Topography of the Brain

Summary

  • Parts of the brain
    • Lobes
    • Sulcus and gyrus

Parts of the brain

  • Broadly, there are 4 main regions of note in the brain:
  1. Cerebral hemispheres (aka telencephalon, cerebrum )
    • Separated by longitudinal fissure
    • Each hemisphere contains a cavity called the lateral ventricles
    • There are multiple regions within the hemispheres (see ‘lobes of the brain’ below)
  2. Diencephalon
    • Surrounds the 3rd ventricle
    • Composed of:
      1. Epithalamus (pineal gland)
      2. Dorsal thalamus
      3. Hypothalamus
      4. Thalamus
  3. The brainstem
    • Lies within middle/posterior cranial fossae
    • Made up of 3 parts:
      • Midbrain (Mesencephalon)
        • Most rostral part of the brainstem
        • Between the middle/posterior cranial fossae
        • Contains cerebral aqueduct
      • Pons
        • Middle part of brainstem
        • Lies in posterior cranial fossa
        • Part of the 4th ventricle
      • Medulla oblongata
        • Caudal part of brainstem
        • Continuous with spinal cord
      • The main parts of the brain. Note that the forebrain includes both telencephalon (cerebrum) and diencephalon.
  4. Cerebellum
    • Below tentorium cerebri
    • 2 hemispheres joined by the vermis
Lobes of the cerebral hemispheres
  • There are six main areas of the cerebrum to consider (FM SPOT):
    • Frontal lobe – responsible for planning and personality
    • Motor Cortex – movement
    • Sensory Cortex – sensations
    • Parietal lobe – spelling, calculations, perception
    • Occipital lobeVision
    • Temporal lobe – Memory, language
  • Connected by corpus callosum
    • This unites hemispheres via commissural fibres
    • Also have other commissures

      Parts of the brain and their functions (simplified)
  • The sulci and gyri are part of the cerebral cortex (i.e. the surface of the brain)
    • Sulcus – depressions
    • Gyrus – ridges

    • Certain fixed sulcus’/gyrus’ serve as landmarks of separations between lobes
      • Central sulcus separates parietal and frontal lobes
      • Pre-central gyrus – contains the primary motor cortex
      • Post-central gyrus –  contains the primary sensory cortex

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