL VENTRICLES long horn shape in each cerebral hemisphere
2. 2 lateral ventricles communicate together to one circular 3rd ventricle that runs around Thalamus (deincephalon)
3. third V runs through channel called mesencephalic aquaduct = from third to fourth ventricle which sits under cerebellum
4. from here goes out through sides and into sub arachnoid space or down central canal of spinal chord

Question 23

Why is the thalamus so important

Answer 23

1. because all sensory information synapses in thalamus (expect from olfactory)