Cranial Cavity and Meninges Flashcards
Why is a fracture of the pterion a life threatening concern?
It over lies the middle meningeal vessels
Why is a bleed of the middle meningeal such a big deal?
The resulting hemotoma exerts pressure on the underlying cerebral cortex.
What is thrombophlebitis of the facial vein? Why is it a concern?
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.
How may the facial veins become infected?
Lacerations to the nose, popping zits on the nose/upper lip
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?
The Danger Triangle of the Face
A fracture of the cranial base usually results in…
dura tears and CSF leaks
What is the innermost part of the dura? What cells comprise it?
The Dural Border Cell Layer
Flattened Fibroblasts Separated by Large Extracellular Spaces
Why care about the dural border cell layer?
This layer constitutes a plane of structural weakness at the dura-arachnoid junction.
Problem with space occupying lesions of the supratentorial compartment?
They increase intracranial pressure, protentiall causing part of the adjacent temporal lobe to herniate through the tentorial notch.
So what? A temporal lobe through the tentorial notch? Why care?
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.
How do pituitary tumors tend to expand?
Superiorly through the aperture of diaphragm sellae or cause the diaphragm to bulge.
How could a pituitary tumor influence vision?
Pressure on the optic chaism, where the optic nerve fibers cross.
What might cause occlusion of cerebral veins/dural sinuses?
Thrombi, Thrombophlebitis, or tumors
What dural sinuses are most likely thrombosed?
Transverse, Cavernous, Superior Sagittal.
Where do cavernous sinus thromboses tend to come from?
Infections of the orbit, nasal sinuses, or the danger triangle.
Thrombophlebitis of he cavernous sinus may affect which nerve?
Abducent
Septic thrombosis of the cavernous sinus often results in…
Acute Meningitis
How can cancer/infection get to the brain from the thorax/abdomen/pelvis?
Venous Blood –> Internal Vertebral Venous System –> Dural Venous sinuses
No valves on these veins
Pus and tumor cells may spread freely through this route.
In fractures of the cranial base, what artery should you be concerned about?
ICA
A torn ICA will cause…
An Arteriovenous fistula within a cavernous sinus (in which arterial blood rushes into the cavernous sinus, enlarging it, and forcing retrograde bloodflow.
Side effect of an arteriovenous fistula?
Eyeball protusion (exophthalmos) and Engorged conjunctiva (chemosis)
Define Pulsating Exphthalmos.
The eyeball pulsates in synchrony with the radial pulse.
In an arteriorvenous fistula, what nerves do you need to worry most about?
3, 4, V1, V2, 6
One major cause of headaches is…
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.
