Sulcal and gyral neuroanatomy

This presentation provides a comprehensive review of major sulci of brain which help in defining the different lobes of brain.Very useful for first year residents.

1. Sulcal and Gyral Anatomy of Brain

2. NeuroEmbryology

3. NeuroHistology The cerebral cortex is the outer layer of neural tissue. The cerebral cortex is gray matter, consisting mainly of cell bodies and capillaries. It contrasts with the underlying white matter, consisting mainly of the white myelinated sheaths of neuronal axons. The phylogenetically  most recent part of the cerebral cortex, the neocortex , is differentiated into 6 horizontal layers; the more ancient part of the cerebral cortex, the hippocampus , has at most three cellular layers. Neurons in various layers connect vertically to form small microcircuits, called cortical columns . Different neocortical regions known as Brodmann areas  are distinguished by variations in their histological structure. http://cercor.oxfordjournals.org/   "Patricia Goldman- Rakic : 1937-2003" .  Oxford University Press .

4. The different cortical layers contain a characteristic distribution of neuronal cell types and connections with other cortical and subcortical regions. There are direct connections between different cortical areas and indirect connections via the thalamus. Layer I, the molecular layer Layer II, the external granular layer Layer III, the external pyramidal layer Layer IV, the internal granular layer Layer V, the internal pyramidal layer Layer VI, the polymorphic or multiform layer Cortical neurons are generated within the ventricular zone . The glial fibers produced in the first divisions of the progenitor cells are radially oriented, spanning the thickness of the cortex from the ventricular zone to the outer pial surface, and provide scaffolding for the migration of neurons outwards from the ventricular zone.  http://cercor.oxfordjournals.org/   "Patricia Goldman- Rakic : 1937-2003" .  Oxford University Press . NeuroHistology Nissl -stained motor cortex  Nissl -stained visual cortex  Golgi-stained motor cortex 

5. The layered structure of the mature cerebral cortex is formed during development, in an inside-out order. The humans have cortical thicknesses of 2.3—2.8 mm . There is an approximately logarithmic relationship between brain weight and cortical thickness. The thickness of different cortical areas varies but in general, sensory cortex is thinner than motor cortex.  *positive association between the cortical thickness and intelligence .  * somatosensory cortex is thicker in migraine   sufferers, though it is not known if this is the result of or the cause of them.  * polymicrogyria where there are four layers instead of six, is in some instances seen to be related to dyslexia. http://cercor.oxfordjournals.org/   "Patricia Goldman- Rakic : 1937-2003" .  Oxford University Press . NeuroHistology

6. Defining the lobes central ( rolandic ) sulcus sylvian (lateral) sulcus frontal lobe temporal lobe occipital lobe parietal lobe

7. Development of Sulci Source: Ono, 1990 Sulci appear at predictable points in fetal development with the most prominent sulci (e.g., Sylvian fissure) appearing first.

8. Comparative Neuroanatomy Source: Comparative Mammalian Brain Collection The complexity of sulci increased throughout evolution http://brainmuseum.org/

9. Major Sulci Fissures are really deep sulci Typically continuous sulci Interhemispheric fissure Sylvian fissure Parieto -occipital fissure Collateral sulcus Central sulcus Calcarine Sulcus Typically discontinuous sulci Superior frontal sulcus Inferior frontal sulcus Precentral sulcus Postcentral sulcus Intraparietal sulcus Cingulate sulcus Superior temporal sulcus Inferior temporal sulcus Other minor sulci are much less reliable Source: Ono, 1990

10. Interhemispheric Fissure - divides brain into 2 hemispheres

11. deep , mostly horizontal separates temporal lobe from parietal and frontal lobes appears around the 14 th gestational week side branches - the ascending ramus and the horizontal ramus , subdivide the inferior frontal gyrus and also contains the transverse temporal gyri . due to a phenomenon called  Yakovlevian torque , the lateral sulcus is often longer and less curved on the left hemisphere than on the right. Sylvian Fissure Sylvian Fissure (or lateral sulcus )

12. Parieto -occipital Fissure often Y-shaped from sagittal view, X-shaped in horizontal and coronal views The  lateral part  of the fissure is situated about 5 cm in front of the occipital pole of the hemisphere, and measures about 1.25 cm in length. The  medial part  of the fissure runs downward and forward as a deep cleft on the medial surface of the hemisphere, and joins the calcarine fissure It marks the boundary between the  cuneus and precuneus , and also between the parietal and occipital lobes.

13. Calcarine Sulcus Calcarine sulcus (blue) located at the caudal  end of the medial  surface of the brain it is joined at an acute angle by the medial part of the parieto -occipital sulcus . contains primary visual cortex V1 Cuneus (pink) -visual areas on medial side above calcarine (lower visual field) Lingual gyrus (yellow) -visual areas on medial side below calcarine and above collateral sulcus (upper visual field)

14. Collateral Sulcus divides lingual (yellow) and parahippocampal (green) gyri from fusiform gyrus (pink ) it lies below and lateral to the  calcarine fissure, from which it is separated by the lingual grus ; in front, it is situated between the  phg and the anterior part of the fusiform gyrus .

15. Cingulate Sulcus divides cingulate gyrus (turquoise) from precuneus (purple) and paracentral lobule (gold ) The  cingulate sulcus  is on the medial wall of the cerebrum. The frontal and parietal lobes are separated from the cingulate gyrus  by the cingulate sulcus .

16. Intraparietal Sulcus anterior end usually intersects with inferior postcentral sulcus (or the ascending intraparietal sulcus ) posterior end usually forms a T-junction with the transverse occipital sulcus (just posterior to the parieto -occipital fissure) IPS divides the superior parietal lobule from the inferior parietal lobule (angular gyrus , gold, and supramarginal gyrus , lime) POF

17. Central, Postcentral and Precentral Sulci Central Sulcus (red) -usually freestanding (no intersections) -just anterior to ascending cingulate Postcentral Sulcus (blue) -often in two parts (superior and inferior) -often intersects with intraparietal sulcus -marks posterior end of postcentral gyrus ( somatosensory strip, purple) Precentral Sulcus (green) -often in two parts (superior and inferior) -intersects with superior frontal sulcus (T-junction) -marks anterior end of precentral gyrus (motor strip, yellow) ascending band of the cingulate

18. Identification of Central Sulcus The CS starts in or near the superomedial border and runs downwards and forwards for about 8 to 10 cm to end slightly above the posterior ramus of the lateral sulcus , from which it is always separated by an arched gyrus . It makes an angle of about 70 degrees with the median plane. It demarcates the primary motor and somatosensory areas of the cortex. Radiologically the CS is an important landmark. It separates the frontal from the parietal lobes and is a landmark to consider when localizing brain lesions. There are various shapes of the CS. The most common patterns have been described as “omega” shaped , or “lambda” shaped. These shapes are not so common and the pattern may vary so much that it is almost impossible to have any certainty in identifying the CS based purely on these patterns.

19. The CS is the only sulcus that divides the brain at its superior surface. Thus, it is the only sulcus that lies in the coronal plane that runs from the lateral part of the brain to the midline. The CS can be identified by examining axial slices. Looking at a normalized brain, the CS is the easiest to spot on an axial slice with a Z-coordinate (superior –inferior) around 60 mm above the AC-PC plane. Identification of Central Sulcus ascending band of the cingulate

20. 1. Superior frontal sulcus ( PreCS sign): The posterior end of the superior frontal sulcus joins the precentral sulcus in 85%. 2. Sigmoid “Hook”: Hook like configuration of the posterior surface of the precentral gyrus . The “hook” corresponds to the motor hand area and is well seen on CT (89%) and MRI (98%). 3. Pars bracket sign: The paired pars marginalis form a “bracket” to each side of the IH fissure at or behind the CS (96%). 4. Bifid post-CS sign: The post-CS is bifid (85%). The bifid post-CS encloses the lateral end of the pars marginalis (88%). 5. Thin post-CG sign: The postcentral gyrus is thinner than the precentral gyrus (98%) 6 . Intraparietal sulcus (IPS): In axial MRI, the IPS intersects the post-CS (99%). 7. Midline sulcus sign: The most prominent convexity sulcus that reaches the midline interhemispheric fissure is the CS (70%). Identification of Central Sulcus

21. NP/MGH Superior frontal sulcus - preCS sign the posterior end of the superior frontal sulcus joins the precentral sulcus in 85% The Central Sulcus (CS) Precentral sulcus Superior frontal sulcus Precentral gyrus Central sulcus Superior frontal gyrus Superior frontal sulcus Precentral sulcus Precentral gyrus

22. NP/MGH Sigmoid “Hook” hooklike configuration of the posterior surface of the precentral gyrus the “hook” corresponds to the motor hand area. The “hook” is well seen on CT (89%) and MRI (98%). The Central Sulcus (CS) Precentral sulcus Central sulcus

23. NP/MGH pars bracket sign The paired pars marginalis form a “bracket” to each side of the interhemispheric fissure at or behind the central sulcus (96%). The Central Sulcus (CS) Precentral sulcus Superior frontal sulcus Precentral gyrus Central sulcus Pars bracket Paracentral lobule

24. NP/MGH pars bracket sign The Central Sulcus (CS) Precentral sulcus Superior frontal sulcus Precentral gyrus Central sulcus Pars bracket Pars bracket

25. NP/MGH Bifid post-CS sign the post-CS is bifid (85%). The bifid post-CS encloses the lateral end of the pars marginalis (88%). The Central Sulcus (CS) Precentral sulcus Precentral gyrus Central sulcus Postcentral sulcus Pars bracket

26. NP/MGH Central sulcus Postcentral sulcus Central sulcus Central sulcus Postcentral sulcus Postcentral sulcus Pars bracket Pars bracket

27. NP/MGH Thin post-CG sign the postcentral gyrus is thinner than the precentral gyrus (98%). The Central Sulcus (CS) Precentral gyrus Postcentral gyrus

28. NP/MGH Intraparietal Sulcus (IPS) and the post-CS in axial MRI, the IPS intersects the post-CS (99%). The Central Sulcus (CS) Pars bracket IPS Postcentral sulcus IPS Pars bracket

29. NP/MGH Postcentral sulcus IPS Postcentral sulcus IPS Postcentral sulcus IPS

30. NP/MGH Precentral sulcus Superior frontal sulcus Precentral gyrus Central sulcus Superior frontal gyrus Midline Sulcus sign the most prominent convexity sulcus that reaches the midline interhemispheric fissure is the CS (70%). The Central Sulcus (CS)

31. NP/MGH The Central Sulcus (CS)

32. Superior and Inferior Temporal Sulci Superior Temporal Sulcus (red) -divides superior temporal gyrus (peach) from middle temporal gyrus (lime) Inferior Temporal Sulcus (blue) -not usually very continuous -divides middle temporal gyrus from inferior temporal gyrus (lavender)

33. Superior and Inferior Frontal Sulci Superior Frontal Sulcus (red) -divides superior frontal gyrus (mocha) from middle frontal gyrus (pink) Inferior Frontal Sulcus (blue) -divides middle frontal gyrus from inferior frontal gyrus (gold) orbital gyrus (green) and frontal pole (gray) also shown Frontal Eye fields lie at this junction

34. Medial Frontal Sulcus lies between the mid-sagittal line and the Superior Frontal sulcus and has the Precentral sulcus as its posterior margin The portion on the lateral surface of the hemisphere is usually more or less completely subdivided into an upper and a lower part by an antero -posterior sulcus, the paramedial sulcus, which, however, is frequently interrupted by bridging gyri . frontal pole (gray) and orbital gyrus (green) also shown

35. Cortical Homunculus

36. NP/MGH Sagittal Neuroanatomy

37. 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

38. 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

39. 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

40. 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

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

42. 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

43. NP/MGH Axial Neuroanatomy

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

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

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

47. 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

48. NP/MGH Superior Temporal gyrus Middle Temporal gyrus Gyrus rectus Olfactory sulcus Medial orbital gyrus Anterior orbital gyrus Posterior orbital gyrus Lingual gyrus Parahippocampal gyrus Calcarine sulcus Cuneus Gyrus descendens Temporo-occipital fissure Middle occipital gyrus Intra-occipital sulcus

49. NP/MGH Superior frontal gyrus Anterior orbital gyrus Posterior orbital gyrus Frontomarginal gyrus Cingulate gyrus Superior occipital gyrus Intra-occipital sulcus Middle occipital gyrus

50. 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

51. 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

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

53. 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

54. 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

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

56. NP/MGH Central sulcus Postcentral sulcus Superior frontal sulcus Precentral sulcus Pars marginalis Intraparietal sulcus Superior frontal gyrus Middle frontal gyrus Precuneus Paracentral lobule Superior parietal gyrus

57. NP/MGH Coronal Neuroanatomy

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

59. 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

60. 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

61. 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

62. NP/MGH Superior Frontal gyrus Middle Frontal gyrus Superior Temporal gyrus Middle Temporal gyrus Superior Temporal Sulcus Sylvian Fissure Heschl’s gyrus Inferior Temporal sulcus Inferior Temporal gyrus Amygdala Ambient gyrus Entorhinal area Cingulate gyrus Superior Frontal sulcus Precentral sulcus Precentral gyrus

63. 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

64. 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

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

66. 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

67. NP/MGH Lingual gyrus Calcarine sulcus Superior parietal lobule precuneus Cingulate gyrus Tentorium cerebelli Fusiform gyrus Inferior parietal lobule Middle occipital gyrus Inferior occipital gyrus Lingual gyrus Collateral sulcus

68. Cerebral Arteries & Veins

69. Anatomy and Vascular Territories of the 3 Main Cerebral Arteries: Middle Cerebral Artery

70. Anatomy and Vascular Territories of the 3 Main Cerebral Arteries: Anterior Cerebral Artery

71. Anatomy and Vascular Territories of the 3 Main Cerebral Arteries: Posterior Cerebral Artery

72. Cortical Areas Supplied by the MCA, ACA and PCA

73. Superficial and Deep Arterial Supply to the Cerebral Hemispheres Coronal Plane

74. Superficial and Deep Arterial Supply to the Cerebral Hemisphere Axial Plane

75. Lenticulostriate Arteries Supply the Basal Ganglia and Internal Capsule

76. Arterial Supply of the Thalamus and Basal Ganglia

77. Circle of Willis •Internal carotid and vertebrals anastomoze in the Circle of Willis

78. Venous Sinuses Cerebral veins drain into venous sinuses and into internal jugular vein Superficial veins lie on surface of cortex and drain into superior sagittal sinus Deep veins drain internal structures and empty into the straight sinus See Nolte, J. The Human Brain

79. Venous Sinuses The walls of the dural venous sinuses are composed of dura mater lined with endothelium, a specialized layer of flattened cells found in blood vessels. They differ from other blood vessels in that they lack a full set of vessel layers (e.g. tunica media) characteristic of arteries and veins. It also lacks valves as seen in veins.

80. Thank You