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Protection & Supply Apparatusesfor Central Nervous System
Meninges of Brain and Spinal CordCerebral Spinal Fluid (CSF) Circulation Blood Vessels of Brain and Spinal Cord
Guo Ling , MD, PhD
Department of Anatomy
Meninges of Brain and Spinal Cord
Concept : they are the connective tissue membranes covering the brain and the spinal cord (three layers)Meninges of brain & spinal
cord(out inward)
Spinal meninges
dura materarachnoidpia mater
cerebral dura mater
arachnoidcerebral pia
mater
spinal duramater
arachnoidspinal pia mater
Cerebral meninges
Cerebral pia mater
Arachnoid
Cerebral dura mater
Spinal pia mater
Spinal dura
arachnoid
Spaces Formed by Meninges & Relative Contents
1.Epidural Space Location: lying between spinal dura and internal periosteum of the vertebral canal. Contents: roots of spinal nerve,venous plexuses,rich fat Feature: minus atmospheric pressure.
2.Subarachnoid Space
Location: lying between arachnoid
and pia mater.
Contents: cerebrospinal fluid (CSF)
Features: plus pressure equal to the
normal atmospheric pressure Locally enlarged spaces(5):
terminal cistern(L2—S4)
cerebellomedullary cistern
interpeduncular cistern
pontine cistern
superior cistern
Grains:
arachnoid granulations
5 positions
Specific Structures Formed by Cerebral Dura Mater 1.Inclusion: cerebral falx cerebellar falx cerebellar tentorium dural sinuses 2.Communications among the sinuses:
Sup.sagittal sinus
Inf.sagittal sinus→straight sinus→confluence of sinuses→transverse sinus→sigmoid sinus→inter jug v
Cavernous sinus → sup.petrosal sinus
inf.petrosal sinus
2.Communications among the sinuses:
3.Cavernous Sinus(1) Position: lying on each side of sella turcica
(2) Contents: internal carotid artery & abducent nerve run through it ; and oculomotor,trochlear,
ophthalmic(V1) & maxillary(V2) nerves pass through its lateral wall into the orbit.
(3) Communication: facial v –-superior & inferior ophthalmic veins—--cavernous sinus
(4) Clinical significances: bacterial or viral infection in the dangerous facial trigone may spread to
the sinus via the above pathway causing sepsis & thrombosis in it and even negtively affecting
the ajacent crainal nerves,in which relative symptoms & signs will appear.
Cerebrospinal Fluid(CSF) 1.Producing Position CSF is secreted by the choroid plexuses in all ventricles. 2. Circulation R&L lateral ventricles
↓interventricular
↓foramina third ventricle
↓ cerebral aqueduct fourth ventricle
↓ R/L lateral foramina
↓ median foramen subarchnoid space
↓ arachnoid granulations superior sagittal sinus
↓ internal jugular vein
3.Clinical Significances If the pathways of CSF circulation are blocked, CSF will not be able to return to the epidural sinuses, and will stagnate in
cerebral ventricular system, leading to the swellen brain (hydrocephalus) especially in infants or children and to a high intrcranial pressure in adults in which the disfunctions
of brain or cerebral hernias may appear,resulting to sudden death. .
Arteries of CNS
I. Brain Arteries 1.Origin two sets of arteries
internal carotid artery
vertebral artery
Blood Vessels in CNS
The above branches of the artery collectively provide blood for the anterior 2/3 part of cerebral hemisphere including eyes, & anterior portion of thalamus.
(1) anterior cerebral a
(3) anterior choroidal a
(4) optic a
(5) posterior communicating a
(2) middle cerebral a
2. Branches of Internal Carotid Artery
(1)Anterior cerebral a supplies the medial surface of
cerebrum & upper part of dorsal surface of the cerebrum.
(2)Middle cerebral a supplies most part of the dorsolateral surface of cerebral hemisphere.
(3) anterior
choroidal a
(4) optic a
(5) posterior
communicating a
The three branches supply the areas with the same arterial names.
3. Cerebral Arterial Circle(Willis`s) 1) Composition(5 parts, 9 branches ): anterior communicating A , bilateral anterior cerebral As, bilateral internal carotid As , bilateral posterior communicating As, bilateral posterior cerebral As.
2) Location:
The circle lies on
inferior surface of
cerebrum & encircles
optic chiasma,
tuber cinereum &
mammillary bodies.
3)Functions :
The circle regulates
blood flow of both
cerebral hemispheres.
4.Two Kinds of Arterial Branches Anterior ,middle and posterior cerebral arteries and the cerebral arterial circle all possesses the following:
cortical branches central branches (IC,BN)
Few anastomoses exist among separate branches . If a branch is blocked or broken, the target area suffers a deadly attact,either stroke or bleeding, resulting in losses of sensation & paralyses.
5. Clinical Significances 1. The branches of cerebral arteries hardly establish anastomoses (so-called terminal As ). When one of them is blocked, the supplied regions of brain will completely lack blood supply, leading to neuronal necroses & apoptoses . 2. The arteries of brain seldom beat, which may link to their thin walls & their curved routes, bringing about no palpable pulses from the arteries. 3. The branches for internal capsule are easily broken and this may result in a worse bleeding, because they directly arise from middle cerebral A at a right angle and and their walls have to put up with the powerful rush force and high blood pressure from torrent blood flow.
II.Arteries of Spinal Cord
1.Four Origins Vertebral A Ascending cervical A Intercostal A Lumbar A
2. Branches of Vertebral Artery & Basilar Artery
(1)anterior spinal artery (1) (2) posterior spinal arteries (1)
(3) posterior inferior cerebellar arteries (2) (4) anterior inferior cerebellar arteries (2)
(5) labyrinthine arteries (2) (7) pontine arteries (3 or 4 pairs ) (8) superior cerebellar arteries (2)
(9) posterior cerebral arteries (2)
The above branches collectively provide blood for the posterior 1/3 portion of cerebral hemisphere and posterior part of thalamus as well as the cerebellum, brain stem & spinal cord.
Artery (1) ~ artery (5) are the branches of vertebral artery
Artery (7)~ Artery (9) are the branches of basilar artery
Vertebral A
Ant.spinal A
labyrinthine A
posterior cerebral A.
pontine A
superior cerebellar A
Ant.inf cerebellar A
Post.inf.cerebellar A
Post.cerebral A
3.It supplies most parts of occipital and temporal lobes.
Vertebral AAnt.spinal A
Basillar A
Post. Spinal A
Post. Intercostal A
Lumbar A
Ascending cervical A
4.Arterial Distribution Patterns in Spinal Cord
Ant. Spinal A
Post spinal A
Coronary A of spinal cord
III.Veins of Brain 1. Features (1) They own no relatively accompanying arteries. (2) There are two sets----superficial and deep veins. 2.Division (1) Superficial Vein ( 3 branches : sup, mid & inf ) They lie on the surface of the cerebrum and drains the blood from the cerebral cortex to venous sinuses : a. superior cerebral v (on the surface above LS ) →superior sagittal sinus b. middle cerebral v (situated in lateral sulcus--LS ) →cavernous sinus c. inferior cerebral v (on the surface under LS ) →cavernous sinus & transverse sinus
Superior cerebral V
Middle cerebral V
Inferior cerebral V
Sup.sagittal sinus
Transverse sinus
Sigmoid sinus
(2)Deep veins drain the blood from the deep medullar matter to venous sinuses:a.Internal cerebral V b.Great cerebral V straight sinus (lying in postoinferiorpart of corpus callosum) c.Basilar V.
Great cerebral vein is also called Galen`s vein.