[OT 104] Lec. 7: Vascular and Ventricular Systems

Ventricles in the brain =

chambers

[VENTRICULAR SYSTEM] A _____ ______ of cavities are lined with _____ and filled with _____ _____

A communicating system of cavities that are lined with ependyma and filled with cerebrospinal fluid

[VENTRICULAR SYSTEM] Responsible for the ____, _____, and ____ of the CSF

protection, transport, and removal

[VS] Cerebrospinal Fluid _____ in the surfaces of the ____ and _____ in the _____ space

CSF fluid circulates in the surfaces of the brain and spinal cord in the subarachnoid space

[VS] CSF is produced by the

choroid plexus

[VS] CSF Functions

• shock absorption

• mechanical buoyancy

• nourishment/reserve

• metabolite removal

  • CNS Lymphatic system

• pineal secretion pathway

[VS] CSF color

clear and colorless

[VS] CSF normal values

• 150 ml in circulation in total at a time

• 400 - 500 ml produced and reabsorbed per day

[VS] CSF mean pressure

• 70 to 180 mm H2O

• periodic changes occur with heartbeat and respiration

[VS] CSF Spinal tap or lumbar puncture

a diagnostic procedure done to collect spinal fluid to check for brain infections and content

[VS] CSF Spinal tap or lumbar puncture is done at

L3 - L4 or L4 - L5

[VS] CSF Distribution

1. Choroid plexus (lateral ventricles)

2. Intervertebral Foramina (Foramen of Monroe) (connect choroid plexus and 3rd ventricle)

3. Third Ventricle

4. Cerebral Aqueduct of Sylvia (Sylvia = Skinny man connecting 3rd and 4th ventricles)

5. Fourth Ventricle

6. Foramen of Luschka (Lateral, 2 arrows) & Foramen of Magendie (Medial, 1 arrow)

7. Subarachnoid space of SC

8. Arachnoid villi

[VS] CSF Which part of the brain does the Lateral Ventricle supply?

Cerebral Cortex

• Anterior horn - frontal lobe

• Posterior horn - occipital lobe

• Inferior horn - temporal lobe

[VS] CSF Which part of the brain does the 3rd Ventricle supply?

diencephalon

[VS] CSF Which part of the brain does the 4th Ventricle supply?

brainstem and cerebellum

[VS] CSF absorption: CSF is absorbed by the ____ ____ and reabsorbed into the ____ _____ _____

CSF is absorbed by the arachnoid villi nd reabsorbed into the dural venous sinuses.

[VS] CSF absorption: Initiated when ____ ____ exceeds ___ ____ ____

Initiated when CSF pressure exceeds venus sinous pressure

[VS] Blood-Brain Barriers consists of

• Blood-CSF barrier

• Vascular-endothelial barrier

• Arachnoid barrier

[VS] Blood-Brain Barriers ____ the ____ system from the ____ _____ to prevent ___ or ____ substances from entering the brain

Blood-Brain isolates the nervous system from the blood supply to prevent poisonous or toxic substances from entering the brain

[VS] Circumventricular organs

structures centered around the ventricles of the brain lacking blood-brain barriers.

[VS] Blood-Brain Barriers permeable to

• water

• gas

• electrolytes and glucose

[VS] Blood-Brain Barriers impermeable to

• proteins

• large organic molecules

[VS] Blood-Brain Barriers more permeable in children than adults

• Bilirubin - brain damage in premature children

• Alcohol - cerebellar damage

[VS] Common causes of conditions

1. Infection

2. Obstruction or stenosis

3. Herniation (masses, edema, hematoma, brain abscess)

4. Overproduction of CSF

5. Under-absorption and over-absorption of CSF

[VS] Conditions: Hydrocephalus

abnormal buildup of CSF volume in the ventricles

[VS] Conditions: Hydrocephalus - 4 types

• Communicating

• Non-communicating

• Normal pressure hydrocephalus

• Hydrocephalus ex-vacuo

[VS] Conditions: Hydrocephalus - A. Communicating type

• (-) obstruction in the brain

• overproduction or underabsorption

[VS] Conditions: Hydrocephalus - B. Non-Communciating type/obstructive

• (+) obstruction (CSF is blocked before leaving the ventricles)

1. Cerebral aqueduct

2. Interventricular foramen

3. Foramen of Magendie (median) and Luschka (lateral)

• Aqueductal (Sylvian) stenosis is narrowed down = CSF is unable to flow to fourth ventricle

[VS] Conditions: Hydrocephalus - C. Normal Pressure

• often caused by tumor, head injury, hemorrhage, infection or inflammation

• no increase in ICP but with increase in CSF

• can occur from unknown reasons

[VS] Conditions: Hydrocephalus - D. Hydrocephalus Ex Vacuo

• often in degenerative conditions and brain damage caused by head injury or stroke

• affects YA/MA

• causes decrease in brain tissue

• ventricles enlarge as compensatory action

[VS] Conditions: Hydrocephalus - Management

Shunting and Surgery

[VS] Conditions: Hydrocephalus - Shunting

Goal: transfer fluid from ventricles into peritoneal cavity

• For communicating, NPH, and HEV types

[VS] Conditions: Hydrocephalus - Surgery

Goal: remove the obstruction

• For non-communicating type

[VS] Conditions: Papilledema

• swelling of the optic disc due to elevated intracranial pressure = optic nerve compression

[VS] Conditions: Papilledema leads to

blindness or optic atrophy

[VS] Brain receives__ % of total blood from the ___ and uses % of oxygen absorbed in the ____

Brain receives 18% of the total blood from the heart and 20% of oxygen absorbed in the lungs

[VS] Brain time progression during oxygen loss

• 30-180 secs of oxygen loss = loss of consciousness

• 60 seconds = brain cells start dying

• 3 minutes = neuron gets extensively damaged, lasting brain damage becomes more likely

• 5 minutes of oxygen loss = imminent deathart

[VS] Arterial System is a _____ network of ____ at the ___ of the brain that gives rise to all major _____ _____

Arterial System is a hexagonal network of arteries at the base of the brain that gives rise to all major cerebral arteries

[VS] Arterial System - Major cerebral arteries

• Anterior Cerebral Artery (ACA)

• Anterior Communicating Artery

• Internal Carotid Artery (ICA)

• Posterior Communicating Artery

• Posterior Cerebral Artery (PCA)

[VS] Arterial System - Brain has 4 principal arteries which are

2 internal carotid arteries (ICA) and 2 vertebral arteries

[VS] Arterial System - 2 internal carotid arteries (ICA)

• anterior circulation

• receives and supplies 80% of blood

• begin at the bifurcation of the common carotid artery

[VS] Arterial System - 2 vertebral arteries

• posterior circulation

• receive and supply the remaining 20% of blood (backburner siya)

• begin at the bifurcation of the subclavian arteries

[VS] Arterial System - Anterior Circulation Pathway

Common Carotid Artery - ICA - Ophthalmic Artery, Anterior Cerebral Artery, Middle Cerebral Artery, Middle Cerebral Artery, Posterior Communicating Artery, and Anterior Choroidal Artery

[VS] Arterial System - Posterior Circulation Pathway

Subclavian Artery - Vertebral Artery (VA) - PICA, AICA, SCA, PCA, Anterior Spinal Artery, and Pontine Artery

[VS] Arterial System - Anterior Circulation: ICA branches

• Ophthalmic A. = first branch

• Ant. cerebral A. = involved in asymptomatic stroke

• Middle cerebral A. = largest and terminal branch; most commonly occluded

• Posterior communicating A.

• Ant. choroidal A.

[VS] Arterial System - Ophthalmic A. supplies?

• eyes, other orbital structures

• frontal scalp area

• ethmoid and frontal sinuses

• dorsum of nose

[VS] Arterial System - Ant. Cerebral A. supplies?

• medial aspect of hemispheres

• anterior frontal lob

• basal ganglia

[VS] Arterial System - Middle Cerebral A. supplies?

• lateral aspect of hemisphere (except occipital lobe)

• basal ganglia

[VS] Arterial System - Anterior Choroidal A. supplies?

choroid plexus

[VS] Conditions - Cerebrovascular accident (CVA) or stroke

concepts to consider upon blood flow distribution

• hemisphere location of disruption

• functions of the areas supplied:

  • cerebrum = C/L affectations

  • cerebellum = I/L affectations

[VS] Conditions - ACA Lesion

• LE > UE affected

  • C/L hemiplegia

  • C/L hemianesthesia

• head or eye turning towads lesion

• grasp reflex

• paratonia (Gegenhalten Syndrome) = inability to relax muscles

• disconnection apraxia = jerk movement due to problems in motor planning and difficulty with new movement

• akinetic mutism (abulla) = muted movement

• personality changes

• urinary incontinence

• gait apraxia

[VS] Conditions - MCA Lesion

• UE > LE affected

  • C/L hemiplegia

  • C/L hemianesthesia

  • C/L homonymous hemianopsia

• head or eye turning towards lesions

• dysphagia = difficulty swallowing

• aprosody = monotonous speech

• neglect = sees one side but does not notice

• aphasia (if left hemisphere is affected)

• visual perceptual deficits if right hemisphere is affected

[VS] Arterial System - Posterior circulation

Vertebral artery levels:

• vertebral artery

• basilar artery

• PCA

[VS] Arterial System - Posterior circulation: Vertebral A. Branches

• posterior inferior cerebellar artery = largest branch

• anterior spinal artery

• anterior inferior cerebellar artery

[VS] Arterial System - Posterior circulation: Basilar A. Branches

• pontine arteries

• superior cerebellar artery

[VS] Arterial System - Posterior circulation: Posterior Cerebral A. Branch

posterior communicating artery

[VS] Arterial System - Vertebral A.: What does the PICA supply?

• posterior inferior quarter of cerebellum

• medulla oblongata

[VS] Arterial System - Vertebral A.: What does the AICA supply?

• anterior inferior quarter of cerebellum

• inferior pons

[VS] Arterial System - Vertebral A.: What do the Basilar and Pontine Arteries supply?

• thalamus

• midbrain

• pons

• medulla oblongata

[VS] Arterial System - Vertebral A.: What does the Superior Cerebellar Artery supply?

• superior half of the cerebellum

• superior pons

• midbrain

[VS] Arterial System - Vertebral A.: What does the Posterior Cerebral Artery supply?

• occipital lobe

• lower temporal lobe

• lateral and third ventricles

• thalamus

• midbrain

[VS] Arterial System - Other areas in the brain supplied

• MCA, ACA = corpus striatum and internal capsule

• PCA, Basilar A., Posterior Comm. A. = thalamus

• PCA, SCA, Basilar A. = pons

• Vertebral A., ASA, PSA, PICA, Basilar A. = medulla obolongata

• SCA, AICA, PICA = cerebellum

[VS] Arterial System - Spinal cord 2 primary sources

spinal arteries and radicular arteries

[VS] Arterial System - Spinal cord: Spinal arteries

• 1 anterior spinal a.

• 2 posterior spinal a.

[VS] Arterial System - Spinal cord: Radicular Arteries

• anterior radicular a.

• posterior radicular a.

[VS] Arterial System - Spinal cord: Anterior spinal a. (ASA)

• larger; supplies 2/3 of SC

• along anterior median fissure

[VS] Arterial System - Spinal cord: Posterior spinal A. (PSA)

• supply posterior 1/3 of SC

• close to nerve roots

[VS] Arterial System - Spinal cord: Radicular Arteries

• arise from segmental spinal a.

• enter the intervertebral foramina

• enter the white and gray matter

[VS] Arterial System - Spinal cord: Anterior Sulcal A.

branches from the coronal artery that supplies blood to the anterior gray horns and lateral columns

[VS] Arterial System - Spinal cord: Vasocorona

• hugs the spinal cord; irregular ring of arteries with vertical connections

• made up of segmental arteries that are connected to the ASA and PSA

[VS] Arterial System - Artery of Adam Kiewicz

• nutritional artery

• unilateral, only seen in left side

[VS] Arterial System - Artery of Adam Kiewicz arises from the ___ at the level to = major source of blood supply to the lower __ of the SC

arises from the aorta at the level of T8-L4 = major source of blood supply to the lower 2/3 of the SC

[VENOUS S.] Brain - Veins of the Brain

• have very thin walls

• have no muscular tissue and no valves

• emerge from brain and travel in subarachnoid space

• pierce other meningeal layers and drain into the cranial venous sinuses

[VENOUS S.] Cerebrum

• superficial veins

  • superior cerebral veins

[VENOUS S.] Cerebrum - Superior cerebral veins are __ to__ branches that pass ____ over the ___ surface of the _____ hemisphere and empty into the ____ ____ ____

Superior cerebral veins are 8-12 branches that pass upward over the lateral surface of the cerebral hemisphere and empty into the superior sagittal sinus

[VENOUS S.] Cerebrum - Superficial middle cerebral vein drains the ___ surface of the ____ hemisphere, travels within the ____ _____ and drains into the 3 veins/sinuses

Superficial middle cerebral vein drains the lateral surface of the cerebral hemisphere, travels within the sylvian fissure and drains into the 3 veins/sinuses

[VENOUS S.] Cerebrum - Superficial middle cerebral vein: 3 veins/sinuses where it drains

• superior anatomic vein Trolard = superior sagittal sinus

• inferior anastomic vein of Labbe = transverse sinus

• 3rd end of SMCV extends anteriorly and inferiorly = cavernous sinus (plexus of veins near the sella turcica)

[VENOUS S.] Cerebrum - Deep veins

• inferior sagittal sinus = great cerebral vein

• internal cerebral veins and basal veins of rosenthal form the great cerebral vein = straight sinus

[VENOUS S.] Cerebrum - Dual venous sinuses

• sinuses in the dura mater

• between the periosteal and meningeal layers

• *CSF is also drained into this via arachnoid villi

[VENOUS S.] Cerebrum - Confluence of Sinuses

• AKA torcular herophili or torcula

[VENOUS S.] Cerebrum - Confluence of Sinuses: Connecting point/intersection of

• superior sagittal sinus

• straight sinus

• 2 transverse sinuses

• occipital sinus

[VENOUS S.] Cerebrum - Confluence of Sinuses corresponds to the ___ ____ ___ of the ___ bone of the skull; draining straight to the __ ____ ____

Confluence of Sinuses corresponds to the internal occipital protuberance of the occipital bone of the skull; draining straight to the R transverse sinus

[VENOUS S.] Brainstem - Midbrain veins

drain into the great cerebral vein or basal vein

[VENOUS S.] Brainstem - Pontine veins

• one medial, 2 lateral

• drain into the basal vein, cerebellar veins, or neighboring sinuses

[VENOUS S.] Brainstem - Medulla Oblongata veins

• drain into the spinal veins, occipital sinus, or neighboring sinuses

[VENOUS S.] Cerebellum

drains mainly on adjacent sinuses or to the great cerebral vein

[VENOUS S.] Cerebellum - Superior Group

• drains to the straight sinus or great cerebral vein

• drains to the transverse and superior petrosal sinuses

[VENOUS S.] Cerebellum - Inferior Group

drains to straight or sigmoid sinuses

[VENOUS S.] SC

• irregular external plexus in the epidural space

• usually follows the arteries

• drain into the vertebral venous plexus or vena cava

[VENOUS S.] SC veins and plexus

• Anterior median spinal vein

• Anterolateral spinal vein

• Anterior radicular and spinal

  medullary veins

• Anterior internal plexus

• Anterior external plexus

• Posterior median spinal vein

• Posterior intermediate spinal vein

• Venous vasocorona

• Posterior radicular and spinal medullary veins

• Posterior internal plexus

• Posterior external plexus