LATERAL SURFACE OF CEREBRAL HEMISPHERE.pptx

Rhotons referrance.

1. LATERAL SURFACE OF CEREBRAL HEMISPHERE Dr B Vinod Mch Neurosurgery Resident Gandhi medical college Hyderabad

2. HEMISPHERIC SURFACES 3 Surfaces Lateral-faces cranial cap laterally Medial-frontal, parietal occipital faces falx cerebri temporal lobe faces lateral aspect of midbrain Basal-faces floor of anterior ,middle cranial fossae & tentorium

3. 3 Borders separate the three cerebral surfaces Superior border- follows SSS &upper edge of interhemispheric fissure(from frontal to occipital) which separates lateral and medial surfaces. Lateral border -has anterior and posterior parts. anterior part extends from the frontal pole along the lateral border of the basal surface of the frontal lobe to the sylvian fissure and separates the lateral and orbital surfaces of the frontal lobe. The posterior part of the lateral border has a gentle upward convexity that extends along and conforms with the lateral edge of the middle fossa floor and tentorium, and anteriorly turns upward

4. around the temporal pole to reach the sylvian fissure. It separates the lateral surface of the temporal and occipital lobes from the basal surface. Medial border: Has frontal to occipital parts

5. Central sulcus Separates anterior motor area (frontal) and sensory area posteriorly(parietal) Begins at superior border of lateral surface extending onto medial surface nearly 90% Intersects upper hemisphere border approx. 2cm behind midpoint between frontal and occipital poles Usually ends approx. 2-2.5cm behind the ascending ramus of sylvian fissure It extends laterally, inferiorly & anteriorly forming angle of 70 degree with superior border of hemisphere. Has two curves :- superior curve( convexity posterior)- well defined. Inferior curve (convexity anterior)

6. 98% separated from sylvian fissure by subcentral gyrus 2% joins together Terminates in paracentral lobule which represents foot(C/L)

7. Sylvian fissure Sylvian fissure and central sulcus most important landmark on lateral surface Sylvian fissure is most distinct & consistent landmark on lateral surface. It carries MCA & and its branches It provides surgical gateway connecting the cerebral surface to anterior part of basal surface & cranial base. Has superficial and deep part.

8. Superior part Has stem and 3 rami Stem: begins medially at anterior clinoid process extends laterally along sphenoid ridge between junction of frontal & temporal lobe to pterion Where stem divides into anterior horizontal ,anterior ascending & posterior rami Posterior rami: longest , Represents posterior communication of fissure, Directed posterior and upward separating frontal and parietal lobes above from temporal lobe below, Ends in inferior parietal lobule at SMG.

9. Deep part hidden a/k/a sylvian cistern Divided into sphenoidal & opercular

10. Sphenoidal compartment Laterally -from cistern around ICA between fronal & temporal lobe Roof –post part of orbital surface of frontal lobe & anterior perforated substance Caudate lobe Lentiform nucleus located above roof Anterior limb of internal capsule Floor: anterior part of planum polore Anterior segment of uncus at medial part of floor Amygdala

11. This compartment communicates medially through sylvian vallecula a tubular opening between frontal and temporal lip Where MCA passes and provides communication between sylvian fissure & cisterns around optic nerve an ICA

12. Operculo-insular compartment Formed by two narrow clefts Opercular & insular Opercular –located where sylvian fissure faces frontal lobe and parietal lobe above Faces sylvian surface of temporal lobe below

13. Frontal lobe Includes 1/3 rd of hemisphere surface. Boundaries Behind - central sulcus Above –hemispheric border Lower –anterior faces orbital roof Posterior part –sylvian border Has 3 sulci : Precentral Superior frontal Inferior frontal

14. 3 sulci divides into One vertical gyrus(PCG)- parallels central sulcus 3 horizontal gyrus: SFG MFG IFG Superior frontal gyrus: Between superior border of hemisphere and superior frontal sulcus Middle frontal gyrus : Between superior and inferior frontal sulci Situated lateral to cingulate gyrus on medial side Both separated by deep white matter forming centrum semiovale

15. Inferior frontal gyrus Between inferior frontal sulcus and sylvian fissure Divided anterior to posterior into Pars orbitalis Pars triangularis by anterior horizontal and anterior ascending rami Pars opercularis

16. 3 rami Marks anterior limit of insula Also marks the anterior limit of basal ganglia and frontal horn of LV

17. Parietal lobe Boundaries Superior-interhemispheric surface Anterior- central sulcus Posterior- upper end of parieto-occipital fissure to pre-occipital notch Infero-laterally-sylvian fissure Two sulci: Post central Intraparietal Which divides into Postcentral gyrus Superior parietal & Inferior parietal lobule

18. Post central sulcus Similar to central sulcus shape but frequently broken into several discontinuous parts by gyral bridges Intraparietal sulcus: Oriented anteri-posterior Parallel and 2-3 cm lateral to superior border of superior hemisphere Dept of sulci is directed to roof of atrium and occipital horn

19. Superiro parietal lobule : extend from superior of hemisphere to intraparietal sulci Inferior parietal lobule : Has anterior and posterior parts Anterior part : formed by supramarginal gyrus (Area 40) SMG located at atrium of LV Continous with lower end of post central sulcus Part below sylvian fissure is continuous with superior temporal gyrus

20. Posterior part : Formed by Angular gyrus (Area 39) Arches over upward end of superior temporal sulcus

21. Occipital lobe Occipital convexity is not clearly separated from temporal and parietal lobes by any clear sulci. Lobe has number of irregular convolations with considerable variability Most consistent sulci of this lobe is the lateral occipital sulcus, Short and horizontal, divides lobe into superior and inferior occipital gyri

22. Lateral sulcus descends on lateral surface , behind posterior part of parieto-occipital arcus, that caps parieto-occipital sulcus. Anterior to P-O sulcus is parietal lobe. Posterior is occipital lobe. Lambdoid suture joins sagittal suture at parieto-occipital junction.

23. Temporal lobe Located below sylvian fissure Has three parallel gryi divided by two sulci (superior &inferior) Superior temporal Middle temporal Inferior temporal Both gyri and sulci are parallel to sylvian fissure

24. Superior temporal gyrus . Located between sylvian fissure and superior temporal sulcus It extends backward ,obliquely and medially towards postero-superior angle of insula to form lower wall of posterior part of floor of sylvian fissure. Area of language &auditory Middle temporal gyrus . Between superior and inferior temporal sulci Structures located deep to MTG are, Temporal horn of LV, Ambient cistern, Crural cistern

25. Inferior temporal gyrus Located below inferior temporal sulci Continous around inferior border of hemisphere to form lateral part of basal surface. MTG & ITG –integrate vision with temporal lobe auditory function