○ Arachnoid granulation: Connects the dura mater and arachnoid mater. Grain-like. A structure surrounded by the thinned dura mater. Protrudes into the space of the superior sagittal sinus or lateral venous lacunae

○ Arachnoid trabeculae: Connects the arachnoid mater and pia mater

○ Subarachnoid space: Much larger than the subdural space. Cerebrospinal fluid flows here (→ an additional mechanism to protect the brain), pathway for exchange of materials between cerebrospinal fluid and veins

○ Exchange of materials between cerebrospinal fluid and veins is restricted by the blood-brain barrier (BBB)

○ Cerebrospinal fluid enters the subarachnoid space through three holes (two sides, one bottom) in the fourth ventricle

○ Subarachnoid cisternae: Relatively wide areas of the subarachnoid space along the brain’s convolutions. Includes the following types:

○ Sylvian cistern

○ Supracallosal cistern (cistern of the corpus callosum)

○ Superior cistern (cisterna ambiens)

○ Interpeduncular cistern

○ Cerebellomedullary cistern (cisterna magna)

○ Pia mater: Delicate

○ Neuroglial membrane: Connects the pia mater and the brain’s cortex

○ Major meninges

○ Falx cerebri: 〈sagittal view〉 The falx cerebri can be seen in the sagittal view of the dura mater

Figure 3. Brain enclosed by the dura mater

Figure 4. Sagittal view of the dura mater

falx cerebri, superior sagittal sinus, inferior sagittal sinus

Figure 5. Brain before and after removing the dura mater

○ Falx cerebelli

○ Tentorium cerebelli

○ Tentorial notch

○ Diaphragma sellae

② Spinal meninges

○ Pachymeninx (dura mater): Consists of the dura mater (①)

○ Dura mater = Endocranial layer + Epidural space + Meningeal layer

○ Leptomeninges: Composed of the arachnoid mater (②) and pia mater (③)

⑷ Cerebral circulation: A dual system

Figure 6. Brain Circulation

① Carotid System: Aorta → Common Carotid → Internal Carotid

○ Types

○ Anterior Cerebral Artery (ACA): One of the three major cerebral vessels

○ Middle Cerebral Artery (MCA): One of the three major cerebral vessels

○ Location

○ Anterior half of the thalamus

○ Corpus striatum

○ Internal capsule

○ Frontal lobe

○ Parietal lobe

○ Lateral aspect of the temporal lobe

② Vertebrobasilar System: Vertebral Artery → Basilar Artery

○ Types

○ Posterior Cerebral Artery (PCA): One of the three major cerebral vessels

○ Cerebellar Arteries: There are three types as follows

○ Superior Cerebellar Artery (SCA)

○ Anterior Inferior Cerebellar Artery (AICA)

○ Posterior Inferior Cerebellar Artery (PICA)

○ Location

○ Anterior half of thalamus

○ Corpus striatum

○ Internal capsule

○ Frontal lobe

○ Parietal lobe

○ Lateral portion of temporal lobe

③ Circle of Willis: A hexagonal ring of vessels that connects cerebral vessels to provide a bypass pathway. It is important because it creates an alternative cerebral blood flow when a cerebral vessel is blocked

○ Anterior Communicating Artery (AComm): Connects left and right circulation systems

○ Posterior Communicating Artery (PComm): Connects the internal carotid and posterior cerebral artery

○ Location

○ Rhombencephalon

○ Mesencephalon

○ Caudal part of the diencephalon

○ Occipital lobe

○ Inferior part of the temporal lobe

④ Sinus: Venous blood collects between the skull dura mater and the meningeal layers

○ Types of Sinuses

○ Superior Sagittal Sinus

○ Inferior Sagittal Sinus

○ Transverse Sinus

○ Straight Sinus

○ Occipital Sinus

○ Sigmoid Sinus

○ Cavernous Sinus

○ Superior Petrosal Sinus

○ Inferior Petrosal Sinus

○ Other Veins

○ Superior Cerebral Vein

○ Anterior Cerebral Vein

○ Superficial Middle Cerebral Vein

○ Anterior Cerebral Anastomotic Vein (Trolard)

○ Inferior Anastomotic Vein (Labbé)

○ Internal Cerebral Vein

○ Great Cerebral Vein

○ Basal Vein

2. Lateral Cortical Anatomy

Figure 7. View of the Left Cerebral Hemisphere from the Side

Figure 8. Schematic View of the Brain from the Side

⑴ Definition of Terms

Figure 9. Gyri, Sulci, Gray Matter, White Matter]

① Sulcus (⒮ sulcus, ⒫ sulci): Deeply indented part of the cortical surface

② Gyrus (⒮ gyrus, ⒫ gyri): Protruding part of the cortical surface

③ Gray Matter: Exists in the following tissues

○ Neuronal cell bodies

○ In the brain, it exists in the cortex

○ In the spinal cord, it exists in the horn

○ Cortex

○ Basal Ganglia

○ Thalamus

○ Other Nuclei

○ Spinal Ganglion

④ White Matter: Appears pink due to lipid content → turns white when treated with formaldehyde. Exists in the following tissues

○ Nerve Fibers (Axon)

○ In the brain, exists in the medulla: However, excluding the basal ganglia

○ In the spinal cord, exists in the cortex

⑤ Structure of the Brain: Gray Matter - White Matter - Gray Matter, Nerve Cell Body - Nerve Fibers (Axon) - Nerve Cell Body

Figure 10. Major Sulci of the Cerebrum

The part indicated by the arrow is the approximate location of the preoccipital notch

① Interhemispheric Fissure

Figure. 11. Top Surface of the Cerebrum and Interhemispheric Fissure

Figure 12. Schematic Top View of the Cerebrum

② Central Sulcus (CS): 〈lateral view〉 A deep sulcus that divides each cerebral hemisphere into front and back. 〈sagittal view〉 From the Parieto-Occipital Sulcus (POS) through a large sulcus → small sulcus → large sulcus → small sulcus → large sulcus leads to the Central Sulcus

③ Lateral Sulcus (LS) or Sylvian Fissure (SF): 〈lateral view〉 A sulcus that diagonally indents from the middle of the cerebral side surface upwards and downwards

○ Anterior Ramus: 〈lateral view〉 A small sulcus that extends shortly anterosuperior from the beginning of the Lateral Sulcus

○ Ascending Ramus: 〈lateral view〉 A small sulcus that extends shortly upwards right after the Anterior Ramus

○ Posterior Ramus: 〈lateral view〉 The main continuation of the Lateral Sulcus towards the back

④ Occipito-Temporal Sulcus: Responsible for processing information about faces and shapes. 〈sagittal view〉

⑤ Parieto-Occipital Sulcus (POS): 〈sagittal view〉

⑶ Frontal Lobe: 〈lateral view〉 Above the Lateral Sulcus, in front of the Central Sulcus

① Precentral Sulcus (PrS): 〈lateral view〉 A sulcus that lies parallel to and just in front of the Central Sulcus

② Precentral Gyrus (PrCG): 〈lateral view〉 The gyrus between the Central Sulcus and the Precentral Sulcus

③ Superior Frontal Gyrus (SFG)

④ Superior Frontal Sulcus (SFS)

⑤ Middle Frontal Gyrus (MFG)

⑥ Inferior Frontal Sulcus (IFS)

⑦ Inferior Frontal Gyrus (IFG): Orbital Part + Triangular Part + Opercular Part

Figure 13. Details of the Inferior Frontal Gyrus

○ Orbital Part (pars orbitalis): 〈lateral view〉 The front part of the anterior branch of the Lateral Sulcus

○ Triangular Part (pars triangularis): 〈lateral view〉 Between the anterior branch and the ascending branch of the Lateral Sulcus. Corresponds to Brodmann area 44. Constitutes Broca’s area

○ Opercular Part (pars opercularis): 〈lateral view〉 Between the ascending branch and the posterior branch of the Lateral Sulcus. Corresponds to Brodmann area 45. Constitutes Broca’s area

⑷ Temporal Lobe: 〈lateral view〉 Below the Lateral Sulcus, in front of the Occipito-Temporal Sulcus. 〈bottom view〉 The Occipito-Temporal Sulcus can be seen from the bottom view of the brain

① T#: Temporal Gyrus NO.

② Superior Temporal Gyrus (STG, T1): 〈lateral view〉 The gyrus that lies horizontally at the very top of the Temporal Lobe

③ Superior Temporal Sulcus (STS): 〈lateral view〉 The sulcus between the Superior Temporal Gyrus and the Middle Temporal Gyrus

④ Middle Temporal Gyrus (MTG, T2): 〈lateral view〉 The gyrus that lies parallel and just below the Superior Temporal Gyrus

⑤ Inferior Temporal Sulcus (ITS): 〈lateral view〉 The sulcus between the Middle Temporal Gyrus and the Inferior Temporal Gyrus

⑥ Inferior Temporal Gyrus (ITG, T3): 〈lateral view〉 The gyrus that lies parallel and just below the Middle Temporal Gyrus

⑦ Occipito-Temporal Gyrus (T4)

⑧ Parahippocampal Gyrus (T5): Located at the bottom central surface of the brain, laid out in a coronal plane

⑨ Insula, etc.

Figure 14. View of the Left Cerebral Hemisphere’s Lateral Surface with the Insula Cover Removed

Figure 15. Cortex Scraped from the Transverse Temporal Gyrus

Primary Auditory Cortex (auditory radiation) is located just below the Transverse Temporal Gyrus

Figure 16. Entire Insula Exposed

○ Opercula of Insula: Part of the Inferior Frontal Gyrus

○ Transverse Temporal Gyrus (Heschl’s Convolutions): Located immediately medial to the Superior Temporal Gyrus. Comprises Brodmann areas 41, 42

○ Auditory Radiation: The medulla of the Transverse Temporal Gyrus. Primary Auditory Cortex

○ Insula: 〈lateral view〉 Another triangular cortical area hidden by the Inferior Frontal Gyrus. 〈coronal view〉 Clearly visible in the coronal view

○ Circular Sulcus: 〈lateral view〉 Surrounds the insula

○ Central Sulcus of Insula: 〈lateral view〉 Deeply crosses the middle of the insula

○ Short Insular Gyri: 〈lateral view〉 Located anterior to the central sulcus of the insula

○ Long Insular Gyri: 〈lateral view〉 Located posterior to the central sulcus of the insula

○ Limen Insula: 〈lateral view〉 At the lower tip of the insula, close to the anterior perforated substance. This area lacks the circular sulcus

⑩ Temporal Pole

⑸ Parietal Lobe: 〈lateral view〉 Above the central sulcus, in front of the parieto-occipital sulcus (POS). 〈sagittal view〉 The parieto-occipital sulcus can be seen in the brain’s sagittal view

① Postcentral Sulcus (PoS): 〈lateral view〉 Located immediately behind and parallel to the central sulcus

② Postcentral Gyrus (PoCG): 〈lateral view〉 The gyrus between the central sulcus and the postcentral sulcus

③ Intraparietal Sulcus

④ Superior Parietal Lobule (SPL): 〈lateral view〉 The area behind the postcentral gyrus in the parietal lobe, above the intraparietal sulcus

⑤ Inferior Parietal Lobule (IPL): Supramarginal Gyrus + Angular Gyrus. 〈lateral view〉 The area behind the postcentral gyrus in the parietal lobe, below the intraparietal sulcus

○ Supramarginal Gyrus (SMG): 〈lateral view〉 The gyrus wrapping around the end of the lateral sulcus

○ Angular Gyrus (AG): 〈lateral view〉 The sulcus wrapping around the ascending terminal part of the superior temporal sulcus. Formed by the combination of the superior and middle temporal gyri

⑹ Occipital Lobe: 〈lateral view〉 Above the parieto-occipital sulcus (POS), behind the occipito-temporal sulcus

① Lateral Occipito-temporal Gyrus (LOG)

② Occipital Pole

3. Medial Cortical Anatomy

Figure 17. Left medial side of the brain

rostrum, genu, splenium, anterior commissure, parolfactory gyrus, lamina terminalis & paraterminal gyrus, cuneus, precuneus, lingual gyrus, calcarine gyrus

Figure 18. Left medial side of the brain

Figure 19. Left medial side of the brain]

Figure 20. Right medial side of the brain

Figure 21. Right medial side of the brain

1, hippocampus; 2, parahippocampal gyrus (T5); 3, fusiform gyrus(occipito-temporal gyrus) (T4); 4, inferior temporal gyrus (T3); 5, calcarine sulcus; 6, occipital lobe(cuneus); 7, parietal lobe (precuneus); 8, cingulate gyrus; 9, medial frontal gyrus; 10, corpus callosum; 11, body of fornix, 12, thalamic nucleus

Figure 22. Schematic of the right medial side of the brain

⑴ Ventricle

Figure 23. Position of the ventricles

interventricular foramen

Figure 24. Position of the ventricles

① Lateral Ventricle (1st and 2nd ventricles)

○ Medial Aspect = Body + Anterior Horn + Posterior Horn + Inferior Horn

○ Body

○ Anterior Horn

○ Posterior Horn

○ Bulb of Occipital Horn: The protrusion on the inner wall of the posterior horn due to the occipital forceps

○ Bird’s claw spur (calcar avis): The part of the inner wall of the posterior horn that is raised due to the bird’s claw groove

○ Inferior horn

○ Choroid fissure: 〈back view〉 《Posterior occipital lobe, horizontal section of lower temporal lobe》《Coronal section of cerebellum》 A groove that enters the inferior horn of the lateral ventricle from the lateral side of the medial and lateral geniculate nuclei

○ Collateral trigone: 〈sagittal view〉 The area where the body of the lateral ventricle splits into the posterior horn and inferior horn

② Interventricular foramen: 〈sagittal view〉 A relatively large opening located anterior to the 3rd ventricle. It serves as a pathway connecting to the lateral ventricles

③ 3rd ventricle

④ Cerebral aqueduct: The connection pathway between the 3rd and 4th ventricles. Located vertically in the midbrain

○ Colliculus (⒮ colliculus, ⒫ colliculi) or tectal plate (quadrigeminal plate): A protruding structure located at the back wall of the midbrain aqueduct

○ Superior colliculus: Involved in vision

○ Inferior colliculus: Involved in hearing

⑤ 4th ventricle

⑥ Central canal

⑦ Choroid plexus: Surrounded by blood vessels and secretes cerebrospinal fluid (CSF). Composed of pia mater. 〈 sagittal view〉 A structure crumpled inside the lateral ventricle. Extensively formed across the inferior and posterior horns of the lateral ventricle. Connects from the interventricular foramen to the amygdala

Figure 25. Appearance of the choroid plexus]

○ Cerebrospinal fluid: Flows through the lateral ventricle → 3rd ventricle → 4th ventricle

○ CSF pressure: About 10% of blood pressure

○ Cerebrospinal fluid has a lower pH than blood

⑵ Corpus callosum (CC): 〈 sagittal view 〉《Section》 The cross fibers that connect both cerebral hemispheres. A pathway for information exchange between the cerebral hemispheres

Figure 26. Dissected view showing the corpus callosum

① Structure: 〈sagittal view〉 Beak (front, rostrum) + knee (front, genu) + body (body) + Splenium (back, splenium)

② Indusium griseum: A thin layer of gray matter lightly covering the surface of the corpus callosum. Significantly thinner than other cortex layers

○ Lateral longitudinal striae and medial longitudinal striae: 〈top view〉 《Section》 Thin bands of nerve fibers visible to the naked eye along the surface of the corpus callosum

○ On the surface of the corpus callosum, there are visibly thin bands of lateral longitudinal striae and medial longitudinal striae

③ Septum pellucidum: 〈sagittal view〉 A thinly visible structure under the corpus callosum. Forms the inner walls of the lateral ventricles

○ Cavum septi pellucidi: The space between the left and right septum pellucidum

④ The size of the exposed corpus callosum can classify the brain’s sagittal view image

⑶ Callosal sulcus, etc.

① Callosal sulcus: 〈sagittal view〉 The sulcus that runs just above the corpus callosum

② Cingulate gyrus: 〈sagittal view〉 The gyrus located parallel to and above the corpus callosum, right next to the callosal sulcus

③ Cingulate sulcus: 〈sagittal view〉 The sulcus located just above the cingulate gyrus

④ Marginal Sulcus: 〈sagittal view〉 A sulcus that runs parallel to the callosal sulcus and extends upwards near the splenium of the corpus callosum to form.

⑤ Paracentral lobule: 〈sagittal view〉 The anterior boundary is the precentral sulcus extended to the medial surface of the cerebrum. The posterior boundary is the marginal sulcus continuous with the paracentral sulcus. Divided by the central sulcus.

⑷ Parieto-occipital sulcus, etc.

① Parieto-occipital sulcus

② Precuneus (PCu): 〈sagittal view〉 The parietal lobe between the marginal sulcus and the parieto-occipital sulcus. 〈temporal view〉 Continuous with the superior parietal lobule.

③ Calcarine fissure (CF, calcarine sulcus): 〈sagittal view〉 A sulcus that runs anteriorly and posteriorly below the splenium of the corpus callosum. Meets the parieto-occipital sulcus in a Y shape during its course. Divides the occipital lobe into above (cuneus) and below (lingual gyrus).

④ Cuneus (Cu)

⑤ Lingual gyrus (LG)

⑸ Diencephalon

① Epithalamus: Connected from the fastigium-superior cerebellar peduncle-superior medullary velum-inferior colliculus-superior colliculus-posterior commissure-pineal gland-habenular commissure. 〈sagittal view〉 Brown area above the thalamus.

○ Posterior commissure: Forms the posterior boundary of the third ventricle.

○ Pineal gland (pineal body): Attached to the diencephalon by stalks above and below.

○ Habenular commissure: Included in the upper wall of the pineal gland stalk. A bundle of crossing fibers connecting the habenular nuclei of the left and right cerebrum.

○ Habenular trigone: 〈back view〉 A sunken triangular structure attached to the pineal gland, located above the superior colliculus and below the pulvinar. Contains medial and lateral habenular nuclei.

○ Stria medullaris of thalamus: A bundle of nerve fibers that differentiates the medial and upper surfaces of the thalamus. Contains afferent neurons entering the habenular nucleus.

○ Roof of 3^rd ventricle: Membrane above the pineal gland.

② Thalamus: 〈sagittal view〉 Upper protrusion of grey matter forming the lateral wall of the third ventricle. About 4 cm in egg shape. The upper surface of the thalamus is the floor of the lateral ventricle. Most sensory nerves pass through here.

○ Interthalamic adhesion (massa intermedia): About 80% of people have the inner surfaces of both thalami partially fused. 〈sagittal view〉 Circular area protruding above the thalamus.

○ Stria medullaris of thalamus: 〈sagittal view〉 Striped structure on top of the thalamus.

○ Stratum zonale: 〈sagittal view〉 White matter covering the upper surface of the thalamus.

○ Stria terminalis: 〈sagittal view〉 A band of white fiber extending from the floor of the body part of the lateral ventricle to the anterior of the hypothalamus, next to the thalamostriate vein. A landmark demarcating the boundary between the thalamus and caudate nucleus. 〈horizontal view〉 Located laterally right next to the attachment of the choroid plexus on the roof of the inferior horn.

○ Centromedian parafascicular complex

○ Pulvinar: 〈back view〉 The posterior end of the thalamus protruding posterolaterally. The pineal gland is located between the left and right pulvinar.

Figure 27. Pulvinar and adjacent structures]

○ Motor thalamus = VAN (ventral anterior nucleus) + VLN (ventral lateral nucleus)

○ Sensory thalamus

○ Lateral geniculate nucleus/body (LGN): 〈back view〉 Located below and lateral to the pulvinar. Responsible for vision.

○ Medial geniculate nucleus/body (MGN): 〈back view〉 Located slightly below or below the pulvinar, lateral to the arm of the superior colliculus. Responsible for hearing.

○ VPN (ventral posterior nucleus): Responsible for general sensation.

○ Limbic thalamus = AN (anterior nucleus) + DN (dorsomedial nucleus)

③ Hypothalamus: 〈sagittal view〉 The lower triangular part forming the floor and the lower lateral walls of the third ventricle. Forward to the optic chiasm, backward to the mammillary body, and laterally to the optic tract.

○ Hypothalamic sulcus: 〈sagittal view〉 A shallow sulcus formed above the hypothalamus at the line where the midbrain aqueduct connects. Corresponds to the sulcus limitans of the embryonic neural tube.

○ Pituitary gland (neurophophysis)

○ Infundibulum: 〈sagittal view〉 The part that connects the pituitary gland to the brain floor.

④ Subthalamus: Located behind the hypothalamus. The red nucleus and substantia nigra extend into the caudal subthalamus region.

⑹ Mammillary body: A round structure located under the thalamus.

⑺ Lamina terminalis: 〈sagittal view〉 The anterior wall of the hypothalamus in the median plane of the cerebrum. Thin band. Connected to the anterior commissure.

① Paraterminal gyrus: 〈sagittal view〉 Small grey matter existing anteriorly attached to the lamina terminalis.

② Posterior parolfactory sulcus: 〈sagittal view〉 A sulcus forming the anterior boundary of the paraterminal gyrus.

③ Parolfactory gyrus: 〈sagittal view〉 Located below the rostrum of the corpus callosum, in front of the posterior parolfactory sulcus.

④ anterior parolfactory sulcus: 〈sagittal view〉 the sulcus forming the anterior boundary of the olfactory tract

4. Basal Cortical Anatomy

Figure 28. Cerebral basal surface

Figure 29. Cerebral basal surface

Figure 30. Cerebral basal surface

Figure 31. Left cerebral hemisphere basal surface

uncas, rhinal sulcus, red nucleus, substantia nigra

Figure 32. Anterior cerebral basal surface

rectus gyrus, orbital gyrus, optic tract

Figure 33. Anterior cerebral basal surface

⑴ Optic chiasm: The fibers running on the outside of the optic nerves cross at the optic chiasm and then follow the same side’s visual path, while the fibers running on the inside cross to the opposite side’s visual path at the optic chiasm. 〈front view〉 Behind the end of the olfactory path, a structure in the shape of an X

⑵ Optic tract : 〈bottom view〉 A thick band-like structure located posterolaterally from the optic chiasm

⑶ Lateral ventricle

⑷ Olfactory tract : 〈front view, bottom view〉 A band running back and forth near the midline on the underside of the cerebrum, one on each side

⑸ Olfactory bulb : 〈front view〉 The very front end of the olfactory tract. A slightly rounded bulging part

⑹ Olfactory trigone: 〈bottom view〉 The end part of the olfactory tract. Triangular shape

⑺ Perforated substance: A structure with several holes through which blood vessels pass

① Anterior perforated substance: 〈bottom view〉 Positioned anteriorly to the olfactory trigone, lateral olfactory striae, medial olfactory striae, medially to the optic chiasm, optic tract, posteriorly to the uncus

② Posterior perforated substance

⑻ Olfactory striae

① Lateral olfactory striae: 〈bottom view〉 The nerve fibers of the olfactory tract mostly follow the lateral olfactory striae to the lateral olfactory area

○ Lateral olfactory area: The area that receives neural stimuli through the lateral olfactory striae. Corresponds to the primary olfactory cortex. The rhinal sulcus forms the lateral boundary

○ Prepiriform cortex = lateral olfactory gyrus + cortex of limen insulae

○ Lateral olfactory gyrus: A thin layer of grey matter covering the lateral olfactory striae

○ Cortex of limen insulae (gyrus ambiens): The layer of grey matter on the surface of the limen insulae. Located medially to the lateral olfactory gyrus

○ Periamygdaloid cortex = gyrus semilunaris + uncus

○ Gyrus semilunaris: The lateral olfactory striae bend from the limen insulae posteromedially to connect with the gyrus semilunaris

○ Uncus

○ Entorhinal cortex: Located superiorly to the prepiriform cortex and inferiorly to the parahippocampal gyrus

② Intermediate olfactory striae: 〈bottom view〉 Some of the nerve fibers of the olfactory tract go to the anterior perforated substance along the intermediate olfactory striae

○ Intermediate olfactory area: The area into which the intermediate olfactory striae enter the anterior perforated substance

③ Medial olfactory striae: 〈bottom view〉 A pronounced linear structure leading from the olfactory trigone to the septal area on the inner side of the cerebrum

④ Diagonal band of Broca: 〈bottom view〉 A wide bundle of fibers starting at the posterior end of the anterior perforated substance, passing right in front of the optic tract to the septal area in front of the terminal layer

⑼ Tuber cinereum: 〈bottom view〉 A triangular area surrounded by the optic chiasm in front, the optic tract on both sides, and the mammillary bodies behind

① Median eminence: The part where the tuber cinereum connects with the infundibulum below and in front

⑽ Frontal lobe basal surface

① Olfactory sulcus: 〈bottom view〉 The sulcus where the olfactory tract is located

② Straight gyrus (RG, rectus gyrus): 〈bottom view〉 A thin gyrus inside (medial) the olfactory sulcus

③ Orbital gyri: All the gyri next to the straight gyrus. 〈bottom view〉 Several irregular gyri located between the olfactory sulcus and the inferior temporal sulcus, on the orbital plane. Classified as follows depending on the location

○ Anterior orbital gyri

○ Posterior orbital gyri

○ Superior orbital gyri

○ Inferior orbital gyri

④ Orbital sulci: 〈bottom view〉 Several irregular sulci in the orbital gyri

⑾ Temporal lobe basal surface

① Hippocampal sulcus

② Parahippocampal gyrus: Located on the lower central surface of the brain, laid out in a sagittal plane

○ Isthmus: 〈sagittal view〉 Located just below (inferior) the corpus callosum enlargement. Continuous with the parahippocampal gyrus

③ Collateral sulcus: 〈bottom view〉 A sulcus extending from below (inferior) the lingual gyrus to the side of the medial occipitotemporal gyrus, dividing the parahippocampal gyrus and the medial occipitotemporal gyrus

④ Medial occipitotemporal gyrus

⑤ Occipitotemporal sulcus

⑥ Lateral occipitotemporal gyrus: 〈lateral view〉 Corresponds to the basal surface of the inferior temporal gyrus

⑦ Rhinal sulcus: 〈bottom view〉 An extension of the collateral sulcus (collateral sulcus) anteriorly. Forms the lateral boundary of the entorhinal area, an internal extension of the parahippocampal gyrus

5. White Matter Anatomy

Figure 34. Left cerebral hemisphere white matter

Figure 35. Left cerebral hemisphere white matter

Figure 36. Left cerebral hemisphere white matter

⑴ Association fiber: Fibers that connect different parts of the same cerebral hemisphere. These are the closest connecting nerve fibers, thus located most laterally.

① Short association fiber: Connects adjacent gyri, appearing U-shaped along the gyri and thus also called U fibers. 〈sagittal view〉

② Longitudinal fasciculus

○ Superior longitudinal fasciculus, arcuate fasciculus: Divided into 1, 2, 3. 〈sagittal view〉 Curves around the insula from the superolateral aspect of the cerebrum into the temporal lobe. A type of long association fiber that connects the frontal, parietal, occipital, and temporal lobes, mainly linking the frontal and occipital lobes.

○ Inferior longitudinal fasciculus: 〈sagittal view〉 Connects the temporal pole with the occipital pole, linking the temporal and occipital lobes.

③ Occipitofrontal fasciculus

○ Connects the frontal and occipital lobes: Extends the farthest.

○ Superior occipitofrontal fasciculus: 〈sagittal view〉 Present on the inner surface of the lateral ventricle.

○ Inferior occipitofrontal fasciculus: 〈sagittal view〉 Located superomedially to the uncinate fasciculus and beneath the external capsule, connecting the frontal and occipital lobes.

○ Recent studies on monkey brains consider the inferior occipitofrontal fasciculus to be non-existent.

○ The anterior part of the inferior occipitofrontal fasciculus is considered to be the extreme capsule fasciculus, and the posterior part the inferior longitudinal fasciculus.

④ Uncinate fasciculus: 〈sagittal view〉 A dense fiber bundle that connects the area around the hippocampus in the temporal lobe with the basal surface of the frontal lobe, hook-shaped.

⑤ Cingulate fasciculus, cingulum: Connects the limbic lobe. 〈sagittal view〉 Part of the cingulate gyrus’s substance. Starts on the inner surface of the corpus callosum and enters into the parahippocampal gyrus following the corpus callosum.

⑵ Commissural fiber: Fibers that connect corresponding areas of the two cerebral hemispheres.

① Corpus callosum: The largest of the commissural fibers.

○ Forceps minor or frontal forceps: 〈sagittal view〉 Fibers extending inward from the genu of the corpus callosum.

○ Forceps major or occipital forceps: 〈sagittal view〉 Fibers extending backward from the splenium of the corpus callosum.

○ Tapetum: 〈sagittal view〉 A layer of myelinated fibers extending vertically from the trunk and splenium of the corpus callosum, thus connected to the corpus callosum fibers. Forms the roof and lateral walls of the posterior horn of the lateral ventricle and the lateral wall of the inferior horn.

② Anterior commissure (AC): The second largest commissural fiber, connecting the amygdala and the temporal lobes. 〈sagittal view〉 A globular structure located just behind the terminal stria and lateral to the terminal gyrus.

③ Posterior commissure (PC): 〈sagittal view〉 Present in globular form near the junction of the third ventricle and the midbrain aqueduct.

Figure 37. Posterior commissure

④ Habenular commissure

⑶ Projection fiber: Fibers that extend from the cerebrum to lower regions such as the midbrain and pons, reaching the farthest and thus located most medially.

① Internal capsule: 〈coronal view〉 The thalamus and caudate nucleus are medial, and the lentiform nucleus is lateral.

○ Anterior limb: 〈coronal view〉 Between the caudate nucleus and lentiform nucleus.

○ Genu: 〈coronal view〉 Medial to the apex of the lentiform nucleus.

○ Posterior limb: 〈coronal view〉 Between the lentiform nucleus and thalamus.

○ Retrolenticular part: Located behind the lentiform nucleus.

○ Sublenticular part: Located beneath the part behind the lentiform nucleus.

② Corona radiata: 〈sagittal view〉 《Cutaway》 The nerve fibers from the internal capsule fan out like a corona. Crosses the fibers of the corpus callosum at right angles.

③ Optic radiation: 〈sagittal view〉 《Cutaway》 The most posterior fibers of the internal capsule extend to the visual area of the occipital lobe, near the calcarine sulcus. Forms the lateral wall of the posterior horn of the lateral ventricle.

○ Superior fibers: 〈sagittal view〉 Follow a nearly straight path from the lateral geniculate body to the visual cortex.

○ Inferior fibers: 〈sagittal view〉 Proceed anteroinferiorly from the lateral geniculate body, forming Meyer’s loop in front of the anterior part of the inferior horn of the lateral ventricle, then turn posteriorly close to the external sagittal stratum to reach the visual cortex.

○ Meyer’s loop: 〈sagittal view〉 Located medially to the uncinate fasciculus in front of the anterior part of the inferior horn of the lateral ventricle.

④ Fornix

⑷ Striatal fiber

6. Limbic system

Figure 38. Schematic of the limbic system

Figure 39. Detailed schematic of the limbic system

Limbic sulcus; 1, Cingulate sulcus; 2, Subparietal sulcus; 3, Anterior calcarine sulcus; 4, Collateral sulcus; 5, Rhinal sulcus; Limbic gyrus; 6, Subcallosal gyrus; 7, Cingulate gyrus; 7’, Isthmus; 8, Parahippocampal gyrus; 9, Anterior segment of the uncus; Intralimbic gyrus (indicated by dotted lines); 10, Prehippocampal rudiment or precommissural hippocampus; 11, Indusium griseum or supracommissural hippocampus; 12, Hippocampus or retrocommissural hippocampus; Other major structures; 13, Mammillary body; 14, Anterior perforated substance; 15, Anterior commissure; 16, Septal nuclei covered by the paraterminal gyrus; 17, Precommissural fornix; 18, Postcommissural fornix or anterior column; 19, Mammillothalamic tract; 20, Anterior thalamic nucleus; 21, Medial thalamic nucleus; 22, Body of fornix; 23, Corpus callosum; 24, Crus of fornix (Source: Professor Jung Cheon-gi, Seoul National University College of Medicine, Structure and Function of the Human Brain course).

⑴ Characteristics of the limbic system

① More developed in higher animals

② Related to emotions, behavior, and memory formation

③ Information flow: Thalamus → various cerebral cortices → hippocampus → recognition of new information → short-term storage in the cerebral cortex

⑵ Fornix: Consists of crura + body + columns. 〈sagittal view〉 Located beneath the transparent septum below the corpus callosum, connecting anteriorly to the mammillary bodies and posteriorly to the hippocampus at the temporal pole.

Figure 40. Structure of the fornix

Uncus, 2. Hippocampus, 3. Fimbriae of hippocampus, 4. Crus, 5. Commissure of fornix, 6. Body of fornix, 7. Column of fornix, 8. Mammillary body

① Fornix crura: 〈sagittal view〉 Located beneath the splenium of the corpus callosum, in pairs.

○ Hippocampal commissure: Connects the left and right fornix crura anterior to the splenium of the corpus callosum.

② Fornix body: 〈sagittal view〉 Merged into one structure.

③ Fornix columns: 〈sagittal view〉 Connected to the beak of the corpus callosum, in pairs. Consists of the exposed part (pars libera of columna fornicis) and the covered part (pars tecta of columna fornicis).

④ Mammillary bodies: 〈sagittal view〉 A globular structure located inferior to the hypothalamus, visible only after removing the hypothalamic substance. 〈bottom view〉 Located posterior to the grey commissure and anterior to the pons.

⑤ Hippocampus

⑥ Mammillothalamic tract: 〈sagittal view〉 Connects the mammillary bodies with the anterior nuclei of the thalamus.

⑦ Mammillotegmental tract: 〈sagittal view〉 Located posterior to the mammillothalamic tract and anterior to the fornix columns, easily damaged during dissection.

⑶ Hippocampal formation: An arc-shaped structure extending from the interventricular foramen to the anterior end of the inferior horn of the lateral ventricle.

Figure 41. Location and schematic of the hippocampus

Figure 42. Development process of the dentate gyrus (dotted line) and nomenclature within the hippocampus (A and B)]

Hippocampus, 2. Fimbria, 3. Lateral geniculate body, 4. Choroid fissure and tela choroidea, 5. Stria terminalis, 6. Tail of the caudate nucleus, 7. Temporal horn and choroid plexus, 8. Collateral eminence, 9. Collateral sulcus, 10. Parahippocampal gyrus, 11. Entorhinal area
Ambient cistern, 13. Mesencephalon (Midbrain), 14. Parasubiculum, 15. Presubiculum, 16. Subiculum proper, 17. Prosubiculum, 18. Transverse fissure

Figure 43. Structure of the hippocampus

Cornu Ammonis (Ammon’s Horn): 1. Alveus of the hippocampus, 2. Stratum oriens, 3. Stratum pyramidale, 3. Stratum lucidum, 4. Stratum radiatum, 5. Stratum lacunosum, 6. Stratum moleculare, 7. Hippocampal sulcus, 7’. Residual cavity

Dentate Gyrus: 8. Stratum moleculare, 9. Stratum granulosum, 10. Polymorphic layer, 11. Fimbria of the hippocampus, 12. Margo denticulatus, 13. Fimbriodentate sulcus, 14. Hippocampal sulcus, 15. Subiculum

Figure 44. Structure of the hippocampus

1, choroid plexus; 2, fimbria; 3, hippocampus; 4, hippocampal sulcus(up to the dentate gyrus, below the parahippocampal gyrus); 5, brainstem; 6, occipito-temporal sulcus; 7, collateral sulcus; 8, parahippocampal gyrus; 9, inferior temporal gyrus; 10, fusiform gyrus

Figure 45. Brainstem and hippocampus

① The upper part of the hippocampus is largely degenerated, including the gray layer (indusium griseum) and longitudinal striae.

② Hippocampal gyrus

③ Parahippocampal gyrus (PHG): 〈sagittal view〉 Medially, it is located between the hippocampal sulcus and the rhinal sulcus on the lateral side. Positioned between the collateral sulcus. Connected to the cingulate gyrus towards the posteromedial.

○ Cornu Ammonis (CA, corpus ammonis): Named after the horns of Amun in mythology due to its similar shape. Divided into four areas: CA1 ~ CA4.

○ Uncus: 〈sagittal view〉 The anterior end of the parahippocampal gyrus is expanded into a hook shape. 〈bottom view〉 Connected to the semilunar gyrus on the superior side.

④ Hippocampal sulcus (hippocampal fissure): 〈sagittal view〉 Forms the superomedial boundary of the parahippocampal gyrus. 〈coronal view〉 A shallow sulcus located medially and below the dentate gyrus.

⑤ Hippocampus (Hi): 〈sagittal view 〉 Forms a gray matter bulge along the entire length of the horn of the lateral ventricle, disappearing at the corpus callosum enlargement area. Paleocortex or archicortex lacks sulci and gyri, hence the hippocampus, being an archicortex, does not have the 6-layer structure like other neocortex and lacks sulci and gyri.

○ Hippocampal formation in a broad sense: CA (corpus ammonis) + dentate gyrus + subiculum

○ Hippocampus in a narrow sense: CA

○ Pes hippocampi: 〈sagittal view〉 The area where the hippocampus expands forward.

○ Hippocampal digitations: 〈sagittal view〉 The large and small bulges excluding the pes hippocampi.

⑥ Alveus of the hippocampus (alveus, alveus hippocampi): 〈sagittal view〉 A thin layer of white matter covering the ventricular surface of the hippocampus. Thickens medially to form the fimbria.

⑦ Fimbria of the hippocampus (fimbria, fimbria hippocampi): 〈sagittal view〉 A thick band of white matter along the medial edge of the hippocampus. Connects to the fornix at the corpus callosum enlargement area. Forms the choroid fissure along with the ventricular roof. The choroid plexus attaches here. Embedded within the substance, visible only after removal of the thalamus and mammillary bodies. Connected to the brain arch bridge.

⑧ Dentate gyrus: 〈sagittal view〉 Located above the parahippocampal gyrus and below the fimbria, resembling a row of teeth in shape. The uncus is positioned anteriorly, embedded within the substance, visible only after removal of the thalamus and mammillary bodies.

○ Gyrus fasciolaris (fasciola cinerea): 〈sagittal view〉 Located posteriorly above the dentate gyrus. A ridge structure continuing under the corpus callosum enlargement, connected to the gray layer above the corpus callosum.

⑨ Subiculum: The tail of the hippocampal formation. The transition area from the hippocampal sulcus to the parahippocampal gyrus.

⑩ Fusiform gyrus: Responsible for processing information about faces and shapes. 〈coronal view〉 Located between the parahippocampal gyrus and the inferior temporal gyrus.

○ Fusa: Anterior fusiform gyrus

7. Basal ganglia = Corpus striatum + subthalamic nucleus + substantia nigra + amygdala

Figure 46. Coronal section of the cerebrum]

Corpus Callosum, 2. Lateral Ventricle, 3. 3rd Ventricle, 4. Cortex of Insula, 5. Optic Tract, 6. Anterior Commissure, 7. Column of Fornix, 8. Caudate Nucleus, 9. Putamen, 10. Globus Pallidus, 11. External Medullary Lamina of Globus Pallidus, 12. Internal Medullary Lamina of Globus Pallidus, 13. Claustrum, 14. Hippocampus, 15. Amygdala, 16. Extreme Capsule, 17. External Capsule, 18. Internal Capsule,
Septum Pellucidum

Figure 47. Coronal section of the cerebrum

Corpus Callosum, 2. Lateral Ventricle, 3. Cortex of Insula, 4. Medial Geniculate Body, 5. Lateral Geniculate Body, 6. Diencephalic Reticular Formation, 7. Thalamus, 8. Fornix, 9. Tail of the Caudate Nucleus, 10. Hippocampus, 11. Alveus of Hippocampus, 12. Fimbria of Hippocampus, 13. Internal Capsule, 14. Middle Cerebellar Peduncle

Figure 48. Coronal section of the cerebrum]

Figure 49. Schematic diagram of the interior of the cerebrum]

Longitudinal cerebral fissure, 2. Corpus callosum, 3. Lateral ventricle, 4. 3rd ventricle, 5. Choroid plexus, 6. Calcar avis, 7. Calcarine sulcus, 8. Superior colliculus, 9. Inferior colliculus, 10. Pineal gland, 11. Medial geniculate nucleus, 12. Lateral geniculate nucleus, 13. Thalamus, 14. Stria medullaris of thalamus, 15. Pulvinar of thalamus, 16. Body of fornix, 17. Head of caudate nucleus, 18. Hippocampus, 19. Fimbria of hippocampus, 20. Internal capsule, 21. Septum pellucidum, 22. Cerebellum

⑴ Features: Regulates cerebral cortex activity, especially related to motor control

⑵ Corpus striatum: Lentiform nucleus + caudate nucleus. 〈sagittal view〉 The thalamus and lentiform nucleus are separated by the posterior limb of the internal capsule. A region in the basal ganglia primarily receiving information. Characterized by the striped appearance of white matter within.

① Caudate nucleus: Part of the basal ganglia, located above the lateral wall of the lateral ventricle.

② Lentiform nucleus: Putamen + globus pallidus

○ Putamen: 〈coronal view〉 Located in the outer segment of the lentiform nucleus, relatively dark gray matter resembling a shell. Part of the basal ganglia deeply embedded in the insular region.

○ Globus pallidus (pallidum): Appears darker in MRI images due to iron deposition. 〈coronal view〉 Located in the inner segment of the lentiform nucleus, relatively pale gray matter.

⑶ Subthalamic nucleus

⑷ Substantia nigra: Neurons in the substantia nigra send dopaminergic axons to the corpus striatum.

⑸ Amygdala (Am) : **〈coronal view〉** Ends the horn of the lateral ventricle anteriorly, densely packing the coronal cross-section in the temporal lobe.