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Paediatric Neuroanatomy

Hemispheres, Lobes & Gyri

Commisures.

= WM bundle connecting hemispheres.

  • Corpus Callosum
  • Anterior Commisure
  • Posterior Commisure
  • Habenular Commisure
  • Hippocampal Commisure

Frontal Lobe

Emotion
Motor = Posterior Part = Precentral Gyrus = Primary Motor Cortex.

Lateral surface

  • Superior Frontal Gyrus
  • Middle Frontal Gyrus
  • Inferior Frontal Gyrus
    • Broca's Area = Inferior LEFT Frontal Gyrus.
      • PRODUCTION
      • Pars Opercularis & Pars Triangularis

Inferior surface.

  • Gyrus Rectus ( Medial ). Adjacent to Olfactory bulbs
  • Medial Orbital Gyri
  • Lateral Orbital Gyri ( Lateral )

Temporal Lobe

Lateral Margin.

  • Superior Temporal Gyrus
  • Middle Temporal Gyrus
  • Inferior Temporal Gyrus
    Inferior Margin
  • Occipitotemporal Gyrus = Fusiform Gyrus
  • Parahippocampal Gyrus
    Other Parts
  • Amygdala = Anterior aspect of Temporal horn of Lateral Ventricle
  • Uncus = Medial projection of Temporal horn
  • Transverse Temporal Gyrus aka Heschl's Gyrus
    • Between Posterior Insula ==> Superior Temporal Gyrus.
    • Auditory Processing
    • Wernicke's Area = Posterior LEFT Superior Temporal Gyrus
      • RECEPTION

Connection between Wernicke's & Broca's : Arcuate Fasiculus.

Parietal Lobe

Superior Part
Inferior Part

  • Angular Gyrus
  • Supramarginal Gyrus

Occipital Lobe

Cuneus

  • Part behind the parieto-occipital fissure and the Calcarine fissure.
    Calcarine Fissure
  • Just off Midline & vaguely Ant-post.
  • lined with Primary Visual Cortex

Deep Strutures

Globi Palldi --> Hypothalami -->[Merge midline]-->Infundibular stalk.

Midline Structures

Corpus Callosum Parts: Rostrum, Genu, Body, Isthmus, Splenium. 'Homotopic' = connects the same part of the cerebral hemispheres together.
Contains white matter tracts.

  • 'Forceps Minor' => Genu = Frontal pole connectors.
  • 'Forceps Major' => Splenium = Occipital pole connectors.

Pineal Gland Directly above the Posterior Commisure.

Tectal Plate
Most posterior part of midbrain.
-2 Superior colliculi = Vision. -2 Inferior colliculi = Auditory.

Ventricles & CSF Spaces

'Cistern': Occurs when pia mater and arachnoid are not closely aligned.

  • Perimesencephalic Cisterns : around midbrain.
    • Crural Cisterns : anterolateral.
    • Ambient Cisterns : lateral.
    • Quadrigeminal: posterior.
  • Prepontine Cistern.
  • Cerebellopontine Angle Cistern.
  • Lateral Medullary Cisterns. ( Lateral to medulla )
  • Cisterna Magna ( below cerebellar vermis )

Myelination 1

White Matter Bundles

  • Commisural: Joins to opposite hemisphere.
  • Association: Joins within the same hemisphere.
  • Projection: Extend to deep grey, brainstem, cerebellum.

Is divided into:

  1. Juxacortical.
  2. Deep White Matter
    • Periventricular is a subset.

Unmyelinated White Matter

  • Very high water content (80%) thus,
  • T1: LOW, T2: HIGH

Myelinated White Matter

  • = Proteolipid 70% Lipid, 30% Protein thus,
  • T1: HIGH, T2: LOW.
  • The water content is still 70% though.

But Transition Phase

  • have lipid precursors thus HIGH T1,
  • but not yet hydrophobic thus high water and HIGH T2.
  • Thus, T1 shortening is seen about 3 months before decline in T2.

Myelination timetable.

Read Normal Myelination Atlas (here)[../papers/Myelination_Paed.pdf]

Term 2 mths 4 mths 6 mths 9 mths 12mths 18mths
Internal Capsule Spot in post PLIC Most PLIC PLIC +/- Angle Into ALIC Whole IC
Corpus Callosum Isthmus & Body Splenium +/- Genu Whole Genu
Cerebral Hemispheres +/- Optic Radiation Most occipital. Some Frontal J/C in Occiput J/C in Frontal T2 high in J/C Frontal.

J/C = Juxtacortical. Myelination correlates with development of function. Juxtacortical WM in the frontal lobe is still maturing up to 2yrs on T2 and microstructurally to adolescence. "U:\EBR\papers\Myelination_Paed.pdf"

Footnotes

  1. Choudri, Asim. Pediatric Neuroradiology: Clinical Practice Essentials. Thieme 2017. ↩