Cranial Cavity and Meninges

Question 1

Why is a fracture of the pterion a life threatening concern?

Answer 1

It over lies the middle meningeal vessels

Question 2

Why is a bleed of the middle meningeal such a big deal?

Answer 2

The resulting hemotoma exerts pressure on the underlying cerebral cortex.

Question 3

What is thrombophlebitis of the facial vein? Why is it a concern?

Answer 3

Inflammation of the facial vein with secondary clot formation. It may cause blood of the face to drain through the opthalmic/deep facial veins to the interior of the skull. This could allow infection to spread and trigger thrombophlebitis of the cavernous sinus.

Question 4

How may the facial veins become infected?

Answer 4

Lacerations to the nose, popping zits on the nose/upper lip

Question 5

Because of the propensity to allow infection into the brain, what is the triangular area from the upper lip to the bridge of the nose called?

Answer 5

The Danger Triangle of the Face

Question 6

A fracture of the cranial base usually results in…

Answer 6

dura tears and CSF leaks

Question 7

What is the innermost part of the dura? What cells comprise it?

Answer 7

The Dural Border Cell Layer

Flattened Fibroblasts Separated by Large Extracellular Spaces

Question 8

Why care about the dural border cell layer?

Answer 8

This layer constitutes a plane of structural weakness at the dura-arachnoid junction.

Question 9

Problem with space occupying lesions of the supratentorial compartment?

Answer 9

They increase intracranial pressure, protentiall causing part of the adjacent temporal lobe to herniate through the tentorial notch.

Question 10

So what? A temporal lobe through the tentorial notch? Why care?

Answer 10

The temporal nerve may be lacerated by the tentorium cerebelli and the oculomotor nerve may be stretched/compressed. CN 3 lesions may paralyze eye muscles.

Question 11

How do pituitary tumors tend to expand?

Answer 11

Superiorly through the aperture of diaphragm sellae or cause the diaphragm to bulge.

Question 12

How could a pituitary tumor influence vision?

Answer 12

Pressure on the optic chaism, where the optic nerve fibers cross.

Question 13

What might cause occlusion of cerebral veins/dural sinuses?

Answer 13

Thrombi, Thrombophlebitis, or tumors

Question 14

What dural sinuses are most likely thrombosed?

Answer 14

Transverse, Cavernous, Superior Sagittal.

Question 15

Where do cavernous sinus thromboses tend to come from?

Answer 15

Infections of the orbit, nasal sinuses, or the danger triangle.

Question 16

Thrombophlebitis of he cavernous sinus may affect which nerve?

Answer 16

Abducent

Question 17

Septic thrombosis of the cavernous sinus often results in…

Answer 17

Acute Meningitis

Question 18

How can cancer/infection get to the brain from the thorax/abdomen/pelvis?

Answer 18

Venous Blood –> Internal Vertebral Venous System –> Dural Venous sinuses

No valves on these veins

Pus and tumor cells may spread freely through this route.

Question 19

In fractures of the cranial base, what artery should you be concerned about?

Answer 19

ICA

Question 20

A torn ICA will cause…

Answer 20

An Arteriovenous fistula within a cavernous sinus (in which arterial blood rushes into the cavernous sinus, enlarging it, and forcing retrograde bloodflow.

Question 21

Side effect of an arteriovenous fistula?

Answer 21

Eyeball protusion (exophthalmos) and Engorged conjunctiva (chemosis)

Question 22

Define Pulsating Exphthalmos.

Answer 22

The eyeball pulsates in synchrony with the radial pulse.

Question 23

In an arteriorvenous fistula, what nerves do you need to worry most about?

Answer 23

3, 4, V1, V2, 6

Question 24

One major cause of headaches is…

Answer 24

Pulling on arteries at the cranial base of veins near the vertex, where they pierce the dura.

When CSF is removed, the brain sags slightly, pulling on dura.

Question 25

What is leptomeningitis?

Answer 25

Inflammation of the arachnoid and pia resulting from pathogenic organisms.

Question 26

In leptomeningitis, where are the infection and inflammation?

Answer 26

Subarachnoid Space and arachnoid-pia.

Question 27

How do bacteria get into the CSF?

Answer 27

Through the blood or spread from an infection of the heart, lungs, or other viscera. ALso, through a compound cranial fracture or fracture of nasal sinuses.

Question 28

Cause of Acute Purlent Meningitis?

Answer 28

Infection with almost any pathogenic bacteria (ex. meningococcal meningitis)

Question 29

Extradural/Epidural Hemorrhage – Origin, location, what happens

Answer 29

Middle Meningeal Artery
btw dura and calveria
Tends to strip dura from cranium, hematoma, concussion, eventually pressure will build up to a coma

Question 30

Subdural hematoma - tell me everything.

Answer 30

Typically Superior Cerebral Vein as it enters Sagittal sinus
btw arachnoid and dura (normally nonexistent space)
Typically from a hard blow/jerk of head. No major side effects

Question 31

Subarachnoid hemorrhage – tell me everything.

Answer 31

Arterial Blood into the subarachoid space (probs from rupture of a saccular aneurysm.
Causes meningeal irritation, headache, stiff neck, and unconsciousness.