UNSW Embryology

Central Nervous System - 3D Model Movie

© Dr Mark Hill (2008)

Acknowledgements

Central Nervous System (Stage 22)

 

Large CNS movie in new window	Colour Coding Telencephalon Diencephalon Mesencephalon Metencephalon Medulla (Myelencephalon) Spinal cord
	Other Models: | Central Nervous System | Cardiovasular | Gastrointestinal Tract | Urogenital | Skeletal

Description

Carnegie Stage 22 embryo (27mm Human embryo, approximate day 56)

Central Nervous System

During Week 5, as the neural tube continues to enlarge, the prosencephalon and rhombencephalon subdivide, while the mesencephalon expands. This gives rise to five secondary brain vesicles:

• From the Prosencephalon:
• Telencephlon – forms the cerebral hemispheres
• Diencephlon – forms the thalamus and hypothalamus

• Mesencephlon (doesn’t subdivide, expands) – forms the tectum and tegmentum

• From the Rhombencephlon:
• Metencephlon – forms the pons and the cerebellum
• Myelencephlon – forms the medulla oblongata

In each of these areas, the central canal running through the CNS enlarges and forms the ventricular system within the adult brain.

As the tube grows in diameter, it also bends due to the rapid proliferation and ventral folding of the embryo. The resulting flexures that occur in the brain are called primary brain flexures. Three flexures occur:

• The cervical flexure occurs between the brain and the spinal cord.
• The cephalic flexure pushes the mesencephalon upwards
• The pontine flexure occurs in the opposite direction from the other two; it generates the 4th ventricle

(More? Carnegie Stage 22 Neural Notes | Neural Notes)

Comments

This page is part of the UNSW Medical degree Independent Learning Project (ILP) prepared by Aashish Kumar (2006).

Please email Dr Mark Hill if you wish to make a comment about this current project.

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