Brain, brainstem, meninges, and ventricles

Question 1

What are the lobes of the brain?

Answer 1

frontal, parietal, temporal, occipital lobe, insular lobe (frontal and temporal lobes pulled back to view insular)

Question 2

What are the three subregions of the brainstem?

Answer 2

-midbrain
-pons
-medulla

Question 3

What is the ventricular system?

Answer 3

Network of cavities in the brain and spinal cord which produce and circulate CSF

Question 4

What are the structures of the ventricular system?

Answer 4

-R&L Lateral ventricles: connected (CSF flows from these to third ventricles

-third ventricle: CSF flows toward brainstem and into fourth ventricle

-fourth ventricle

-choroid plexus: specialized cells in each venticles that produce CSF

Question 5

What is the function of CSF (cerebral spinal fluid)?

Answer 5

Interstitial fluid of CNS, serves as a physical fluid barrier to protect the central nervous system

Question 6

What is the pathway of CSF?

Answer 6

-CSF is produced in the choroid plexus
-CSF flows from the lateral ventricles into the third ventricle and then to the fourth ventricle
-fourth ventricle will send CSF down to the spinal chord
-CSF will also flow out of the ventricular system into the subarachnoid space where it continues to circulate into the arachnoid space and granulations
-from the arachnoid granulations the CSF will enter the dural sinus and drain to the bottom of the skull to the IJV

Question 7

What are the three meningeal folds?

Answer 7

-dura: outer tough connective tissue (adheres to bone of skull)

-arachnoid: middle layer, contains CSF

-pia: innermost layer, follows every sulci and gyri contour of the brain

Question 8

What are the two layers of the dura?

Answer 8

-periosteal layer: outer, merges with the skull

-meningeal layer: inner, forms dural folds

For dura:
**can see on cadaver image: meningeal arteries embedded in the dura
**cannot see on cadaver image: cerebral blood vessels or sulci/gyri of brain

Question 9

What are arachnoid trabeculae?

Answer 9

Connections of the arachnoid that anchor to the pia layer (give space and support for cerebral blood vessels to flow along the contours)

For arachnoid:
**can see on cadaver image: cerebral blood vessels in subarachnoid space that follow the sulci
**looks very glossy and smooth over sulci

Question 10

What can you see on the pia layer on a cadaver image?

Answer 10

Countours of the sulci and gyri

***usually cannot cannot see: blood vessels

Question 11

What are the dural folds? What do they create?

Answer 11

-falx cerebri: vertical, divides L&R cerebrums (hemispheres)

-tentorum cerebelli: “floor subdivider” (lays flat around circle of the back of the skull), divides cerebellum from the rest of the brain (hemispheres)

-falx cerebelli: small dural fold that divides R&L and runs along the back of the cerebellum (kind of a continuation of falx cerebri)

***Dural folds create subdivisions of the skull

Question 12

What are cerebral hematomas? What are the types of cerebral hematomas?

Answer 12

Blood vessel rupture causing blood to accumulate in the meningeal spaces (forming a hematoma)

Types
Epidrual: hematoma in space between periosteal layer of the dura and the bone, pushes the dura inward

Subdural: hematoma in space between dura and arachnoid layers

Subarachnoid: hematoma in space between arachnoid and pia layers (CSF flows here)

Question 13

What causes an epidural hematoma?

Answer 13

Blood accumulating between the bone and periosteal layer of the dura

-caused by rupture of meningeal arteries

**trauma to the pterion may cause damage or rupture of the middle meningeal artery and cause an epidural hematoma

THESE DO NOT CROSS SUTURE LINES
periosteal dura anchors tightly to portions of the skull (difficult to separate beyond the individual bone to which it adheres)

Question 14

What causes a subdural hematoma?

Answer 14

Blood accumulating between the dura and subarachnoid layers

-caused by rupture of bridging veins (veins which cross the subdural space in order to connect to venous sinuses and drain into the IJV for venous return)

-High mortality (60-80%)/emergent concern

THESE DO CROSS SUTURE LINES
the subdural space is continuous, you don’t have the same anchoring anatomy as the periosteal dura (so blood will continue to pool to different areas of the head)

Question 15

What causes a subarachnoid hemorrhage?

Answer 15

Blood accumulates in the CSF between the arachnoid and pia layers

-caused by cerebral artery ruptures that happen due to saccular “berry” aneurysms located around the circle of willis (at junctions the arterial wall will begin to balloon out and rupture)

***Usual complaint: “worst headache of my life!”