Khaleel Alyahya, PhD, MEd King Saud University School of

Transcription

1 CEREBRAL BLOOD CIRCULATION Khaleel Alyahya, PhD, MEd King Saud University Schl f

2 OBJECTIVES At the end f the lecture, students shuld be able t: List the cerebral arteries. Describe the cerebral arterial supply regarding the rigin, distributin and branches. Describe the arterial Circle f Willis. Describe the cerebral venus drainage and its terminatin. Describe arterial & venus vascular disrders and their clinical manifestatins.

3 WATCH

4 Review: THE BRAIN Large mass f nervus tissue lcated in cranial cavity. Has fur majr regins. Cerebrum (Cerebral hemispheres) Diencephaln: Thalamus, Hypthalamus, Subthalamus & Epithalamus Cerebellum Brainstem: Midbrain, Pns & Medulla blngata

5 Review: CEREBRUM The largest part f the brain, and has tw hemispheres. The surface shws elevatins called gyri, separated by depressins called sulci. Each hemispheres divided int fur lbes by deeper grves. Lbs are separated by deep grves called fissures.

6 Review: BLOOD VESSELS Bld vessels are the part f the circulatry system that transprts bld thrughut the human bdy. There are three majr types f bld vessels: Arteries, which carry the bld away frm the heart. Capillaries, which enable the actual exchange f water and chemicals between the bld and the tissues. Veins, which carry bld frm the capillaries back tward the heart. The wrd vascular, meaning relating t the bld vessels, is derived frm the Latin vas, meaning vessel. Avascular refers t being withut (bld) vessels.

7 Review: HISTOLOGY The arteries and veins have three layers, but the middle layer is thicker in the arteries than it is in the veins: Tunica Intima (the thinnest layer): a single layer f simple squamus endthelial cells. Tunica Media (the thickest layer in arteries): is made up f smth muscle cells and elastic tissue. Tunica Adventitia (the thickest layer in veins) entirely made f cnnective tissue. Capillaries cnsist f little mre than a layer f endthelium and ccasinal cnnective tissue.

8 Review: BLOOD Bld is the actual carrier f the xygen and nutrients int arteries. Bld is made mstly f plasma, which is a yellwish liquid that is 90% water. Plasma cntains als salts, glucse and ther substances. Mst imprtant, plasma cntains prteins that carry imprtant nutrients t the bdy s cells and strengthen the bdy s immune system. Bld has main 3 types f bld cells that circulate with the plasma.

9 CEREBRAL CIRCULATION The mvement f bld thrugh the netwrk f bld vessels t supply the brain. The arteries carry xygenated bld and ther nutrients t the brain. The veins carry dexygenated bld back t the heart remving carbn dixide and ther metablic prducts. The mvement f bld in the cerebral circulatin is called cerebral bld flw.

10 CEREBRAL ARTERIAL SUPPLY The arterial cerebral circulatin is divided int anterir and psterir cerebral circulatins. The anterir and psterir cerebral circulatins are intercnnected via bilateral psterir cmmunicating arteries. Psterir cmmunicating arteries are part f Circle f Willis. Lcated n the base f the brain. It Encircles: Optic chiasma Hypthalamus Midbrain The cerebral arterial supply is prvided by tw systems: Cartid System Supply anterir prtin f the brain. Vertebr-Basilar System Supply psterir prtin f the brain.

11 CIRCULUS ARTERIOSUS (CIRCLE OF WILLIS) Named after Thmas Willis ( ), an English physician It is Frmed by: Tw Anterir cerebral arteries Tw Internal cartid arteries Tw Psterir cerebral arteries Tw Psterir cmmunicating arteries One Anterir cmmunicating artery It Gives numerus small vessels that penetrate the surface f the brain Perfrating arteries Anterir perfrating arteries Psterir perfrating arteries

12 ANTERIOR PERFORATING ARTERIES Arise frm: Anterir cerebral artery Anterir cmmunicating artery Middle cerebral artery Enter brain thrugh: Anterir perfrated substance irregularly quadrilateral area in frnt f the ptic tract and behind the lfactry trigne. Supply: Large part f basal ganglia Optic chiasma Internal capsule Hypthalamus

13 POSTERIOR PERFORATING ARTERIES Arise frm: Psterir cerebral artery Psterir cmmunicating artery Enter brain thrugh: Psterir Perfrated substance Supply: Ventral prtin f Midbrain Parts f Subthalamus and Hypthalamus

14 ANTERIOR CEREBRAL ARTERY Supplies: Orbital and medial surfaces f frntal and parietal lbes

15 MIDDLE CEREBRAL ARTERY Supplies: Entire Superlateral surface: Smatsensry Crtex Mtr Crtex Brca's Area linked t speech prductin Heschl s Gyrus t prcess incming auditry infrmatin Wernicke s Area It is invlved in the understanding f written and spken language

16 POSTERIOR CEREBRAL ARTERY Supplies: Anterir and inferir tempral lbes Uncus Lcated n the tip end f the medial surface f the parahippcampal gyrus. Part f the lfactry crtex that prcesses infrmatin frm the sense f smell. Inferir tempral gyri Inferir and Medial Occipital lbe

17 CEREBRAL ARTERIES

18 DISTRIBUTION OF CEREBRAL ARTERIES

19 BASILAR ARTERY Supplies: Midbrain and Cerebellum. Branches: Anterir inferir cerebellar artery Pntine branches Superir cerebellar artery

20 ARTERIAL DISORDER Strke Sudden cclusin Hemrrhage Aneurysm lcalized, bld-filled ballnlike bulge in the wall f a bld vessel. Angima is benign tumrs derived frm cells f the vascular r lymphatic vessel walls (epithelium) r derived frm cells f the tissues surrunding these vessels.

21 ACCLUSION OF ACA Manifestatins: Mtr disturbance in cntralateral distal leg Difficulty in Prefrntal lbe Functins: Cgnitive thinking Judgment Mtr initiatin Self mnitring

22 ACCLUSION OF MCA Manifestatins: Cntralateral weakness f: face, arm, and hand mre than legs Cntralateral sensry lss f: face, arm, and hand mre than legs visual field cut (damage t ptic radiatin) Aphasia: language disturbances Brca's: prductin Wernicke's: cmprehensin

23 ACCLUSION OF PCA Manifestatins: Visual disturbances Cntralateral hmnymus hemianpsia Bilateral lesins: crtical blindness patients unaware they cannt see (Antn's syndrme) Memry impairment If tempral lbe is affected

24 HOW WE ARE DOING..? Which statement(s) f the fllwing is NOT Wrng? Anterir cerebral arteries supply Brca's and Wernicke s Area..!! Occlusin f MCA causes difficulty in Prefrntal lbe s functins..!! Middle cerebral arteries are part f Willis Circle..!! Aneurysm is benign tumrs derived frm cells f the vascular r lymphatic vessel walls..!! Psterir cerebral arteries supply anterir and inferir tempral lbes..!!

25 CEREBRAL VENOUS DRAINAGE It invlves: Superficial (crtical) veins: Drain the crtical surface Deep veins: Drain the deep structures These veins ultimately drain int: Dural Venus Sinuses The Veins are thin walled and are devid f valves.

26 SUPERFICIAL CORTICAL VEINS Lie n the brain surface, in the Subarchnid space. They are divided int: Superir cerebral veins Inferir cerebral veins Superficial middle cerebral vein

27 SUPERFICIAL CORTICAL VEINS Superir Cerebral Veins 6 t 12 veins Drain lateral surface f brain abve the lateral sulcus Terminate mainly int the Superir Sagittal sinus, and partly int superficial middle cerebral vein.

28 SUPERFICIAL CORTICAL VEINS Inferir Cerebral Veins Run belw the lateral sulcus Drain the lateral surface f the tempral lbe Terminate partly int superficial middle cerebral vein & partly int Transverse sinus.

29 SUPERFICIAL CORTICAL VEINS Superficial Middle Cerebral Vein Runs alng the lateral sulcus Terminates int the Cavernus sinus Cnnected psterirly by Superir & Inferir anastmtic veins t Superir Sagittal & Transverse sinuses respectively.

30 DEEP CEREBRAL VEINS They drain the internal structures; Basal ganglia Internal capsule Thalamus They merge t frm the Internal Cerebral Veins. The tw veins unite in the midline t frm the Great Cerebral vein. This shrt vessel is cntinuus with the Straight Sinus.

31 DURAL VENOUS SINUSES Paired Single Transverse Sigmid Cavernus Petrsal Superir sagittal Inferir sagittal Straight Occipital Bld flws frm transverse & sigmid sinuses int IJV

32 WATCH

33 VENOUS DISORDER Infarctin refers t tissue death (necrsis) that is caused by a lcal lack f xygen due t bstructin f the tissue's bld supply Sinus thrmbsis: SSS thrmbsis Superir Sagittal Sinus Can cmplicates ear infectin Cavernus Sinus thrmbsis As a cmplicatin f infectin in the dangerus area f the face Obstructin f venus drainage f the brain leads t Cerebral swelling (edema) and raised Intracranial Pressure.

34 ALSO, HOW WE ARE DOING..? Which statement(s) f the fllwing is Wrng? 1. Superir Cerebral Veins terminate mainly int the Superir Sagittal sinus, and partly int superficial middle cerebral vein..!! 2. Infarctin refers t tissue death (necrsis)..!! 3. Superir Cerebral Veins drain lateral surface f brain abve the lateral sulcus..!! 4. Inferir Cerebral Veins terminate partly int superficial middle cerebral vein & partly int Transverse sinus..!! 5. Superficial Middle Cerebral Vein drains the lateral surface f the tempral lbe..!!

35 QUESTION?