Development of Brain Diagrams with Explanation

Development of the Brain

Diagram overview:

Lateral view of the developing brain. The brain from cephalic to caudal becomes C shaped. The neural tube, which is straight in the beginning, also takes a C- shape, especially the forebrain (cerebral hemisphere and basal ganglia), whereas the rest remains almost straight.

Anterior View of the Developing Brain and Ventricles

Diagram overview:

• Anterior view of the developing brain and ventricles
• Forebrain/ Prosencephalon
  • Telencephalon
    • Cerebral hemispheres
    • Basal ganglia
    • Ventricles – First and second (lateral)
  • Diencephalon
    • Thalami
    • Third ventricle (midline)
• Midbrain /Mesencephalon – Cerebral aqueduct of Sylvius (midline)
• Hindbrain/Rhombencephalon
  • Metencephalon – develops into:
    • Pons
    • Cerebellum
  • Myelencephalon – Develops into Medulla oblongata
  • Fourth ventricle – Diamond shaped
• Medulla oblongata continues downwards as the spinal cord.
• The fourth ventricle continues downwards into the spinal cord as the central canal.

CSF 

• The CSF in the ventricles is formed by the choroid plexus.
• Most of the CSF is formed in the lateral ventricles as they are the largest ventricles.
• Choroid plexus is present at two locations: Rostral / Anterior, Caudal / Posterior

Cranial Nerves 

• There are 12 pairs of cranial nerves.
• CN I – Smell pathway – arises from Telencephalon
• CN II – Visual pathway – arises from Diencephalon
• CN III to XII – Arise from the brainstem.
• CN VIII – Vestibulocochlear nerve – hearing and balance - arises from the Ponto-medullary junction
• Cranial nerves I, II and VIII are pure sensory nerves.

Parts of the Adult Brain

Ventricles in the Adult Brain

Derivatives of the brain

CSF Drainage

Aqueduct Stenosis - It is blockage at Sylvius Aqueduct

• Blockage of flow of CSF leads to development of hydrocephalus.
• Lead to internal hydrocephalus
• Makes 3rd and lateral ventricles dilate and forebrain flatting
• There are four rounded swellings present on the tectum called Corpora quadrigemina:
  • Superior colliculi (2)
  • Inferior colliculi (2)
• During the development of the metencephalon, pons develop earlier than cerebellum.
• The developing cerebellum is connected to the brainstem (midbrain, pons and medulla) with the help of 3 cerebellar peduncles carrying axons:
  • Superior – Connected to midbrain
  • Middle – Connected to pons
  • Inferior – Connected to medulla
• The fourth ventricle sandwiched between anteriorly brain stem and cerebellum posteriorly mainly

Sagittal View

Diagram overview:

• The brain becomes c-shaped at the thalamus axis region. Forms 1st commisure anteriorly
• Commisure connects left and right brain
• 2nd commisure develop fornix
• 3rd commisure forms corpus collasum.
• Fornix is the output tract of the hippocampus which is related to short-term memory. It is the second commissure to develop.
• Corpus callosum is the third commissure to develop. It connects the cerebral hemispheres with each other.
• The thalamus appears as the axis on which other structures are taking the C-shape.
  • The cerebral hemispheres take the C shape and form lobes
    • Frontal, Occipital and Temporal.
  •  The temporal lobes are connected to each other by commissural fibres running in the corpus callosum, which itself becomes C-shaped.
  • The fornix also becomes C-shaped as it develops, connecting both parts of the hippocampus.
  • The hippocampus migrates inferiorly as the brain is developing. Therefore, it is found in the temporal lobe in the adult brain.
  • The choroid plexus, which is superior to the thalamus initially, grows posteriorly and then inferior to the thalamus.

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