Anatomy of brain sulcus and gyrus - Dr.Sajith MD RD

1. Brain Anatomy S ulci & G yri By Dr.Sajith

2. Sulcus : A sulcus is depression or fissure in the surface of the brain. ( valleys ) Gyrus : A  gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more  sulci ( hills )

3. Typical continous fissure Interhemispheric fissure Sylvian fissure ( lateral sulcus ) Parieto -occipital fissure Collateral sulcus Central sulcus Calcarine Sulcus

4. Interhemispheric fissure Deep sulcus upto corpus collosum Divides brain into two hemisphere

5. Sylvian fissure deep , mostly horizontal insula is buried within it separates temporal lobe from parietal and frontal lobes

6. Parieto - occipital fissure very deep often Y-shaped from sagittal view X-shaped in horizontal and coronal views

7. Collateral sulcus Divides lingual and parahippocampal gyri from fusiform gyrus .

8. Central sulcus usually freestanding (no intersections) Seperates frontal and parietal lobe.

9. Calcarine sulcus

10. Lobes of brain Frontal lobe. Parietal lobe. Temporal lobe. Occipital lobe . Limbic lobe . Insular lobe.

11. • Frontal lobe : Anterior region of hemisphere; anterior to central sulcus , superior to sylvian fissure • Parietal lobe : Posterior region of hemisphere; posterior to central sulcus , anterior to parietooccipital sulcus • Occipital lobe : Posterior to parietooccipital sulcus • Temporal lobe : Inferior to sylvian fissure, anterior to angular gyrus

12. Lateral surface of brain

13. Medial surface of brain

14. Basal surface of brain

15. frontal lobe The frontal lobe constitutes the entire region in front of the central sulcus . Immediately in front of the central sulcus lies the precentral gyrus , which is the primary motor region of the cerebral cortex. In front of the precentral gyrus , the rest of the frontal lobe is divided into   superior ,  middle   and inferior frontal gyri .

16. Frontal lobe S ulci : Superior frontal sulcus . Inferior frontal sulcus . Precentral sulcus . G yri : Superior frontal gyrus . Middle frontal gyrus . Inferior frontal gyrus . Precentral gyrus

17. Frontal lobe gyrus Lateral Surface Precentral Gyrus --- primary motor area Superior Frontal Gyrus Middle Frontal Gyrus Inferior Frontal Gyrus Pars Opercularis Pars Triangularis Pars Orbitalis Medial Surface Medial Frontal Gyrus Paracentral Lobule Basal Surface Rectus Gyrus Orbital Gyrus ( superior, medial ,lateral ,inferior )

18. Parietal lobe Behind the central sulcus , and above the lateral fissure, lies the parietal lobe. Its most anterior part is the  postcentral gyrus , which is the site of the primary somatosensory cortex. Behind the postcentral gyrus , on the lateral surface of the hemisphere, the   intraparietal sulcus  divides the rest of the parietal lobe into superior and inferior parietal lobules.

19. Parietal lobe Sulci : Post-central sulcus . Intraparietal sulcus . Gyri : Post-central gyrus . Superior parietal gyrus . Inferior parietal gyrus .

20. Parietal lobe gyrus Lateral Surface Postcentral Gyrus ---- primary somatic area Superior Parietal Lobule Inferior Parietal Lobule ---- Wernicke’s area Supramarginal Gyrus Angular Gyrus Medial Surface Paracentral Lobule Precuneus

21. Temporal lobe The temporal lobe lies beneath the lateral fissure. On its lateral surface the temporal lobe is divided into three principal gyri that run roughly parallel to the lateral fissure: the  superior ,  middle  and  inferior temporal gyri . The superior temporal gyrus includes the primary auditory cortex.

22. Temporal lobe S ulci : Superior temporal sulcus (parallel sulcus ). Inferior temporal sulcus . G yri : Superior temporal gyrus . Middle temporal gyrus . Inferior temporal gyrus .

23. Temporal lobe gyrus Lateral Surface Superior Temporal Gyrus Middle Temporal Gyrus Inferior Temporal Gyrus Basal Surface Occipitotemporal Gyrus Medial Occipitotemporal Gyrus Lateral Occipitotemporal Gyrus

24. Occipital lobe The boundary between the parietal lobe and occipital lobe is not coincident with a single sulcus on the lateral surface of the hemisphere; however, it is clearly marked by the deep  parieto -occipital sulcus  on the medial surface. The occipital lobe does not bear any important landmarks on its lateral surface but on the medial surface, the prominent  calcarine sulcus  indicates the location of the primary visual cortex.

25. Occipital lobe Sulci : Superior occipital sulcus (extension of intraparietal sulcus ). Inferior occipital sulcus (extension of inferior temporal sulcus ). Gyri : Superior occipital gyrus . Middle occipital gyrus . Inferior occipital gyrus

26. Occipital lobe gyrus Lateral Surface Lateral Occipital Gyrus Superior Occipital Gyrus Inferior Occipital Gyrus Medial Surface Cuneus Lingual Gyrus Basal Surface Lateral occipito -temporal gyrus ( fusiform gyrus ). Medial occipito -temporal gyrus (lingual gyrus ).

27. Limbic lobe On the medial surface of the hemisphere, certain portions of the frontal, parietal and temporal lobes also constitute components of the limbic system. Curving around the corpus callosum , and running parallel to it, lies the  cingulate gyrus  , separated from the rest of the hemisphere by the  cingulate sulcus . The cingulate gyrus passes posteriorly and inferiorly round the posterior portion of the corpus callosum to become continuous with the  parahippocampal gyrus  of the temporal lobe. Deep to the parahippocampal gyrus , within the temporal lobe lies the  hippocampus. The cingulate gyrus , parahippocampal gyrus and hippocampus are referred to as the  limbic lobe .

28. Limbic lobe gyrus Outer Ring Cingulate Gyrus Isthmus of Cingulate Gyrus Parahippocampal Gyrus Uncus , Uncinate Gyrus Inner Ring Hippocampal Formation Hippocampus, Ammon's Horn Dentate Gyrus Fasciolar Gyrus Supracallosal Gyrus Subcallosal Area ( Parolfactory Area)

29. Insular lobe Lies deep in floor of sylvian fissure, overlapped by frontal, temporal and parietal. The  insular lobe  is thought to be involved in sensory and motor visceral functions as well as taste perception.

30. Insular lobe Sulci : Central sulcus . Short insular sulcus . Precentral sulcus . Gyri : Anterior insular lobule. Posterior insular lobule.

31. Insular lobe Anterior insular lobule (short insular gyri ): Anterior short insular gyrus . Middle short insular gyrus . Posterior short insular gyrus . Posterior insular lobule (long insular gyri ): Anterior long insular gyrus . Posterior long insular gyrus .

32. Sulcus and gyrus Sagittal Axial Coronal

33. Signs to identify sulcus in mri The midline sulcus sign : The longest sulcus running horizontally and entering the interhemispheric fissure is the central sulcus . The M sign : The typical upper case M shape of the inferior frontal gyrus is formed by its parts ( orbitalis , triangularis , and opercularis ).

34. signs The bifid post cg sign : Toward the interhemispheric fissure, the postcentral gyrus is medially fissured, enclosing the pars marginalis of the cingulated sulcus with both legs and thereby forming the characteristic bifid post cg sign . The thin post cg sign : On the surface, the precentral gyrus has a thicker anteroposterior diameter compared with the postcentral gyrus , which is thinner.

35. signs The handknob : defined the " handknob " as 1 single - shaped dorsally convex bulge of the precentral gyrus . The upper T sign : The intersection of the well-identifiable superior frontal sulcus with the precentral sulcus has the shape of an upper case T . The pre cg can be found immediately posterior to this T shape.

36. signs The L sign : The sfg terminates in the pre cg, which runs laterally from the posterior end of the sfg , therefore together forming an upper case L . The lower T sign : The inferior frontal sulcus posteriorly terminates in the pre sc, also in the shape of an upper case T that is dorsally bordered by the pre cg.

37. signs Inverted omega sign : the central sulcus more likely to have the shape of inverted omega. The bracket sign : The bihemispheric symmetric pars marginalis of the cingulate sulcus forms an anteriorly opened bracket.

38. Sagittal

39. NP/MGH Subcallosal gyrus Gyrus rectus Parietooccipital sulcus Fastigium, fourth ventricle Cingulate gyrus Calcarine sulcus Marginal ramus of Cingulate sulcus Superior parietal lobule Paracentral lobule Cingulate sulcus Superior frontal gyrus Cuneus Lingual gyrus

40. NP/MGH Gyrus rectus Parietooccipital sulcus Cingulate gyrus Calcarine sulcus Lingual gyrus Marginal ramus of Cingulate sulcus Superior parietal lobule Cingulate sulcus Caudothallamic groove Precuneus Central sulcus Cuneus Precentral gyrus Frontomarginal gyrus Superior frontal gyrus

41. NP/MGH Parietooccipital sulcus Calcarine sulcus Superior parietal lobule Marginal ramus of Cingulate sulcus Central sulcus Precentral sulcus Precuneus Corona radiata Superior frontal gyrus Lingual gyrus Inferior occipital gyrus

42. NP/MGH Inferior temporal gyrus Temporal horn, lateral ventricle Central sulcus Posterior orbital gyrus Frontomarginal gyrus Medial orbital gyrus Frontopolar gyrus Parietooccipital sulcus Lingual gyrus Inferior occipital gyrus Superior occipital gyrus Middle occipital gyrus Superior parietal lobule

43. NP/MGH Central sulcus Inferior Temporal gyrus Middle Temporal gyrus Superior Temporal gyrus

44. NP/MGH Central sulcus Lingual gyrus Inferior occipital gyrus Superior parietal gyrus Middle occipital gyrus Superior occipital gyrus Inferior Temporal gyrus Middle Temporal gyrus Superior Temporal gyrus Posterior orbital gyrus Anterior orbital gyrus Frontomarginal gyrus Inferior frontal gyrus

45. NP/MGH Inferior Temporal gyrus Superior Temporal sulcus Superior Temporal gyrus Anterior occipital sulcus Superior frontal sulcus Precentral sulcus Central sulcus Postcentral sulcus Angular gyrus Lateral fissure, posterior segment Inferior frontal gyrus, pars orbitalis Middle Temporal gyrus Inferior occipital gyrus Middle occipital gyrus Inferior frontal gyrus, pars triangularis

46. axial

47. NP/MGH Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Fusiform gyrus

48. NP/MGH Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Parahippocampal gyrus Hippocampal gyrus

49. NP/MGH Temporo-occipital fissure Inferior occipital gyrus Lingual gyrus Gyrus descendens Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Amygdala Hippocampus

50. NP/MGH Gyrus rectus Olfactory sulcus Medial orbital gyrus Subcallosal gyrus Posterior orbital gyrus Temporo-occipital fissure Middle occipital gyrus Lingual gyrus Amygdala Hippocampus Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Gyrus descendens

51. NP/MGH Superior occipital gyrus Intra-occipital sulcus Middle occipital gyrus Cingulate gyrus Parieto-occipital fissure Calcarine sulcus Cuneus Middle temporal gyrus Superior temporal sulcus Superior temporal gyrus Insula Inferior frontal gyrus, pars orbitalis Superior frontal gyrus Middle frontal gyrus Inferior frontal gyrus, pars opercularis Lateral fissure Lateral fissure Inferior parietal gyrus

52. NP/MGH Middle occipital gyrus Superior temporal gyrus Intra-occipital sulcus Superior frontal gyrus Central sulcus Superior occipital gyrus Parieto-occipital sulcus Superior temporal sulcus Lateral fissure Inferior parietal gyrus Postcentral gyrus Lateral fissure Middle frontal gyrus Inferior frontal gyrus

53. NP/MGH Superior occipital gyrus Cuneus Intra-occipital sulcus Middle occipital gyrus Central sulcus Precentral sulcus Precentral gyrus Central sulcus

54. NP/MGH Postcentral sulcus Superior frontal sulcus Central sulcus Intraparietal sulcus Superior frontal gyrus Middle frontal gyrus Superior parietal gyrus Centrum semiovale Parietooccipital sulcus Precuneus Angular gyrus Central sulcus Inferior frontal gyrus Supramarginal gyrus Postcentral sulcus

55. NP/MGH Postcentral sulcus Central sulcus Superior frontal sulcus Pars marginalis Intraparietal sulcus Superior frontal gyrus Middle frontal gyrus Superior parietal gyrus Angular gyrus Supramarginal gyrus Intraparietal sulcus Central sulcus

56. coronal

57. NP/MGH Olfactory bulb Gyrus rectus Medial Orbital gyrus Inferior Frontal gyrus Superior Frontal gyrus Middle Frontal gyrus Interhemispheric Fissure Inferior Frontal gyrus

58. NP/MGH Forceps minor Olfactory Sulcus Lateral orbital gyrus Inferior Frontal gyrus Superior Frontal gyrus Superior Frontal sulcus Middle Frontal gyrus Medial Orbital gyrus Gyrus rectus Anterior Orbital gyrus Lateral orbital sulcus

59. NP/MGH Inferior Frontal gyrus pars opercularis Superior Frontal gyrus Middle Frontal gyrus Sylvian Fissure Posterior Orbital gyrus Inferior Temporal gyrus Cingulate gyrus Circular insular sulcus Olfactory Sulcus Superior Temporal gyrus Middle Temporal gyrus Inferior Frontal sulcus short insular gyrus Gyrus rectus Medial Orbital gyrus

60. NP/MGH Superior Frontal gyrus Superior Frontal sulcus Middle Frontal gyrus Superior Temporal Sulcus Sylvian Fissure Amygdala Precentral sulcus Anterior commissure Cingulate sulcus Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Precentral gyrus

61. NP/MGH Superior Frontal gyrus Middle Frontal gyrus Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Fusiform gyrus Hippocampus CA1, cornu ammonis Parahippocampal gyrus Central Sulcus

62. NP/MGH Paracentral lobule Superior Temporal gyrus Middle Temporal gyrus Inferior Temporal gyrus Central Sulcus Postcentral gyrus Cingulate gyrus Intraparietal sulcus Fusiform gyrus Collateral sulcus Parahippocampal gyrus Supramarginal gyrus Intraparietal sulcus

63. NP/MGH Superior Temporal gyrus Middle Temporal gyrus Inferior temporal gyrus Fusiform gyrus Central sulcus Paracentral lobule

64. NP/MGH Fusiform gyrus Lingual gyrus Calcarine sulcus Cingulate gyrus Inferior temporal gyrus Middle temporal gyrus Supramarginal gyrus Intraparietal sulcus Central sulcus Paracentral lobule Postcentral gyrus

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