Neuroanatomy 2: Meninges, Ventricular system, Brain Blood Supply Flashcards
CNS is surrounded and protected by three membranes of connective tissue:
Meninges
Dura Mater
(Arachnoid Mater)
Pia Mater
Dura Mater:
-thick layer of dense connective tissue
(attaches to the inner surface of the neurocranium)
Epidural space:
Separates the dura mater from the vertebral canal.
Dura mater surrounding the spinal cord ends at what level vertebrae?
S2
The dura mater has two layers:
Periosteal layer: attached to inner surface of the cranial cavities
Meningeal Layer: separates from the periosteal layer in several locations to form two distinct structures.( Dural reflections & Dural sinuses)
Dural reflections:
-forms incomplete partitions to divide the cranial cavity into compartments.
a. Falx Cerebri
b. Tentorium cerebelli
c. Falx cerebelli
Dural sinuses:
drains the venous blood of the brain into the circulatory system.
located between the two layers of the cranial dura mater.
a. Cavernous sinuses
b. superior and inferior sagittal sinuses
c. straight sinus
d. transverse sinuses
e. sigmoid sinuses
Falx cerebri:
sagittal sickle shape reflection of the dura mater that occupies the longitudinal fissure of the cerebrum & partially separates the hemispheres.
Tentorium cerebelli:
tent-like horizontal sheet that intervenes between the cerebellum & occipital lobe of the cerebral hemispheres. (notched anteriorly to provide passage for the midbrain)
Falx cerebelli:
less prominent vertical reflection of the dura in the sagittal plane along the vermis that partially separates the cerebellar hemispheres.
Cavernous sinuses:
Paired: Located in the middle of the cranial fossa on either side of the hypophyseal fossa of the sphenoid bone: drains the face of blood
Superior and inferior sagittal sinuses:
unpaired sinuses contained within the superior and inferior margins of the falx cerebri.
Straight sinus:
unpaired; receives the posterior end of the inferior sagittal sinus and meets with the superior sagittal sinus at the “confluence of sinuses”
Transverse sinuses:
paired sinus: in the posterior tentorium cerebelli
where the “confluence of sinuses” drains into.
Sigmoid sinuses:
located in the groove on the interior surface of the mastoid process(temporal bone).
Empties into the internal jugular vein.
(Clots are normally formed here because of it’s “S” shape)
What order does the blood drain from the brain in?
Inferior sagittal sinus travels into straight sinus and meets superior sagittal sinus at the confluence of sinuses.=>
transverse sinuses=> sigmoid sinuses=> internal jugular vein=> superior vena cava
(Cavernous sinus drains the face)
Arachnoid granulations:
small finger like projections: drains CSF into the dural sinuses.
(extend through dura mater into venous sinuses)
Allows CSF to move from subarachnoid space into venous circulation.
CSF uses arachnoid granulations to drain with the superior sagittal sinus.
Pia mater:
delicate, thin layer of connective tissue that is in touch with the surface of the brain & spinal cord
Denticulate ligaments:
lateral triangular extensions of the pia mater that anchor the spinal cord to the deep surface of the arachnoid and dura mater.
Filum terminale:
extension of the pia mater arising from the conus medullaris that extends inferiorly and fuses with the arachnoid and dura mater to anchor the spinal cord to the coccyx.
Meninges of the spinal cord from superficial to deep:
Vertebral column
Space 1: Epidural space (filled with fat for additional protection)
Layer 1: Dura mater
Meningeal layer (thicker than other meninges)
Layer 2: Arachnoid Mater (“web-like” appearance)
Space 2: Subarachnoid space (CSF found here)
Layer 3: Pia mater- tightly adhered to neural tissue itself
Dura mater of the spinal cord:
Sac that covers the spinal cord with bony attachments (foramen magnum, C1-C2, & S1 “dural sleeve”)
Epidural space surrounds this layer.
Arachnoid:
middle layer of avascular CT w/ collagen & elastic fibers.
Deep to the arachnoid layer is the subarachnoid space containing CSF.
Pia mater of spinal cord:
Denticulate ligaments: thickenings of the pia mater that suspend the spinal cord in the middle of it’s dural sheath.
Located between ventral & dorsal nerve roots
Protect the spinal cord against shock and sudden displacement/trauma
Conus medullaris:
The end of the spinal cord
L1/2 in adults
L4 in children
Cauda Equina:
The remaining spinal nerves
“horse-tail”
Dural sac/sleeve:
Dura mater surrounding cauda equina ending at S2
Filum terminale:
Tethers spinal cords to coccyx (extension of the pia mater)
Lumbar cistern:
-Filled with CSF
-Enlargement of subarachnoid space between conus medullaris(L2) & end of dural sac (S2)
-Site for lumbar puncture
The cerebral ventricle system is composed of:
2 lateral ventricles: Found in the four lobes of the brain
Third ventricle: found between the thalamic nuclei
Cerebral aqueduct: Runs through the midbrain
Fourth ventricle: found between the pons and cerebellum
(communicating network of cavities deep within the tissue of the brain)
CSF circulation:
Choroid plexus:
specialized arterial plexuses located within the ventricular spaces with functions to produce cerebrospinal fluid from arterial blood
-Serves as nutrient delivery and waste removal system for the brain tissue
-Subarachnoid space to provide fluid cushion around brain & spinal cord
-Unidirectional flow of CSF
-Absorbed by the venous system after it has performed it’s role within the CNS
Cortical vascular territories:
Vertebro-basilar system:
a) Vertebral arteries
b) Basilar A.
c) Posterior Cerebral A. (PCA) (occipital lobe-cortical blindness)
d) Posterior communicating arteries
e) Posterior anterior inferior cerebellar artery (PICA/also covers brain stem): most likely to cause stroke when damaged
f) Superior cerebellar (covers brain stem)
Carotid stystem:
a) middle cerebral a.
b) anterior cerebral a.
c) Anterior communicating a.
Circle of willis is made up of?
Anterior communicating artery
anterior cerebral artery
internal carotid artery
Posterior communicating artery
Posterior cerebral
What is the reason for the circle of willis?
If there is a blockage on one side, the blood is still able to go around the circle to still supply the brain w/ blood.
Arteries of the spinal cord:
