BMB 1 - Cranial Foramina, Meninges, the Ventricular System, CSF, & the Blood-Brain Barrier

Question 1

The cervicomedullary junction (where the medulla oblongata meets the spinal cord) is located where?

Answer 1

The foramen magnum

Question 2

The cranial vault is divided into how many fossae?

Answer 2

Three

(anterior, middle, posterior)

Question 3

Identify the major structures withiin each of the following fossa of the cranial vault:

Anterior -

Middle -

Posterior -

Answer 3

Identify the major structures withiin each of the following fossa of the cranial vault:

Anterior - frontal lobe

Middle - temporal lobe

Posterior - cerebellum; brainstem

Question 4

Name the skull foramina through which each of the following exits the cranial vault:

CN I

CN II

CN III

Answer 4

Cribriform plate

Optic canal

Superior orbital fissure

Question 5

Name the skull foramina through which each of the following exits the cranial vault:

CN IV

CN V₁

CN V₂

Answer 5

Superior orbital fissure

Superior orbital fissure

Foramen rotundum

Question 6

Name the skull foramina through which each of the following exits the cranial vault:

CN V₃

CN VI

CN VII

Answer 6

Foramen ovale

Superior orbital fissure

Internal auditory meatus

Question 7

Name the skull foramina through which each of the following exits the cranial vault:

CN VIII

CN IX

CN X

Answer 7

Internal auditory meatus

Jugular foramen

Jugular foramen

Question 8

Name the skull foramina through which each of the following exits the cranial vault:

CN XI

CN XII

Answer 8

Jugular foramen (Note: the accessory n. entered the skull via the foramen magnum)

Hypoglossal canal

Question 9

Identify the major structure(s) passing through the foramen magnum (nervous, vasculature, etc.).

Answer 9

Medulla oblongata

Vertebral arteries

CN XI roots

Question 10

Identify the major structure(s) passing through the hypoglossal canal (nervous, vasculature, etc.).

Answer 10

CN XII

Question 11

Identify the major structure(s) passing through the jugular foramen (nervous, vasculature, etc.)

Answer 11

CN IX, X, and XI

The internal jugular vein

The inferior petrosal and sigmoid sinuses

Question 12

Identify the major structure(s) passing through the internal acoustic meatus (nervous, vasculature, etc.).

Answer 12

CN VII and VIII

Question 13

Identify the major structure(s) passing through the carotid canal (nervous, vasculature, etc.).

Answer 13

The internal carotid artery

The internal carotid nerve plexus

Question 14

Identify the major structure(s) passing through the foramen spinosum (nervous, vasculature, etc.).

Answer 14

The middle meningeal artery

The meningeal branch of the mandibular nerve

Question 15

Identify the major structure(s) passing through the foramen ovale (nervous, vasculature, etc.).

Answer 15

CN V₃

The lesser petrosal nerve

Question 16

Identify the major structure(s) passing over the foramen lacerum (nervous, vasculature, etc.).

Answer 16

The greater petrosal nerve

Question 17

Identify the major structure(s) passing through the foramen rotundum (nervous, vasculature, etc.).

Answer 17

CN V₂

Question 18

Identify the major structure(s) passing through the superior orbital fissure (nervous, vasculature, etc.).

Answer 18

CN III, IV, V₁, VI

The superior ophthalmic vein

Question 19

Identify the major structure(s) passing through the optic canal (nervous, vasculature, etc.).

Answer 19

CN II

the ophthalmic artery

Question 20

Identify the major structure(s) passing through the cribriform foramina (nervous, vasculature, etc.).

Answer 20

CN I

Question 21

Via what foramina do the lesser and greater palantine neurovasculature exit the cranial vault?

Answer 21

The lesser and greater palantine foramina

(respectively)

Question 22

From external to internal, name the three layers of meninges (and also the two layers of the external layer).

Answer 22

Dura (periosteal and inner meningeal)

Arachnoid

Pia

Question 23

What is the name of the sheet of dura mater that separates the two hemispheres of the brain?

Answer 23

The falx cerebri

(frontally attaches at the crista galli)

Question 24

What is the name of the sheet of dura mater that separates the occipital lobe and the cerebellum?

Answer 24

The tentorium cerebelli

Question 25

What structure separates the supratentorial from the infratentorial brain structures?

Answer 25

The **tentorium cerebelli**

Question 26

The midbrain must pass through an opening in the tentorium cerebelli. What is the opening called?

Answer 26

The **tentorial notch**

Question 27

**True/False**. The dura mater is the tough outer layer. The arachnoid mater is a spider layer beneath which contains the CSF. The pia mater is the imperceptibly thin layer closely covering the brain.

Answer 27

True.

Question 28

The pia mater surrounds the initial portion of each blood vessel as it penetrates the brain surface, forming a space called the __________ space.

Answer 28

The pia mater surrounds the initial portion of each blood vessel as it penetrates the brain surface, forming a space called the **_perivascular_** space ***(****a.k.a. the Virchow-Robin space)***.

Question 29

What is the only significant difference between the cranial meninges and the spinal meninges?

Answer 29

A layer of **epidural fat** in the spinal cord (between the dura and periosteum)

Question 30

The middle meningeal artery runs in what potential space?

Answer 30

The **epidural space** (a pseudospace between dura mater and closely adhered cranium)

Question 31

Name the main blood vessels found in the following meningeal spaces: ## Footnote **Epidural** - **Subdural** - **Subarachnoid** -

Answer 31

Name the main blood vessels found in the following meningeal spaces: ## Footnote **Epidural** - _middle meningeal artery_ (along the pterion) **Subdural** - _bridging veins_ **Subarachnoid** - _major brain arteries_

Question 32

Name the location for the following blood vessels within the meningeal spaces: ## Footnote **Middle meningeal artery** (along the pterion) - **Bridging veins** - **Major brain arteries** -

Answer 32

Name the location for the following blood vessels within the meningeal spaces: ## Footnote **Middle meningeal artery** (along the pterion) - _epidural space_ **Bridging veins** - _subdural space_ **Major brain arteries** - _subarachnoid space_

Question 33

Dural venous sinuses are large venous channels that are enclosed within what space?

Answer 33

Between the **two layers of dura**

Question 34

What is the purple labeled portion of the lateral ventricle called? And the yellow portion?

Answer 34

**Frontal** (or anterior) **horn** ## Footnote **Body**

Question 35

What is the green labeled portion of the lateral ventricle called? And the red portion? And the blue?

Answer 35

**Atrium** **Occipital** (posterior) **horn** **Temporal** (inferior) **horn**

Question 36

The lateral and third ventricles are connected via the foramina of \_\_\_\_\_\_\_\_. The third ventricle is connected to the fourth ventricle via the \_\_\_\_\_\_\_\_.

Answer 36

The lateral and third ventricles are connected via the foramina of **_Monro_**. The third ventricle is connected to the fourth ventricle via the **_cerebral aquaduct_**.

Question 37

The fourth ventricle is drained medially via the foramina of ________ and laterally via the foramina of \_\_\_\_\_\_\_\_. .

Answer 37

The fourth ventricle is drained medially via the foramina of **_Magendie_** and laterally via the foramina of **_Luschka_**. .

Question 38

Where is the third ventricle of the brain located?

Answer 38

Between the left and right thalami

Question 39

The cerebral aquaduct is a small passageway that mainly passes through which general structure?

Answer 39

The midbrain

Question 40

The fourth ventricle is a flaring of the cerebral aqueduct found at the location of the _______ and \_\_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 40

The fourth ventricle is a flaring of the cerebral aqueduct found at the location of the **_pons_** and **_rostral medulla oblongata_**.

Question 41

Does CSF enter or exit the brain via the subarachnoid space?

Answer 41

Exit

Question 42

The reabsorption of CSF occurs in the subarachoid space via arachnoid __________ that absorb the CSF into _____ \_\_\_\_\_ _____ (which drain to the bloodstream).

Answer 42

The reabsorption of CSF occurs in the subarachoid space via arachnoid **_granulations_** that absorb the CSF into **_dural_** **_venous_** **_sinuses_** (which drain to the bloodstream).

Question 43

Adults typically have ~\_\_\_\_\_ mL of CSF at any given time. Adults typically produce ~\_\_\_\_\_ mL of CSF per day.

Answer 43

Adults typically have ~**_150_** mL of CSF at any given time. Adults typically produce ~**_500_** mL of CSF per day.

Question 44

What are the cranial cisterns?

Answer 44

Enclosed spaces serving as **CSF reservoirs**

Question 45

Where is the cisterna magna (the largest of the cisterns)?

Answer 45

Inferior to the cerebellum

Question 46

Where are the paramesencephalic cisterns? Where is the quadrigeminal cistern?

Answer 46

(PC - lateral to the midbrain) (QC - posterior to the midbrain, surrounding the colliculi)

Question 47

Where is the interpeduncular cistern? Where is the prepontine cistern?

Answer 47

(IPC - anterior to the midbrain) | (PPC - anterior to the pons)

Question 48

Which cranial nerve or vasculature can be found in the interpeduncular cistern?

Answer 48

CN III

Question 49

Which cranial nerve or vasculature can be found in the prepontine cistern?

Answer 49

CN VI Basilar artery

Question 50

**True/False**. Cerebral endothelial cells express an extremely high level of leukocyte adhesion molecules greatly facilitating immune cell entry into the CNS.

Answer 50

**False**. Cerebral endothelial cells express an extremely ***low*** level of leukocyte adhesion molecules greatly ***limiting the amount of*** immune cells that enter the CNS

Question 51

What cell type is abundant along the CNS blood vessels and contains contractile proteins to aid in regulating the dilation and constriction of those blood vessels?

Answer 51

**Pericytes** (they also play an important role in angiogenesis, wound healing, and immune cell regulation)

Question 52

**True/False**. Pericytes can serve as multipotent stem cells for the CNS.

Answer 52

**True**.

Question 53

Astrocytes contain a discrete array of proteins such as \_\_\_\_\_\_\_\_\_\_\_, \_\_\_\_\_\_\_\_\_\_\_, and \_\_\_\_\_\_\_\_\_\_\_.

Answer 53

Astrocytes contain a discrete array of proteins such as **_dystroglycan_**, **_dystrophin_**, and **_aquaporin 4_**.

Question 54

The astrocyte **dysroglycan–dystrophin** complex is important to link the end feet cytoskeleton to the basement membrane by binding \_\_\_\_\_\_.

Answer 54

The astrocyte **dysroglycan–dystrophin** complex is important to link the end feet cytoskeleton to the basement membrane by binding **_agrin_**.

Question 55

Why do astrocytes contain a large amount of aquaporin₄?

Answer 55

CNS water regulation

Question 56

**True/False**. Pericytes are involved in relaying signals to blood vessels and astrocytes to regulate constriction and dilation.

Answer 56

**False**. ***Astrocytes*** are involved in relaying signals to blood vessels and ***pericytes*** to regulate constriction and dilation.

Question 57

The capillaries of the choroid plexus are freely permeable, but the _________ \_\_\_\_\_\_\_\_\_ cells form a barrier between the capillaries and the CSF.

Answer 57

The capillaries of the choroid plexus are freely permeable, but the **_choroid_** **_epithelial_** cells form a barrier between the capillaries and the CSF.

Question 58

Areas where the blood-brain barrier is interrupted are known as ____________ organs.

Answer 58

Areas where the blood-brain barrier is interrupted are known as **_circumventricular_** organs.

Question 59

Name a few circumventricular organs (areas where the blood-brain barrier is interrupted).

Answer 59

**Median eminence**, **neurohypophysis**; **area** **postrema**; **organum** **vasculosum**; **pineal** gland; subcomissural organ

Question 60

Where is the area postrema located?

Answer 60

The **caudal wall** of the **fourth ventricle** | (in the medulla)

Question 61

How much can a normal human increase their absorption of CSF before there is an increase in intracranial pressure? a. None b. 2 times c. 3 times d. 6 times e. 10 times

Answer 61

a. None b. 2 times c. 3 times **d. 6 times** e. 10 times

Question 62

A defect in which of the following would affect the permeability of the blood-brain barrier the most? a. Keratin b. Collagen c. Cadherin d. Occludin e. Myelin

Answer 62

d. Occludin

Question 63

Which of the following can modify the composition of CSF? Select all that apply. a. The dura mater b. The arachnoid mater c. The choroid plexus d. A state of dehydration e. Chronic hypertension

Answer 63

a. The dura mater **b. The arachnoid mater c. The choroid plexus d. A state of dehydration e. Chronic hypertension**

Question 64

Where would you expect find the choroid plexus? Select all that apply. a. In the lateral ventricles b. In the diencephalon c. In the dural sinuses d. In the fourth ventricle

Answer 64

**a. In the lateral ventricles** b. In the diencephalon c. In the dural sinuses **d. In the fourth ventricle**

Question 65

Which barrier would you expect to allow the most freedom of substrate passage? a. Across capillaries into brain parenchyma b. Across capillaries and choroid epithelial cells into CSF c. Across ependymal cells into brain parenchyma

Answer 65

a. Across capillaries into brain parenchyma **b. Across capillaries and choroid epithelial cells into CSF** c. Across ependymal cells into brain parenchyma

Question 66

The fourth ventricle lies between what structures?

Answer 66

The **pons** and **cerebellum**

Question 67

In what location(s) is CSF made?

Answer 67

The _superior and inferior choroid plexi_ in the **lateral and third ventricles**

Question 68

CSF cushions the brain (and spinal cord) mainly through its presence in what space?

Answer 68

The **subarachnoid** space

Question 69

Where is the main location in which arachnoid granulations are found?

Answer 69

The superior sagittal sinus

Question 70

The arachnoid granulations are \_\_\_\_\_\_-way valves driven by \_\_\_\_\_\_\_\_\_\_.

Answer 70

The arachnoid granulations are **_one_**-way valves driven by **_pressure_**.

Question 71

Describe the general make-up of CSF as a hyperfiltrate (in terms of electrolytes, protein levels, cellular presence, glucose levels, etc.).

Answer 71

**High chloride**; **low protein**, **almost no cells**, **low glucose** (60% of serum levels)

Question 72

What are the two most sensitive tests (in order) for a subarachnoid hemorrhage?

Answer 72

(1) **LP** (2) **Head CT**

Question 73

Name the purpose of the four tubes taken in a lumbar puncture.

Answer 73

Tube 1 - **Cell count + differential** Tube 2 - **Protein + glucose** Tube 3 - **I****nfectious studies** (Gram studies, PCRs, cultures, inflammatory markers, etc.) Tube 4 - **Cell count + differential again** (involved in screening for subarachnoid hemorrhage)

Question 74

Cell count and differential is seen in which tube(s) in a lumbar puncture?

Answer 74

Tubes 1 and 4

Question 75

Protein and glucose is seen in which tube in a lumbar puncture?

Answer 75

Tube 2

Question 76

Infectious studies are performed on which tube in a lumbar puncture?

Answer 76

Tube 3

Question 77

What two conditions, if suspected, warrant an especially urgent lumbar puncture?

Answer 77

**CNS infection** (especially in the immunocompromised) **Subarachnoid hemorrhage** (with negative CT scan)

Question 78

Name two general contraindications to lumbar puncture.

Answer 78

Risk for **cerebral herniation** (due to the increased ICP) **Bleeding** issues (thrombocytopenia, anticoagulant use, etc.)

Question 79

What is an archaic term for idiopathic intracranial hypertension?

Answer 79

Pseudotumor cerebri

Question 80

Name two general methods (procedural and pharmacological) for treating intracranial hypertension.

Answer 80

**Lumbar** **puncture** **Carbonic anhydrase** inhibitors

Question 81

Intracranial hypotension is typically seen following what?

Answer 81

Some procedure (e.g. LP)

Question 82

You see neutrophils in a patient's CSF. What does this indicate?

Answer 82

Bacterial meningitis

Question 83

You see lymphocytes in a patient's CSF. What does this indicate?

Answer 83

Viral meningitis

Question 84

Bacterial meningitis is indicated by _________ in the CSF. Viral meningitis is indicated by _________ in the CSF.

Answer 84

Bacterial meningitis is indicated by **_neutrophils_** in the CSF. Viral meningitis is indicated by **_lymphocytes_** in the CSF.

Question 85

Lumbar puncture shows a high number of RBCs in tube 1 only. What does this indicate?

Answer 85

**Traumatic tap** | (high count in 1; low in 4)

Question 86

Lumbar puncture shows a high number of RBCs in tube 1 and tube 4. What does this indicate?

Answer 86

**Subarachnoid hemorrhage** *(can also be seen in HSV encephalitis)*

Question 87

Most CNS infections show _________ CSF protein.

Answer 87

Most CNS infections show **_elevated_** CSF protein.

Question 88

Besides infectious etiologies, what two immune disorders are associated with elevated CSF protein?

Answer 88

**Guillain-Barré** syndrome **Acute inflammatory demyelinating polyradiculoneuropathy** (AIDP) *(NOTE: CSF WBCs are low in these demyelinating disorders.)*

Question 89

Guillain-Barré syndrome and acute inflammatory demyelinating polyradiculoneuropathy (AIDP) are associated with __________ CSF protein and __________ CSF WBCs.

Answer 89

Guillain-Barré syndrome and acute inflammatory demyelinating polyradiculoneuropathy (AIDP) are associated with **_elevated_** CSF protein and **_low_** CSF WBCs.

Question 90

A low-glucose tap (in an infectious meningitis setting) is likely _______ meningitis.

Answer 90

A low-glucose tap is likely **_TB_** meningitis *(due to reactivation)*.

Question 91

**True/False**. Immunoglobulin is not produced within the CSF but must be transported over from the serum.

Answer 91

**False**. Immunoglobulin ***is produced*** within the CSF.

Question 92

Immunoglobulin produced in the CSF will lead to an increased quotient relative to what?

Answer 92

Albumin

Question 93

What causes the oligoclonal bands sometimes seen on protein gel electrophoresis?

Answer 93

IgG found in CSF but not serum

Question 94

Name three major causes of oligoclonal bands.

Answer 94

**Multiple** **sclerosis**, neurosarcoidosis, CNS lupus