Lesson 2: Coverings & Spaces of the CNS

Question 1

What type of cells create CSF?

Answer 1

Specialized ependymal cells

Question 2

Where is CSF produced?

Answer 2

In the choroid plexus

Question 3

How does CSF get from the lateral ventricles to the 3rd ventricle?

Answer 3

The interventricular foramen of Monroe

Question 4

How does CSF get from the 3rd ventricle to the 4th?

Answer 4

The cerebral aqueduct

Question 5

How does CSF get from the 4th ventricle to the subarachnoid space? What happens to a small amount?

Answer 5

The foramina of Luschka and the foramen of Magendie. A small amount exits into the central canal of the spine

Question 6

What is the choroid plexus made of? What are its three layers?

Answer 6

It is made of a network of infolded vascular capillaries. It is covered by pia mater and connective tissue, which are then lined by an epithelium layer

Question 7

What are the four parts of the lateral ventricles? What separates them?

Answer 7

A body, and three horns: anterior, posterior, inferior. The septum pellucidum is located between the anterior ventricular horns

Question 8

What structures are above and below the lateral ventricles?

Answer 8

Above: corpus callosum
Below: thalamus

Question 9

Where is the third ventricle located? What is at its floor?

Answer 9

Between the two thalami, with the hypothalamic nuclei at its floor

Question 10

Where is the cerebral aqueduct located? Which ventricles does it connect?

Answer 10

It separates the tectum and the tegmentum in the midbrain. It connects the 3rd and 4th ventricle

Question 11

Where is the fourth ventricle located?

Answer 11

Roof: cerebellum
Floor: pons and medulla

Question 12

How are the connections between the fourth ventricle and the subarachnoid space located? What are their names?

Answer 12

Laterally: the foramina of Luschka (2)
Medially: foramen of Magendie (1)

Question 13

Where is the subarachnoid space located? What is inside of it - both for irrigation and waste removal?

Answer 13

Between the arachnoid membrane and pia mater. It houses cisterns, and all the smaller blood vessels for the brain

Question 14

What is a perivascular space?

Answer 14

Site for possible diffusion of metabolic solutes from the CSF into extracellular fluid (cysts)

Question 15

What are arachnoid granulations? Where are they located?

Answer 15

They absorb CSF. They are part of the arachnoid membrane that sticks into the dura mater. They are located dorsally bilaterally along the superior sagittal sinus, which they empty CSF into

Question 16

What is required for the emptying of arachnoid granulations?

Answer 16

A pressure difference - the sinus pressure must be below the pressure of the ventricles, otherwise the arachnoid villi close

Question 17

What are the four causes of lesions in the ventricular system?

Answer 17

Excess fluid production
Tumours actually blocking the space
Blockage of the cerebral aqueduct
Diminished absorption

Question 18

What is the most common type of lesion of the ventricular system after brain injury?

Answer 18

Diminished absorption of CSF

Question 19

What are meninges? What are they made of?

Answer 19

The layers over the brain after the skull. Made of connective tissue

Question 20

What is connective tissue made of?

Answer 20

Fibrous sheets made by fibroblasts

Question 21

What are the three meninges layers of the brain?

Answer 21

Outermost: dura mater
Middle: arachnoid mater
Innermost: pia mater

Question 22

What are the two dura mater layers?

Answer 22

Periosteal and meningeal

Question 23

What qualities are specific to the dura mater?

Answer 23

Is has a rich vascular supply and sensory innervation
It is dense
Is has two layers

Question 24

What is the periosteal dura mater?

Answer 24

Lines the skull internally

Question 25

What is the falx cerebri?

Answer 25

Where the meningeal dura mater extends into the longitudinal fissure to separate the cerebrum's hemispheres

Question 26

What is the tentorium cerebelli?

Answer 26

Horizontal infolding of the meningeal dura mater that separates the cerebellum and the cerebrum

Question 27

What is the falx cerebelli?

Answer 27

Meningeal dura mater that separates the cerebellum into two hemispheres below the tentorium cerebelli

Question 28

What occurs in the space where the periosteal and meningeal dura mater layers separate?

Answer 28

The sinuses

Question 29

What is the subdural space? What does it contain?

Answer 29

Between the visceral (innermost) dura mater layer and the arachnoid mater. It contains a few cerebral veins

Question 30

What is the arachnoid mater like? Where is it located

Answer 30

Between the subdural space and the pia mater. It is like plastic wrap

Question 31

What is the structure of the pia mater? What feature is unique to it?

Answer 31

It is a single cell layer directly on brain tissue that follows all infoldings. It is permeable, and thus allows for the passage of small vessels into the brain tissue

Question 32

What is the anterior cranial fossa located over?

Answer 32

The frontal lobe | The nasal cavity and orbits

Question 33

What is the posterior cranial fossa contain?

Answer 33

The cerebellum

Question 34

What is the foramen magnum?

Answer 34

The hole through which the spinal cord exits the skull

Question 35

Where is the sphenoid bone located?

Answer 35

Behind the eye

Question 36

Where is the zygomatic arch located? What does it connect?

Answer 36

Over the temple. It connects the zygomatic bone (cheekbone) to the temporal bone

Question 37

Where is the pterion located?

Answer 37

It attaches the parietal bone and the sphenoid bone

Question 38

Where is the external acoustic meatus?

Answer 38

Behind and below the zygomatic arch, directly below the temporal bone

Question 39

Where is the styloid process?

Answer 39

Anterior to the mastoid process, below the ear

Question 40

Where is the mastoid process?

Answer 40

Posterior to the styloid process, below the ear

Question 41

Where is the internal acoustic meatus?

Answer 41

The interior part of the eardrum

Question 42

Where is the foramen rotundum? What exits from it?

Answer 42

It is in the floor of the middle cranial fossa. It is the exit point of the maxillary nerve (a branch of the trigeminal nerve)

Question 43

Where is the foramen ovale? What exits from it - both a nerve and an artery

Answer 43

It is in the floor of the middle cranial fossa. It provides passage for the mandibular nerve (from the trigeminal nerve) and the accessory meningeal artery

Question 44

Where is the carotid canal? What enters through it?

Answer 44

Anteromedial to the styloid process. It allows the internal carotid artery in

Question 45

Where is the foramen spinosum? What artery enters through it?

Answer 45

It is posterior-lateral to the foramen ovale. It allows through the middle meningeal artery and the meningeal branch of the mandibular nerve

Question 46

Where is the jugular foramen located? What nerves pass through it, and what venous structures?

Answer 46

It is immediately inferior to the internal acoustic meatus. The glossopharyngeal, vagus and accessory nerve all pass through it. The internal jugular vein also does.

Question 47

What arteries supply the brain? (4)

Answer 47

Left and right internal carotid arteries and vertebral arteries

Question 48

What venous sinuses drain the venous blood from the brain?

Answer 48

Left and right internal jugular veins

Question 49

What is an arteriovenous malformation?

Answer 49

A blood vessel abnormality, where the blood flows directly from arteries to veins without a pressure-reducing capillary bed

Question 50

What is a sign of oculomotor nerve damage? Why does this occur?

Answer 50

Since the oculomotor nerve carries info to constrict the pupil - the pupil is thus constantly dilated (big)

Question 51

What is an aneurysm, and what is its consequence?

Answer 51

A large defect in the blood vessel. It causes pressure on brain tissue and the adjacent blood vessels

Question 52

Where does the brain swell to if it swells sideways?

Answer 52

Against the falx cerebri

Question 53

Where does the brain swell if it swells downward? What can is push that can be deadly?

Answer 53

To the anterior portion of the tentorium cerebelli. It can push the tonsil of the cerebellum through the foramen magnum, which puts pressure on the medulla