Nervous System Part 4 (Cont.) Flashcards
Superficial Cerebral Veins
Dural Venous Sinuses
Internal Jugular Vein
CNS Venous Circulation
Run in the subarachnoid space. Right before they terminate to drain into the Superior Sagittal Sinus, they pierce the Arachnoid membrane and enter the Subdural Space.
-Subdural hematomas occur on either side of the Superior Sagittal Sinus.
Superficial Cerebral Veins
Found in the upper portion of the Falx Cerebri.
-Formed by a rolled up sleeve of Dura Mater
Superior Sagittal Sinus
Found along the free edge of the Falx Cerebri.
-Formed by a rolled up sleeve of Dura Mater
Inferior Sagittal Sinus
Venous structure that drains deep subcortical structures, such as the Thalamus and Basal Ganglia
Great Cerebral Vein of Galen
Formed by the convergence of the Inferior Sagittal Sinus and the Great Cerebral Vein of Galen.
Straight Sinus
Runs in the Falx Cerebelli. Drains blood into the sinus system from the Cerebellum.
Occipital Sinus
Occipital region where all of the dural sinuses come together.
-Deep to the Occiput (Occipital Protuberance)
Confluence of Sinuses
Moves laterally out of the Confluence of sinuses; one on each side
Transverse Sinus
Formed by the Transverse Sinus; terminates in the IJ as it passes through the Jugular Foramen. Blood is returned to the heart.
Sigmoid Sinus
A venous lake formed by dura mater, found on either side of the Sphenoid Bone.
-Receives drainage from the Superior Ophthalmic Vein (front- drains orbit) and the Sphenoparietal Sinus (runs along the lesser wing of the sphenoid bone).
-Drains into the Superior and Inferior Petrosal Sinuses
Cavernous Sinus
Sinuses running along the Petrous portion of the Temporal Bone (Apex = Superior; Base = inferior) that drain the Cavernous sinuses.
-Drain into the Sigmoid Sinus as it is being formed (Superior) or as it is preparing to enter and drain into the IJ at the Jugular Foramen (Inferior)
Superior or Inferior Petrosal Sinuses
Joins the two Cavernous sinuses together in the middle
-Contains the Pituitary gland.
Intercavernous Sinus
Contains:
-CN III (Upper, outer corner)
-CN IV (just below CN III, very edge of sinus)
-CN VI (right below internal carotid)
-CN V: Ophthalmic and Maxillary Divisions
-Int. Carotid Artery (passes through as it merges into the cranial cavity)
Cavernous Sinus
Infection in Cranial Cavity can get into Cavernous Sinus, occluding blood flow into the sinuses, increasing pressure, compressing structures.
-Pupil Dilation
-Affected sensation to Upper 1/3 of face, forehead to crown (Ophthalmic) and middle 1/3 of face (Maxillary).
-Facial Numbness
Cavernous Sinus Dysfunction
Network of veins lying deep to the mandible (ramus).
-Lying in the Infratemporal Fossa
-Overlies pterygoid plates
-Receives venous drainage from Ophthalmic veins (Superior and Inferior Ophthalmic veins drain the orbit), and the Cavernous Sinus via Emissary Veins that penetrate the bone.
-Blood flows from inside to outside. Still risk for infection if infection on side of the face (could still go retrograde against the flow, into the cranial cavity, especially in cavernous sinus)
Pterygoid Plexus of Veins
Drain the Ophthalmic veins, veins making up the pterygoid plexus, and the Cavernous Sinuses.
-Connect the Cavernous sinuses with the pterygoid plexus of veins.
-Pierce the bone to exit the skull
Emissary Veins
Drain the Ophthalmic veins, veins making up the pterygoid plexus, and the Cavernous Sinuses.
-Connect the Cavernous sinuses with the pterygoid plexus of veins.
-Pierce the bone to exit the skull
Emissary Veins
Provides nutrition to neurons and glial cells
Provides mechanical support to protect the brain and CNS
-Avg volume in adults is 150-200 mL
CSF
Produce CSF in all Ventricles.
-Tufts of capillaries covered by ependymal cells
Choroid Plexus
One in each cerebral hemisphere.
1)Anterior horn: frontal parts running in cerebral cortex
2) Posterior Horn: tail that extends back into posterior portion of the brain (occipital)
3) Inferior Horn: curves around to make C-Shape, runs in temporal lobe
Lateral Ventricles
Communication between lateral ventricles and 3rd ventricle. Allows CSF produced in the lateral ventricles to flow down into the 3rd ventricle.
Interventricular Foramen of Monro
Tissue running from brainstem to cerebellum. Has a little opening called the Dorsomedian Aperture (Foramen of Magendie). This aperture communicates the 4th ventricle with subarachnoid space. Allows for CSF to flow down from the 4th ventricle into subarachnoid space.
Inferior Medullary Velum
Very small openings on either side of the 4th ventricle that communicate 4th ventricle with subarachnoid space as well.
Lateral Foramina
Causes scarring around aperture - it shrinks. Have backlog of CSF. CSF accumulates, causing hydrocephalus.
-Any obstruction in flow of CSF can potentially cause hydrocephalus. CSF is still being produced, so it just backs up and fills the ventricles.
Meningitis
A little opening that communicates the 4th ventricle with a large space that is lying beneath the cerebellar overhang (cerebellum hangs down over dorsal aspect of the brainstem).
-CSF exits via the Dorsomedian Aperture (Foramen of Magendie)
-Enlarged Subarachnoid Space continuous with the rest of the Subarachnoid space.
Cisterna Magna
Lying just underneath the Corpus Callosum.
-A cluster of fibers from the Hippocampus
-Has columns that create the opening between the Lateral Ventricles and 3rd Ventricle (Interventricular Foramen of Monro)
-connected to the Corpus Callosum by the Septum Pellucidum (inert tissue dividing lateral ventricles from each other)
Fornix
An enlarged subarachnoid space just underneath the Cerebellum.
Cisternae Magna
Connects the lower brainstem to the Cerebellum
-Has an opening called the Foramen Magendie (aperture that connects 4th ventricle to Subarachnoid space)
Inferior Medullary Velum
Responsible for CSF Absorption back into circulation.
-Has a puff (thin walled extension of arachnoid mater) sticking out and projecting into the Sup. Sagittal Sinus (Venous system).
-project through the dura mater into the Sup. Sagittal Sinus to drain CSF.
-ionic flex and hydrostatic pressure push and carry CSF from subarachnoid space into the Sup. Sagittal Sinus and recycle it in circulation.
Arachnoid Villa (Granulations)
Most CSF is absorbed where?
Superior Sagittal Sinus
Sometimes, with aging, Arachnoid Villi can become calcified, affecting their ability to absorb CSF.
-Senile Hydrocephalus (backup of fluid into Subarachnoid space that compresses brain - gait issues, dementia, etc)
-Can get a shunt placed to relieve pressure
Pacchionian Bodies
Produce around 500-1200 mL of CSF a day
Choroid Plexus
Need equilibrium of CSF production and absorption to avoid ____.
Hydrocephalus
Normal CSF Pressure:
8-15 mmHg lying down
16-24 mmHg standing up
-Affected by position changes
Normal CSF
