Neuroanatomy Quiz 2
What arteries supply the pons?
"Pontine arteries" Basilar (lateral and medial pons) SCA and AICA (dorsolateral pons)
Branches off the vertebral arteries
*Anterior spinal artery* *Posterior spinal artery* *Posterior inferior cerebellar artery (PICA)*
3 layers of choroid plexus
- Cuboidal epithelial cells/*ependymal cells* (with tight junctions) - Capillary network (surrounded by epithelial cells) - Connective tissue of Pia mater
What is the larger of the 2 terminal branches of the ICA?
1. Middle cerebral artery-> LARGER 2. Anterior cerebral artery
Anterior cerebral artery branches
> *Pericallosal artery* —> supplies oxygenated blood to the medial surface of the cerebral hemispheres, callosal and pericallosal regions. > *Callosomarginal artery*-> supplies the frontal lobe, the paracentral area (lobule), & anterior parietal lobe
What do the branches off of the internal carotid artery supply?
> Anterior half of the brain, primarily via the *anterior cerbral artery* an *middle cerebral artery* > Branches: - *Opthalmic artery* —> passes into orbit through the optic canal whit optic nerve; supplies orbital contents as well as the skin on the forehead and the bridge of the nose - *Anterior choroidal artery* —> Last branch to originate from Internal Carotid Artery. Cisternal segment: Artery passes through crural cistern, supplies optic tract, posterior limb of internal capsule, branches to midbrain,and lateral geniculate nucleus. -*Anterior communicating artery* —> provides connection between the 2 internal carotid arteries (directly between 2 anterior cerebral arteries) - *Posterior communicating artery* —> arises from middle cerebral artery; provides an anastomoses with the vertebral artery system - *Anterior cerebral artery* —> passes superior to corpus callosum and supplies the frontal portion of the ipsilateral cerbral hemisphere; also supplies portion of hemisphere along midline - *Middle cerebral artery* —> courses up lateral surface of the brain and supplies a large portion of the temporal, parietals, and frontal lobes of the ipsilateral cerebral hemisphere
*Choroid Plexus*
> Modified ependymal cells that *produce CSF* > found mostly in the *lateral ventricles* (which is where most CSF is produce) and small bit of choroid plexus found in 3rd & 4th ventricles > *formed where the Pia mater comes into direct contact with the ependyma* > *capillaries of choroid plexus are specalized*
What are the *arachnoid granulations*? Function?
> Outpuchings of arachnoid mater containing cerebral veins into superior sagittal sinus (most in SSS) > Assist in draining (& recycling) CSF into venous system
*Vertebro-basilar system*
> Provides most of the circulation to the cervical spinal cord, medulla, pons, cerebellum, mesencephalon, and the posterior parts of the diencephalon an telencephalon
Which ventricles are associated with which parts of the brain?
> Telencephalon —> Lateral ventricle > Diencephalon —> 3rd ventricle > Midbrain —> Mesencephalic (cerebral) aqueduct > Pons —> 4th ventricle > Medulla —> 4th ventricle
Is the *cerbral aqueduct* visible? (Aqueduct of Sylvius)
> Yes, it is a canal that is located between the third ventricle and the fourth ventricle
*Cerebrospinal fluid* (function)
> acellular, modified filtrate of blood *providing cushion & nourishment to CNS tissue* > *Reduces apparent weight (buoyancy) of CNS tissue* > brain floats in CSF, reducing gravitational compression on the base of the brain - also limits torsion due to acceleration
*Interthalamic adhesion* (massa intermeda)
> flattened band of tissue that connects both parts of the thalamus at their medial surfaces
*4th ventricle*
> floor formed by medulla and pons > roof formed by cerebellum > located in the brainstem, posterior to the pons and medulla oblongata > The fourth ventricle is continuous with the cerebral aqueduct and the central canal of the spinal cord. > This ventricle also connects with the subarachnoid space, allowing for the flow of CSF
branches of basilar artery
> pontine arteries > labyrinthine (internal auditory) artery > *anterior inferior cerebellar artery (AICA)* > superior cerebellar artery
What structures make up the lateral walls of the 3rd ventricle?
> situated in the middle of the cerebral hemispheres, between the right and left lateral ventricles. > inferior to the fornix and corpus callosum Roof: tela chorioidea (part of choroid plexus) Floor: hypothalamus, subthalamus, mammilary bodies, infundibulum (pituitary stalk), and the tectum of the midbrain *Lateral walls: walls of the left and right thalamus; thalamus encloses 3rd ventricle* Anterior wall: anterior commissure (white matter nerve fibers), lamina terminalis, and optic chiasma Posterior wall: pineal gland and habenular commissures
Define stroke
A disruption of blood supply to a part of the brain which results in sudden loss of brain function > *Ischemic stroke:* Most common type of stroke in older people, occurs when the flow of blood to the brain is blocked by the narrowing or blockage of a carotid artery > *Hemorrhagic stroke:* occurs when a blood vessel in the brain leaks or ruptures; also known as a bleed > *Transient Ischemic Attack (TIA):* brief episode of loss of blood flow to the brain, usually caused by a partial occlusion that results in temporary neurologic deficit (impairment); often precedes a CVA
cavernous sinus
A sinus containing venous blood located on each side of the body of the sphenoid bone, near the base of the brain, behind the bridge of the nose > Located on each side of the *sella turcica* and the *body of the sphenoid bone*
*Corpus callosum*
A thick band of axons that connects the two cerebral hemispheres and acts as a communication link between them.
*Circumventricular Organs* (CVOs)
Areas LACKING a blood brain barrier > These areas may have a secretory role (ex. Release of hormones) or blood sampling role > Have 7 CVOs in brain: 1. Subfornical organ 2. Pineal gland 3. Subcommissural organ 4. Area postrema 5. Posterior pituitary (neurohypophysis) 6. Median eminence 7. Organum vasculosum
What are the blood supply and nerve supply to the dura?
Blood: *middle meningeal artery* (This is a branch of the maxillary artery) - If Middle meningeal artery is broken due to trauma, the potential space (*epidural space*) between the dura mater and the cranium can fill wiht blood, creation an *epidural hematoma* - Potential space between the dura mater and the arachnoid mater = *subdural space* which can fill with blood, abusing a *subdural hematoma* - Cerebral arteries pass through the *subarachnoid space* before givin off smaller branches that supply brain; if these rupture = *subarachnoid hematoma* Nerve: sensory innervation from the trigeminal nerve in the anterior and middle fossa and from branches of the olfactory, oculomotor, vagus, and hypoglossal cranial nerves.
What are the *arachnoid trabeculae*?
Collagenous extensions of the arachnoid mater that give the arachnoid mater its characteristic webbed appearance.
*Interventricular Foramen* (foramen of Monr)
Connection between lateral ventricles and third ventricle
What is the difference between the epidural space in the cranium and the epidural space in the spine?
In the cranium, the epidural space is a POTENTIAL space In the spinal cord, the epidural space is a REAL space
What is the course of venous blood flow from the cerebral veins?
Inferior sagittal sinus —> great cerebral vein (of Galen) —> straight sinus Straight sinus & superior sagittal sinus are first to meet at confluence of sinuses —> blood drains lateral through transverse sinus —> jugular foramen —> internal jugular vein (IJV) —> circulation
How does the basilar artery end?
It divides into the L/R *posterior cerebral artery*
dural reflections
Mengial layer of dura mater that involuted onto itself A. *Falx cerebri* (divides cerebrum into Right & Left sides; The largest duralreflection; found in the longitudinal cerebral fissure, which divides the two hemispheres of the cerebrum) B. *Tentorium cerebelli* (separates the occipital lobes of the cerebrum from the cerebellum) C. *Falx cerebelli* (infolding below the tentorium cerebelli. It helps to separate the cerebellar hemispheres)
contents of cavernous sinus
O TOM CA(t) O- occulomotor n (III) T- trochlear n. (IV) O- Ophthalmic n. (V1) M- Maxillary n. (V2) C- Carotid artery (internal) A- Abducens n. (VI) T- nothing
*denticulate ligaments*
Specializations of the pia mater that anchor the spinal cord to the dura mater and limit the movement of the cord.
petrosal sinuses
Superior petrosal ---> transverse (--> sigmoid/IJV) Inferior ---> IJV directly
*Vertebral arteries*
The 2 vertebral arteries join *at the base of the pons!!*to form the *basilar artery* which splits (near the optic chiasm) to form the L/R *posterior cerebral arteries*
jugular foramen
Where the jugular vein leaves the skull Foramen most medial to foramen magnum (large)
*Circle of Willis*
a circulatory anastomosis that supplies blood to the brain and surrounding structures Made up by *vertebra-basilar arterial system* and by *internal carotid arteries,* connected by vertebro-basilar branches
What is an arteriovenous malformation?
a congenital malformation where abnormal anastomoses (connections) between arteries and veins
*Blood brain barrier*
a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances. > Astrocytic "feet" create a more impenetrable barrier than normal capillaries Advantages: > Prevents pathogens from gaining access to brain > *CO2,O2, H2O, lipid solubles can all diffuse across BBB* but no medications, bacteria/debris... Disadvantage: > makes it extremely difficult to deliver any therapeautic or nutrtional material to the brain
subarachnoid space
a space in the meninges beneath the arachnoid membrane and above the pia mater that *contains the cerebrospinal fluid* > continuous with brain AND spinal cord, so creates space for CSF to flow
What is an aneurysm?
an excessive localized enlargement of an artery caused by a weakening of the artery wall.
dural venous sinuses
collect venous blood from the brain and direct it into the internal jugular veins of the neck A. *Superior sagittal sinus* (meningeal layer of Dura splits to form the Falx cerbri & periosteal layer follows the bony cavity, creating a triangular space that is filled with the SSS) B. *Inferior saggital sinus* (This sinus runs along the bottom of the falx cerebri to the straight sinus) C. *Transverse sinus* (meningeal layer of dura splits to form the tentorium cerebelli & periosteal layer follows the bone, with resulting space being filled by the transverse sinus) D. *Straight sinus* (This dural venous sinus is formed where the inferior sagittal sinus merges with the great cerebral vein. It follows the place where the tentorium cerebelli attaches to the falx cerebri and joins the confluence of sinuses) E. *Sigmoid sinus* (These sinuses run along an S-shaped course and pass through the jugular foramen, which is located at the base of the occipital and temporal bones. From there, they become the internal jugular veins)
Intercavernous sinuses
connect the left & right cavernous sinuses through the hypophyseal fossa; deep to diaphragma sellae, anterior and posterior to the hypophysis Drain blood into the superior & inferior petrosal sinuses
Spinal meninges
dura mater, arachnoid mater, pia mater Subarachnoid space — CSF flow
*3rd ventricle of brain*
found in the diencephalon and communicates with lateral ventricles via intraventricular foramen > Functions: - Protection of the Brain From Trauma - Pathway for the Circulation of Cerebrospinal Fluid - Transportation of Nutrients to and Waste from the Central Nervous System
Where is the *confluence of sinuses*?
internal occipital protuberance (at level of external occipital protuberence) It is where the superior saggital sinus, the straight sinus, and the right and left transverse sinuses join together
What are the perforating arteries?
numerous small branches that originate from the circle of Willis and the ACA, MCA, PCA and basilar arteries Perforating arteries of MCA = *lenticulostriate arteries* - supply structures located deep within the telencephalon and diencephalon
What is the course of the *posterior cerebral arteries*
terminal branches of the basilar artery and supply the occipital lobes and posteromedial temporal lobes.
Supratentorial compartment
the tentorium partitions the cranial cavity into two compartments, this one contains the cerebral hemispheres
Dura mater
thick, dense, outermost layer of the meninges surrounding and protecting the brain and spinal cord > "Tough mother" > Has a *periosteal layer* - directly adhered to th bone (skull), especially at the sutures > Has a *meningeal layer* - Forms *dural reflections*
Pia mater
thin, delicate layer of CT that is the inner membrane of the meninges which adheres to the surface of brain > Different from the dura mater and arachnoid mater because it Follows convolutions of sulci > "soft mother"
arachnoid mater
weblike middle layer of the three meninges > Fibers look "spider webby" due to *archnoid trabculae* that extend from surface of brain (Pia mater) to underside of dura
What is the *lumbar cistern?*
where the arachnoid membrane enlarges to form a space between the L1 and S2 vertebrate. This area is used for lumbar punctures (preferable *L4 and L5*) This is where CSF in the subarachnoid space can be accessed with minimal potential for injury (b/c no spinal cord here— only *cauda equina*/nerve roots there, so only risk hitting "rootlets," but even those move out of the way when a needle is inserted)