Brain and SC anatomy

Question 1

What is the tentorium cerebelli osseum?

Answer 1

• Large projection at the junction of dorsal and cuadal walls forming the middle portion of the the tentorium cerebelli within the transverse fissure of the brain
• contains passages for branches of the dorsal intracranial venous sinus

Question 2

What is the denticulate ligament?

Answer 2

Subdural space of the SC if crossed by bilateral series of triangular ligaments that attache inner meninges to dural tube and indirectly suspend spinal cord in dura

Question 3

What makes CSF:

Answer 3

• Ependymal lining of the vet system
• Choroid plexus
• Pial vessels contribute

Question 4

What is the plexus of the lateral and third ventricles?

Answer 4

• Plexuses of each of the two lateral vents and of the third ven - that merge within the intervent foramen- develop within a fold of pia that becomes entrapped between the expanding tel vesicles and roof diencephalon

Question 5

What about the plexuses of fourth?

Answer 5

• Plexuses of fourth ventricle develop separately within the pia over the caudal medullary velum
• Plexuses invaginate into lumen of the fourth ventricle, part later reemerge into the arachnoid space by herniating through paired lateral openings in the roof

Question 6

What is the rate of CSF production and route?

Answer 6

• 30 ml/hr
• first circulates through vent system and moved on by filtration pressure and ciliary activity of the ependymal lining
• Escapes via lateral apertures of the fourth vent
• return to blood via arachnoid villi - pierce dura to enter dorsal sag venous sinus of brain
• some absorbed by perineural lymphatics

Question 7

What is the arterial circle supplied by?

Answer 7

• Paired internal carotid arteries
• Basiliar artery
• Internal carotid artery - connects with maxillary artery then joins circle

Question 8

What is the path of the internal carotid artery?

Answer 8

Arises as terminal branch of the common carotid at level of pharynx and then travels toward base of skull
In dog, must go through carotid canal in bone medial to tympanic bulla, then to cranial cavity via carotid foramen

Question 9

What arises from the rostral portion of the internal carotid artery?

Answer 9

• Rostral and middle cerebral arteries

Question 10

What happens to the caudal internal carotid artery?

Answer 10

• Anastomoses with caudal communicating artery- branch of basilar

Question 11

Basilar artery anastomoses with what artery?

Answer 11

• Vertebral, receives anastomotic branches from occipital artery

Question 12

What is the rete mirabile?

Answer 12

Arrangement enhances efficiency of blood cooling mechanism

Question 13

What is the metabolic req of the gray matter of the brain?

Answer 13

• 15-20% of CO

Question 14

What is the main structural component of the BBB?

Answer 14

• Composed of tight junctions between endothelial cells of brain caps, so everything aside from small lipid-soluble molecules must be transported through cap endothelium

Question 15

What are the organs not protected by the BBB?

Answer 15

• Subfornical organs
• Pineal body
• Subcommissural organ
• Area postrema
• Posterior and intermediate lobes of pit
• Median eminence
• Vascular organ of lamina terminalis

Question 16

What artery supplies the gray matter of the SC?

Answer 16

• Ventral spinal artery and adjacent white matter

Question 17

What artery supplies the white matter of SC?

Answer 17

• Radial branches from the dosrolateral arteries and surface plexus

Question 18

What is the venous drainage set up?

Answer 18

• Dorsal sag sinus- veins from cerebral hemis
• Joined toward its caudal end by straight sinus - runs within the falx cerebri and collects blood from a major vein drianing deeper parts of brain

Question 19

What happens to the dorsal sag sinus?

Answer 19

• Splits into bilateral transverse sinuses within tentorium cerebelli
• one leaves skull through foramen
• Other one connects with ventral system

Question 20

What drains the ventral system?

Answer 20

• Ventral or basilar system
  Also receives major inflow from a vein that enters the cranial cavity from the orbit

Question 21

What is the rostral part of the long trunk of the ventral system?

Answer 21

• Cavernous sinus: connected with others with rostral and caudal to the hypophysis
• divides caudally into the basilar sinus

Question 22

Why is the blood flow noteworthy into the cranial cavity?

Answer 22

1. Potenital pathway for the spread of infection from face to the cranial contents
2. Cooling to hypothalamus, due to passage of the internal carotid artery through the cavernous sinus where this is surrounded by venous drainage

Question 23

What are the venous channels of neck and trunk that connect to venous plexus via intervertebral foramina?

Answer 23

• Vertebral, cranial caval, azygos and caudal caval veins

Question 24

How are the veins composed?

Answer 24

• Thin walled and without valves
• blood diverted into the vertebral plexus when flow through other channels is impeded may be temp held stagnant