4 - Meninges & Dural Venous Sinuses Flashcards
Describe the payer of dura mater and how it related to spinal nerves?
Dura mater is over the dorsal root ganglia and comes to the spinal nerve where it interdigitates with the outer covering of the nerves.
How does epidural anesthesia work?
It runs along the dura until it reaches the spinal nerve distally.
Where does spinal anesthesia have its affect? What is an important thing to considering when administering spinal anesthesia?
It is in the CSF of the subarachnoid space.
Keep them sitting up so the substances doesn’t get to the brain.
What are the air-filled sinuses of the brain?
Maxillary sinus, frontal sinus, and sphenoid sinus.
Where are dural venous sinuses located?
Blood-filled sinuses between the periosteal and meningeal layers of the dura mater.
What is the function of the dorsal venous sinuses?
Bring venous blood back to CV.
CSF from the arachnoid granulations will also flow into the dorsal venous sinuses.
What vessel is deep to the pterion? What is this vessel a branch of and what is its path?
The middle meningeal artery, a branch of the maxillary artery, heads superiorly through the foramen spinosum.
What are the two classification of veins found in the head?
Emissary veins (diploid) - work their way through the skull and connects superficial to deep structures and drain some of the sinuses.
Cerebral veins (bridging veins) - delicate and go through the dura mater and go into the dural venous sinuses.
What is the clinical significance of cerebral (bridging) veins?
They are delicate and go through the dura mater.
They can be torn during car accidents causing ripping in the subarachnoid space. Bleeding here will compress the brain and pressure will build.
What are leptomeninges? What is leptomeningitis?
The pia and arachnoid mater.
Infection of the CSF, which is in between the pia and arachnoid mater.
What nerve innervates the dura mater? Describe the distribution?
The trigeminal nerve.
V1 goes forward to innervate the orbit and back to innervate the orbit.
V2 lower eyelid and upper lip
V3 lower lip and jaw
What are the three parts of the temporal bone?
Squamous (high), tympanic part (around the eardrum), and the petrous (hard) part.
What veins feed into the cavernous sinus?
The superior opthalmic vein and the superior petrosal sinus.
The superior opthalmic connects to the angular and superficial veins at the superficial parts of the face.
What vessels are at the edges of the falx cerebri?
Superior and inferior saggital sinuses.
The straight sinus connects to the superior saggital sinus and transverse sinuses at the confluence of sinus.
What cranial nerves go through the jugular foreamen?
CN 9, 10, and 11.
What does the angular vein turn into? At what point does this occur?
The angular vein becomes the facial vein at the bottom of the orbital rim.
What is connected to the facial vein and leads to the cavernous sinus?
The pterygoid venous plexus.
What vein is superficial to the SCM in the neck? What vein is deep to it?
External jugular vein is superficial to the SCM.
Internal jugular vein is deep to it.
What are the tributaries of the facial vein?
- Angular: supraorbital, supratrochlear, external nasal
- Superior labial
- Deep facial
- Inferior Labial
- Tonsillar
- Submental
- Submandibular
What tributaries of the facial vein are in the danger zone of the face? Why is this region called the danger zone?
Angular: supraorbital
Superior Labial
Deep facial
Inferior labial
Infections here go directly back to the cavernous sinus
What are the superficial venous connections to the cavernous sinus?
The superior opthalmic (from angular) and the inferior opthalmic. veins.
What blood vessels and nerves are located in the cavernous sinus?
CN’s 3, 4, V1, V2, and 6
O CAT O M
Oculomotor nerve Trochlear Nerve Opthalmic branch of trigeminal nerve Maxillary branch of trigeminal Carotid (internal) artery Abducens Trochlear nerve
What other structures (besides artery and nerves) are located in the cavernous sinus?
The pituitary and the optic chiasm.
What is an early warning sign of a blood clot in the cavernous sinus? What happens if it worsens?
Clot will contrict down on itself and compress CN 6 (abducent n), causing double vision.
Next it will compress CN 3 (oculomotor) and it will be difficult to open eyes; eyeball pinned down and out.
CN 4 next.
Then V1 and V2 causing stabbing pain in corresponding dermatomes.
What bone meet at the pterion?
The frontal, parietal, temporal, and sphenoid bones.
What causes a lensticular hematoma?
Rupture of the middle meningeal artery, which causes an epidural bleed that dissects the periosteal layer from the skull itself until it reaches a suture.
What can occur if cerebral arteries tear and bleed into the subarachnoid space.
The build up of pressure from the blood can cause the brain to herniate down through the foramen magnum (central).
What happens if bridging veins tear?
Blood will flow into the epidural area but will be low pressure and the hematoma will be smaller than seen with arterial bleeds.
