Neurosurgery notes/Anatomy/Sensory/Visual/Optic pathways

Optic pathways

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Afferent visual system

  • The axons become myelinated after passing through openings in the sclera called the lamina cribrosa.
  • Retrobulbar optic nerve has three segments: intraorbital, intracanalicular in the optic canal, and intracranial just anterior to the optic chiasm
  • At the optic chiasm, more than half of the optic nerve axons decussate.
  • The retrochiasmal pathway consists of the optic tract, the lateral geniculate nuclei where the retinal ganglion cell axons synapse, the geniculocalcarine tracts in the temporal and parietal lobes, and the striate cortex in the occipital lobe.

Normal human visual field (for each eye)

  • Blind spot:
    • Due to absence of light receptors in the optic disc due to penetration of the retina by the optic nerve and vessels
    • Temporal side of the macular visual area
  • Normal visual field
    • In degrees from the central point is 60 degrees nasal, 50 degrees superiorly, and 90-100 degrees temporally
    • The nasal and temporal hemifields in each eye overlap but the monocular temporal crescent has no perimetric correlate in the fellow eye because the temporal visual field is larger than the nasal visual field, hence there are more crossing nasal fibers than there are ipsilateral temporal fibers with a 53:47 ratio.
  • The extra nasal fibers that cross accounts for the non-overlapping contralateral temporal crescent.
  • These fibers end up in the most anterior medial striate cortex and compromise 8-10% of the striate cortex.
  • This monocular representation in a retrochiasmal pathology is attributed to the monocular innervation in that area.
    • Thus, 30-40 degrees of the peripheral temporal visual field is unpaired and has unilateral representation in the contralateral visual cortex. Damage to this area of the visual cortex leads to the contralateral temporal crescent
notion image

Visual field testing

  • Confrontation
    • Do 4 quadrants with colour as a fast check
    • Do blind spot check with red pin as blind spot increases with papillodema
    • Absolute and relative scotoma
      • Red hat pin
        • Relative scotoma
        • Magnocellular pathways
      • White hat pin
        • Absolute scotoma
        • Parvocellular pathways
  • By perimetry with a tangent screen
    • Use the small red stimulus since desaturation of colour is an early sign of chiasmal compression
    • Types
        • Goldman perimetry
        • 160 degree testing
        How to interpret visual fields | Practical Neurology
        A diagram of a radar AI-generated content may be incorrect.
        This the left visual field.
        The blind spot is incoorporated into the Superior temporal and nasal quadranopia.
        Together with the right eye. The patient has a Right homonymous heminanopia that is incongruent (i.e. one is upper and one is lower quadrant)
        Goldman Perimetry - American Academy of Ophthalmology
        A diagram of a radar AI-generated content may be incorrect.
        The red line is the inner isomere.
        Blue line is the outer isomere.
        The 3 lines have different light intensity and light size.
        This image is of the right eye visual field as the n shaped blind spot is on the temporal side (the right side here)
        Automated Humphrey perimeter
        • HVF requires good patient cooperation to be valid
          • False negative: asleep
          • False positive: trigger happy
        • Central 60 degree
        • Has SD results
         
        Humphrey visual field analyser - Wikipedia
        a Eos Sr-qLe Fixate. Fixatim T*get Fixatim Losses: False POS Errors: False NEG Em's: Test Ck.ratm: Fig. Artarrs's Spot 12% White 3' asb SITA.Stardard GHT: pso: I esl Outside Normal L•mitS 828 dB 0.5% Pe2% Fixatim Monit«. Fintim F Los•: False POS Errors: F "e NEG Test .3 .2 .2 Total V. Biirxj Spot 5% Vesux Acuty: White 31.5 asb SITA.Star•dMd Anny•: VFI•. C)utside Normal omits 0 Q 3 Humphrey 24-2 SITA-Standard visual field test loss, conduced two days after MRF tests result for patient's left (a) and right (b) eyes, confirming a dense superior bitemporal field
        Humphrey visual field of patient’s left (A) and right (B) eyes.
        Humphrey field A is left eye and B is right eye.
        See Pituitary eye assessment
  • Estermann driving standards

Macular

  • Macular sparing in occipital cortex lesions is due to the dual blood supply from middle cerebral and posterior cerebral arteries to the occipital poles.
  • Sparing/splitting
    • Macular splitting: Lesions anterior or at/just posterior to the LGB, optic tract/radiation
    • Macular sparing: Lesions posterior to the LGB, primarily occipital cortex
    • Reasons for macula sparing in a PCA stroke causing homonymous heminanopia
      • Visual cortex has a dual blood supply, from the middle (MCA) and posterior (PCA) cerebral arteries or the posterior temporal and calcarine arteries.
      • Macula projects to two hemispheres hence
o Superior quadrant Inferior quadrant Superior retina Macula Inferior retina Superior (dorsal) trajectory Lateral geniculate nucleus Meyer's loop Geniculocalcarine tract Superior bank Caudal visual cortex Calcarine fissure Inferior bank Fibers representing macula
Macula doesn't flip and it takes 1/3 of the calcarine cortex for just a small area being covered
 

Knee of Von willie brand - Junctional scotoma

  • Central scotoma ipsilateral eye
  • Superior temporal quadranopia in contralateral eye/total vision loss in contralateral eye
• Anterior chiasmal syndrome Visual fields superonasal Inferonasal fibers Reuna Opbc Optic chiasm Optic tract Meyers LGB Optic radiatio Anterior Knee of Von-wille Brand superotemp Inferior temporal osterio Knee of Von- wille Brand
LGNu Laminae Red Crus cerebri MGNu pulNu pretectal Nu. Of Optic nerve Optic chiasm Optic tract Substantia nigra Medial lemniscus Meyers Loop MGNu sc.Br PulNu Oculomotor Nu. Optic radiations in retrolenticular [mb of internal capsule) LirV gyruS
 
Visual fields Orientation fo a" Levels overlapped for both eyes Visual fields for individual eyes Retinae Optic nerves Optic chiasm Optic nuclei c»tic radiations P rimary visual cortex Cuneus Calcarine suk:us

Lateral geniculate nucleus

Left eye Temporal hemiretina Left optic tract 2 3 4 5 6 Magnocellular pathway hemiretina Optic chiasm Right eye 2 3 4 5 6 Temporal hemiretina Right optic tract Lateral geniculate nucleus Parvocellular pathway Ventral Dorsal Primary visual cortex

Optic radiations (geniculocalcarine tract)

  • Formed by axons from neurons of
    • Lateral geniculate body and
    • Pulvinar of the thalamus
  • Is part of the sub and retrolenticular component of the internal capsule.
  • Course
    • Forms part of the posterior thalamic peduncle;
    • Passes under the lentiform nucleus as fibres of the sublenticular part of the internal capsule,
    • Above the stria terminalis and the tail of the caudate nucleus; and
    • Joins the sagittal stratum that forms the lateral ventricular wall.
  • Relation
    • Located within middle and superior temporal gyri, and always above the inferior temporal sulcus
    • The mean distance between the cortical surface of the middle temporal gyrus and the lateral edge of the optic radiation was 21 mm
    • Forms part of the roof and lateral wall of the temporal horn
  • Terminate at the calcarine cortex (Brodmann area 17) within the superior and inferior lips of the calcarine fissure
  • Average length was 95mm
  • 3 parts
      • Anterior bundle (meyer loop)
      • Course
        • Follows an anterolateral direction along the roof of the temporal horn, lateral to the amygdala and perpendicular to the anterior commissure.
        • Anterior to the temporal horn, the fibres shift backward, forming the Meyer loop, assuming a posterolateral course, hence becoming lateral to the temporal horn and to the atrium, and ending along the inferior lip of the calcarine fissure
        • Extends up to the tip of the temporal horn
          • Of note:
            • Amygdala forms the anterior wall of the temporal horn
            • Hippocampus forms the floor of the temporal horn
        • Most vulnerable part of the optic radiation when approaching the temporal horn and the temporomedial region.
          • Damage results in superior homonymous quadrantanopic visual field deficits,
            • Occurs in 50% to 90% of cases after anterior temporal lobectomies
              •  
      UncFasc M매•『•• Loob
      FIGURE 2. Images in 3 (A) and 2 (B) dimensions. Infemlateral view of the right hemisphere. The lenticular nucleus, anterior commissure (AntCom), occi- pitofrontal, superior longitudinal (SupLongFasc), and uncinare fascicles have been partially removed to expose the corona radiate (CORA), internal capsule, optic radiation (OptRnd), and optic tract (OptTr). Antl„imb, anterior limb of the internal capsule; COFO, column or pillar of the fornix; CoSnFi, cortical srriatal fibers; MaBo, mammillary body; put, putamen. Meyer'S optRad FIGURE 3. Images in 3 (A) and 2 (B) dimensions. View Of the roof Of the left temporal horn, where the ependyma, tapetum, and choroid plexus have been partially removed to disclose the origin and trajectory of the bundles of optic radiation (OptRad). The anterior bundle (AntB; red), central bundle (CenB; yellow), and posterior bundle (PostB; green) are shown. LatGeBo, lateral geniculate body; MeGeBod, medial geniculate body; OptTr, optic tract; Pulv, pulvinar of thalamus; UncFasc, uncinate fasciculus.
      View of the roof of the left temporal horn, where the ependyma, tapetum, and choroid plexus have been partially removed to disclose the origin and trajectory of the bundles of optic radiation (OptRad). The anterior bundle (AntB; red), central bundle (CenB; yellow), and posterior bundle (PostB; green) are shown. LatGeBo, lateral geniculate body; MeGeBod, medial geniculate body; OptTr, optic tract; Pulv, pulvinar of thalamus; UncFasc, uncinate fasciculus.
      • Measurements
          • Point A
          Point B
          Distance (mm)
          Ambient gyrus (uncus)
          Meyer loop
          22
          Temporal pole
          anterior edge of the Meyer loop
          28.4 (20-33)
          Anterior border of Meyer loop
          • Meyer loop is anterior to temporal horn
          • At this level, the anterior commissure fibres (of the occipital extension) were found to be intermingled with the optic radiation fibres.
          Temporal horn
          4.5 (2-7)
          Limen insulae
          Meyer loop (anterior bundle)
          10.7 (7-13)
          Anterior edge of Meyer loop
          Lateral geniculate body
          21 (18-28)
          Tep Amygdala ead Anta • —L,atGeBo post FIGURE I. Inferior Of the optic radiation with the measurements that were done. A-B, the distance between temporalpole (TePo) and the anterior edge of the Meyer loop. C-D, distance between the anterior wall of temporal horn and the anterior edge Of the Meyer loop. E-F, distance between the anterior edge Of the Meyer loop and the lateral geniculate body (LatGeBo). G-H, distance between the lateral geniculate body and the lateral edge of the optic radiation. I-J, distance between the cortical surface ofthe middle temporalgyrus and lateral edge Of the optic radiation. K-L length Of the optic radiation. AntB, anterior bundle; Atr, atrium of lateral ventricle; CenB, central bundle; HippoHead, head of the hippocampus; PostB, posterior bundle.
          Inferior view of the optic radiation with the measurements that were done. A-B, the distance between temporal pole (TePo) and the anterior edge of the Meyer loop. C-D, distance between the anterior wall of temporal horn and the anterior edge of the Meyer loop. E-F, distance between the anterior edge of the Meyer loop and the lateral geniculate body (LatGeBo). G-H, distance between the lateral geniculate body and lateral edge of the optic radiation. I-J, distance between the cortical surface of the middle temporal gyrus and lateral edge of the optic radiation. K-L, length of the optic radiation. AntB, anterior bundle; Atr, atrium of lateral ventricle; CenB, central bundle; HippoHead, head of the hippocampus; PostB, posterior bundle.
      Central bundle
      • Course:
        • Lateral direction crossing superiorly the roof of the temporal horn and then turns sharply, following a posterior course lateral to the atrium and to the occipital horn, passing above and through the inferior longitudinal fasciculus, and ending at the lateral aspect of the occipital pole.
      • Relations
        • Anterior third of central bundle covers the auditory radiation,
        • Medially: Tapetum (Medial to tapetum is the ependyma of ventricle)
      • Measurements
        • Lateral geniculate body ↔ the central bundle: 17.4 mm
      STG MTG Sup. Temp. Sulcus Inf. Temp. Sulcus
      The anterior bundle (red), central bundle (yellow), and posterior bundle (green). CaF, calcarine fissure; Inf. Temp. Sulcus, inferior temporal sulcus; ITG, inferior temporal gyrus; MTG, middle temporal gyrus; STG, superior temporal gyrus; Sup. Temp. Sulcus, superior temporal sulcus; TeHo, temporal horn
      Posterior bundle (baum's loop)
      • Course: posteriorly, forming the lateral wall and part of the roof of the atrium and occipital horn, ending along the superior lip of the calcarine fissure.

Visual cortex

• Primary visual cortex - Calcarine sulcus • Secondary/ Tertiary visual cortex ceoua\ CENTRAL so\cus LOBULE CUNEUS fissure IST LINGUAL G YR US c, Infr Cingu CINGULATE GY corpus call osum s HIPPOCAMPAL G Y R Us i FUSIFOR YRUs— sulcus Tertiary visual cortex (area 19), V3 and V5 Secondary visual cortex (area 18), V2 Calcarine sulcus Primary visual cortex (Brodmann's area 17), VI
vtr,
 

Striate cortex

  • Visual processing involves signal relay from the retina via the lateral geniculate nucleus to the striate cortex (area V1/primary visual cortex/calcarine cortex/Brodmann area 17).
  • Has strong retinotopic localisation, such that striate occipital lesions cause deficits restricted to segments of the visual field.
  • Primary visual cortex (V1/Area 17)
    • Sup: Cuneus gyrus
    • Calcarine fissure
    • Inf: lingual gyrus
  • The band/line of Gennari
      • Myelinated fibres of optic radiation that enter the visual cortex on the layer 4
      • Gives the striated appearance of the visual cortex on myelin staining
      37. Visual Pathways Flashcards | Quizlet

Extra-striate cortex (Association cortexes)

  • Located in Brodmann areas 18/19 at occipital lobe
  • Organised more by process than by visual field location
    • Different areas of extrastriate cortex are involved in colour, motion perception, etc:
  • Defects
    • Deficits in certain aspects of vision:
      • Perception of motion, affecting the entire visual field.
  • Comprised of
    • V2
    • V3
      • Selective for orientation.
    • V4
    • V5 (MT: Middle temporal)
  • Function
    • Integrating visual information
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Location of optic radiation in relation to atrium and tapetum

  • The optic radiations does not cover the superior 1/3 of the atrium
  • The optic radiations overlies the tapetum of the corpus callosum
  • The tapetum also overlies the atrium of the lateral ventricles
  • Both the optic radiations and tapetum form the lateral wall of the atrium and occipital horn of the lateral ventricles
 
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General
  • Retina → Optic nerve → Optic chiasm → Optic Tract → Lateral geniculate body → optic radiation → Calcarine cortex
Retina
  • Rod/cone (photoreceptors) → Bipolar cells (primary sensory neurons) → ganglion cells (secondary sensory neurons)
  • Ganglion cell types
    • Classes XYW system
          • Cell type
          Function
          Response type
          Transmission rate
          Cell body
          X cells
          80% analysis of detail and colour
          Tonic response to: pretectum, LGN
          Slow
          Largest
          Y cells
          Motion detection
          Phasic response to: LGN, Superior colliculus
          Rapid
          W cells
          Project to brainstem
          Tonic and phasic response to superior colliculus, pretectum
          Very slow
          Smallest
        • 3 locations that the cells response to
          • Pretectum: pupillary reaction (light reflex)
          • LGN: conscious vision-cortical visual processing
          • Superior colliculus: eye movement
  • Receptive fields
Optic nerve
  • Made up of: Ganglion cell axons + Glia cells
Lateral geniculate body
  • Most fibres from optic tract reach LGB some end up in
    • Pulvinar
    • Pretectal nucleus
    • Superior colliculi
  • Has 6 layers
      • Magnocellular (large cell) layers:
        • Layers 1,2
        • Movements and location
      • Parvocellular (small cell) layers:
        • Layers 3-6
        • Colour and detailed forms
      • Contralateral nasal hemiretina project to layers 1,4,6
      • Ipsilateral nasal hemiretina project to layers 2,3,5
      • Do not overlap
      • Exit the LGN as optic radiations
        • Magnocellular pathway (ventral)
        • Parvocellular pathway (dorsal)
      • Here they still contain the on and off center and surround visual processing like the bipolar cells
      Left eye Temporal hemiretina Left optic tract 2 3 4 5 6 Magnocellular pathway hemiretina Optic chiasm Right eye 2 3 4 5 6 Temporal hemiretina Right optic tract Lateral geniculate nucleus Parvocellular pathway Ventral Dorsal Primary visual cortex
      LGN - showing six cellular layers. Magnocellular (green) and Parvocellular (brown). layers are tiny neurons ventral to each layer.
      LGN - showing six cellular layers. Magnocellular (green) and Parvocellular (brown). Koniocellular (pink) layers are tiny neurons ventral to each layer.

Pathology

  • Diseases of the afferent visual system
    • Compressive and Infiltrative Optic Neuropathies
      • Compression: Classified by location
        • Intra-orbit
          • Thyroid eye disease
          • Optic nerve sheath meningioma
        • In optic canal
          • Meningioma in the optic canal
        • Intracranial
          • Sphenoid wing meningiomas
          • Pituitary adenomas
          • Opthalmic artery aneurysms
    • Causes slow progressive vision loss
Visual field defects
macula optic nerve pituitary knee of Wilbrand optic chiasm optic tract lateral genicu- late body (LGB) Meyer's loop optic radiation left occipital (visual) cortex * Macular sparing may occur with some partial injuries to the optic radiation or with a PCA stroke in a patient whose occipital pole receives anomalous blood supply from the MCA. Patient's View RIGHT EYE COMMENT normal "blind spot" lesion Of optic nerve anterior to optic chiasm: monocular blindness, right eye lesion of optic nerve & knee of Wilbrand: junctional scotoma (monocular blindness, right eye + contralateral (left) superior temporal quadrantanopsia) lesion of optic chiasm: bitemporal hemianopsia lesion of optic tract or optic radiation: homonymous hemianopsia with macular spJjttLng of left visual field lesion of Meyer's loop: homonymous left superior quadrantanopsia with macular sparing* of left visual field partial lesion of optic radiation or visual cortex: homonymous hemianopsia with macular spar-ingl of left visual field
Junctional scotoma Bitemporal defect Incongruous right homonymous hemianopia Incongruous homonymous superior quadrantanopia Hemichiasmal defect Central bitemporal hemianopia Left homonymous horizontal sectoranopia Right parietal lobe lesion
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Images

Spl Glopa Meyer-s loop CenB TapetumCS OptRad supLiöCaF DiBandBr AntCom FIGURE 4. Images in 3 (A) and 2 (B) dimensions. Lateral view. Optic radiation (OptRad) of the left hemisphere; the section of the superior longitudinal lus (SupLongFasc) allows exposure Of the central (CenB) and posterior bundles (PostB), which end at the lateral aspect of occipital pole and superior lip of the calcarinefissure, respectively. AntCom, anterior commissure; CalV, caudate nucleus; CORa, corona radiata; DiBandBr, diagonal band of Broca; GloPa, globus pallidus; IntCap, internal capsule. FIGURE 5. Images in 3 (A) and 2 (B) dimensions. Magnified view of the trajectory of 'be central and posterior bundles. The taperum constitutes the medial roof of the ventricular atrium. CenB, central bundle; OptRad, optic radiation; PostB, posterior bundle; SupLipCaF, superior lip of the calcarine fissure; SupLongFasc, superior longitudinal fasciculus; Spl, splenium Of the corpus callosum.
Magnified view of the trajectory of the central and posterior bundles. The tapetum constitutes the medial roof of the ventricular atrium. CenB, central bundle; OptRad, optic radiation; PostB, posterior bundle; SupLipCaF, superior lip of the calcarine fissure; SupLongFasc, superior longitudinal fasciculus; Spl, splenium of the corpus callosum.
FIGURE 2. Images in 3 (A) and 2 (B) dimensions. Infemlateral view of the right hemisphere. The lenticular nucleus, anterior commissure (AntCom), occi- pitofrontal, superior longitudinal (SupLongFasc), and uncinare fascicles have been partially removed to expose the corona radiate (CORA), internal capsule, optic radiation (OptRnd), and optic tract (OptTr). Antl„imb, anterior limb of the internal capsule; COFO, column or pillar of the fornix; CoSnFi, cortical srriatal fibers; MaBo, mammillary body; put, putamen. Meyer'S optRad FIGURE 3. Images in 3 (A) and 2 (B) dimensions. View Of the roof Of the left temporal horn, where the ependyma, tapetum, and choroid plexus have been partially removed to disclose the origin and trajectory of the bundles of optic radiation (OptRad). The anterior bundle (AntB; red), central bundle (CenB; yellow), and posterior bundle (PostB; green) are shown. LatGeBo, lateral geniculate body; MeGeBod, medial geniculate body; OptTr, optic tract; Pulv, pulvinar of thalamus; UncFasc, uncinate fasciculus.
Inferolateral view of the right hemisphere. The lenticular nucleus, anterior commissure (AntCom), occipitofrontal, superior longitudinal (SupLongFasc), and uncinate fascicles have been partially removed to expose the corona radiate (CoRa), internal capsule, optic radiation (OptRad), and optic tract (OptTr). AntLimb, anterior limb of the internal capsule; CoFo, column or pillar of the fornix; CoStrFi, cortical striatal fibers; MaBo, mammillary body; Put, putamen.
optRad Limon repo Inf. Temp. Sulcus FIGURE 6. Images in 3 (A) and 2 (B) dimensions. Lateral' view. The superior, middle temporal, angular, and occipital gyri were removed. Observe rhe optic radiation located deep to the superior and middle temporal gyri, above the inferior temporal sulcus. CS, central sulcus; Inf Temp. Sulcus, Inferior temporal sulcus; inferior limiting sulcus; IT G, inferior temporal gyrus; MFG, middle frontal gyms; optic radiation; PostCG, Postcentral gyms; PreCG, precentral gyms; SPLob, superior parietal lobe; TePo, temporal pole. FIGURE 7. Images in 3 (A) and 2 (B) dimensions. Lateral view of left hemisphere. Parts of the superior longitudinal fasciculus (Sup LongFasc) were removed to expose the corona radiata and the sagittal stratum (SagStr). Occi- pitofrontal (OcFrFasc) and uncinate fasciculus (UncFasc) can be identified Passing along the basal portion Of the insular cortex. AntCom, anterior com- missure; CORa, corona radia'e; Glopa, globus pallidus.
Lateral view of left hemisphere. Parts of the superior longitudinal fasciculus (SupLongFasc) were removed to expose the corona radiata and the sagittal stratum (SagStr). Occipitofrontal (OcFrFasc) and uncinate fasciculus (UncFasc) can be identified passing along the basal portion of the insular cortex. AntCom, anterior commissure; CoRa, corona radiate; GloPa, globus pallidus.
Fasc XAntCom— FIGURE I O. Images in 3 (A) and 2 (B) dimensions. Anterolateral view of the left hemisphere. The occipitøfrontal and the uncinate and the putamen were removed m expose the anterior commissure. The diagonal band of Broca (DiBandBr) and its junction with rhe amygdala are inferior to the lateral aspect Of the anterior commissure (AntCom). CORI, corona radiata,• Glopa, globus pallidus; HippoHead, head Of the hippocampus; IntCap, internal capsule; SagStr, saginal stratum; SupLongFasc, superior longitudinal fasciculus.
Anterolateral view of the left hemisphere. The occipitofrontal and the uncinate fasciculi and the putamen were removed to expose the anterior commissure. The diagonal band of Broca (DiBandBr) and its junction with the amygdala are inferior to the lateral aspect of the anterior commissure (AntCom). CoRa, corona radiata; GloPa, globus pallidus; HippoHead, head of the hippocampus; IntCap, internal capsule; SagStr, sagittal stratum; SupLongFasc, superior longitudinal fasciculus.
OTO N
Optic radiation arising from the lateral geniculate body
Lateral view: Meyer's loop (ML), Amygdala (A), Hippocampus located in the floor of temporal horn
Lateral view: Meyer's loop (ML), Amygdala (A), Hippocampus located in the floor of temporal horn
After arising in the Lateral geniculate body (LGB), the optic radiation fibres pass between the inferior limiting sulcus (ILS) and tail of the caudate nucleus (CT) to cover the roof and lateral wall of the temporal horn (TH).
After arising in the Lateral geniculate body (LGB), the optic radiation fibres pass between the inferior limiting sulcus (ILS) and tail of the caudate nucleus (CT) to cover the roof and lateral wall of the temporal horn (TH).
Spl Glopa Meyer-s loop CenB TapetumCS OptRad supLiöCaF DiBandBr AntCom FIGURE 4. Images in 3 (A) and 2 (B) dimensions. Lateral view. Optic radiation (OptRad) of the left hemisphere; the section of the superior longitudinal lus (SupLongFasc) allows exposure Of the central (CenB) and posterior bundles (PostB), which end at the lateral aspect of occipital pole and superior lip of the calcarinefissure, respectively. AntCom, anterior commissure; CalV, caudate nucleus; CORa, corona radiata; DiBandBr, diagonal band of Broca; GloPa, globus pallidus; IntCap, internal capsule. FIGURE 5. Images in 3 (A) and 2 (B) dimensions. Magnified view of the trajectory of 'be central and posterior bundles. The taperum constitutes the medial roof of the ventricular atrium. CenB, central bundle; OptRad, optic radiation; PostB, posterior bundle; SupLipCaF, superior lip of the calcarine fissure; SupLongFasc, superior longitudinal fasciculus; Spl, splenium Of the corpus callosum.
Lateral view. Optic radiation (OptRad) of the left hemisphere; the section of the superior longitudinal fasciculus (SupLongFasc) allows exposure of the central (CenB) and posterior bundles (PostB), which end at the lateral aspect of occipital pole and superior lip of the calcarine fissure, respectively. AntCom, anterior commissure; CaN, caudate nucleus; CoRa, corona radiata; DiBandBr, diagonal band of Broca; GloPa, globus pallidus; IntCap, internal capsule.
optRad Limon repo Inf. Temp. Sulcus FIGURE 6. Images in 3 (A) and 2 (B) dimensions. Lateral' view. The superior, middle temporal, angular, and occipital gyri were removed. Observe rhe optic radiation located deep to the superior and middle temporal gyri, above the inferior temporal sulcus. CS, central sulcus; Inf Temp. Sulcus, Inferior temporal sulcus; inferior limiting sulcus; IT G, inferior temporal gyrus; MFG, middle frontal gyms; optic radiation; PostCG, Postcentral gyms; PreCG, precentral gyms; SPLob, superior parietal lobe; TePo, temporal pole. FIGURE 7. Images in 3 (A) and 2 (B) dimensions. Lateral view of left hemisphere. Parts of the superior longitudinal fasciculus (Sup LongFasc) were removed to expose the corona radiata and the sagittal stratum (SagStr). Occi- pitofrontal (OcFrFasc) and uncinate fasciculus (UncFasc) can be identified Passing along the basal portion Of the insular cortex. AntCom, anterior com- missure; CORa, corona radia'e; Glopa, globus pallidus.
Lateral view. The superior, middle temporal, angular, and occipital gyri were removed. Observe the optic radiation location deep to the superior and middle temporal gyri, above the inferior temporal sulcus. CS, central sulcus; Inf. Temp. Sulcus, inferior temporal sulcus; InfLimS, inferior limiting sulcus; ITG, inferior temporal gyrus; MFG, middle frontal gyrus; OptRad, optic radiation; PostCG, postcentral gyrus; PreCG, precentral gyrus; SPLob, superior parietal lobe; TePo, temporal pole.
A close-up of a human brain AI-generated content may be incorrect.
Magnified lateral view. The internal capsule was partially removed to expose the head and body of the caudate nucleus. The portion of the ventricular frontal horn anterior to the head of the caudate can be appreciated. AntCom, anterior commissure; CaN, caudate nucleus; CoRa, corona radiata; DiBandBr, diagonal band of Broca; GloPa, globus pallidus; IntCap, internal capsule; NuclAccumb, nucleus accumbens; OptRad, optic radiation; SepPel, septum pellucidum; SupLongFasc, superior longitudinal fasciculus.
Meyer's Ch —AntCom optic' OptRad LatG Precu InfLipCaF FIGURE 13. Images in 3 (A) and 2 (B) dimensions. Basal view of the neural visual pathways. The temporal gyrus has been removed bilaterally, preserving the optic radiations (OptRad). The temporal stem has been removed, exposing the Meyer loop and the trajectory of its fibers that reach the inferior lip of the calcarinefissure (InfZipCaF). In the left temporal horn, the ependyma has been removed, and the tapetum can be seen along the atrium. AntCom, anterior commissure; AntLimb, anterior limb of the internal capsule; LqtGeBo, lateral geniculate body; OpCh, optic chiasm; OptTr, optic tract; PreCu, precuneus; UncFasc, u n cinate fasciculus.
Basal view of the neural visual pathways. The temporal gyrus has been removed bilaterally, preserving the optic radiations (OptRad). The temporal stem has been removed, exposing the Meyer loop and the trajectory of its fibers that reach the inferior lip of the calcarine fissure (InfLipCaF). In the left temporal horn, the ependyma has been removed, and the tapetum can be seen along the atrium. AntCom, anterior commissure; AntLimb, anterior limb of the internal capsule; LatGeBo, lateral geniculate body; OpCh, optic chiasm; OptTr, optic tract; PreCu, precuneus; UncFasc, uncinate fasciculus.