Pixelated Brain: Module 8, Section 1 - The concept of functional components

MODULE 14 - SECTION 1 - THE DIENCEPHALON - HOW IT DEVELOPED
and
WHAT IT LOOKS LIKE

This section is a review of material that has been covered in earlier modules, so you can skip it if you think you are familiar with the subject

EARLY DEVELOPMENT of the BRAIN

Within the cranial cavity, the more caudal part of the tube develops into the medulla, pons and midbrain. Collectively these regions are known as the brain stem. The most rostral division of the neural tube, the forebrain, develops into the diencephalon and telencephalon (or cerebral hemisphere).

The color code used in this view will be used in the figures that follow, which trace the development of the brain.

     Cerebral Hemisphere      orange
     Diencephalon                    olive green
     Midbrain                           blue
     Pons (and Cerebellum)    purple
     Medulla                             yellow

THE CEREBELLAR PEDUNCLES

The enlarging cerebellum lies dorsal to the brainstem, but remains anchored to it by the three cerebellar peduncles.

SCHEMATIC FRONTAL SECTION
through the
INTERNAL CAPSULE

The diencephalon is surrounded, both dorsally and laterally, by the expanding cerebral hemisphere.

HOW to EXPOSE the THALAMUS - 2

This section shows the brain before such a cut.

THE THALAMUS EXPOSED - 2

MODULE 14 - SECTION 1 - THE DIENCEPHALON - HOW IT DEVELOPED and WHAT IT LOOKS LIKE This section is a review of material that has been covered in earlier modules, so you can skip it if you think you are familiar with the subject
	THE THREE PRIMARY VESICLES Recall that the brain starts out as a simple tube-like structure.
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	EARLY DEVELOPMENT of the BRAIN Within the cranial cavity, the more caudal part of the tube develops into the medulla, pons and midbrain. Collectively these regions are known as the brain stem. The most rostral division of the neural tube, the forebrain, develops into the diencephalon and telencephalon (or cerebral hemisphere). The color code used in this view will be used in the figures that follow, which trace the development of the brain. Cerebral Hemisphere orange Diencephalon olive green Midbrain blue Pons (and Cerebellum) purple Medulla yellow
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	DIVISIONS of the BRAINSTEM These regions are complex and may be subdivided into several components.
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	THE EXPANDING HEMISPHERE In this module we will start by considering the diencephalon as a whole, but then focus on the dorsal thalamus which - from this point on - we will refer to simply as the thalamus. Views such as the previous one above would suggest that we ought to be able to see the diencephalon "from above". But, because of the way in which the hemispheres expand to cover the more caudal part of the brain the diencephalon is hidden from view both dorsally and laterally.
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	THE CEREBELLAR PEDUNCLES The enlarging cerebellum lies dorsal to the brainstem, but remains anchored to it by the three cerebellar peduncles.
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	SCHEMATIC FRONTAL SECTION through the INTERNAL CAPSULE The diencephalon is surrounded, both dorsally and laterally, by the expanding cerebral hemisphere.
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	ATLAS VIEW - FRONTAL SLIDE 30 This atlas view, and the two that follow, simply relates the diencephalon (thalamus) to surrounding structures.
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	ATLAS VIEW - HORIZONTAL SLIDE 30 This atlas view simply relate the diencephalon (thalamus) to surrounding structures.
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	ATLAS VIEW - SAGITTAL SLIDE 18 This atlas view simply relates the diencephalon (thalamus) to surrounding structures.
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	A BASAL VIEW of the BRAIN Only a very limited part of this diencephalon - the hypothalamus - can actually be viewed without removing brain tissue. The surface of the hypothalamus is colored olive-green in the view, but only one landmark (the mammillary body) is labeled.
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	HOW to EXPOSE the THALAMUS - 1 If we had the luxury of working with real brains, we would expose the dorsal surface of the thalamus by cutting away the overlying hemisphere. In conceptual terms, we would make cut #1 as shown on the left on both sides and lift off the hemispheres.
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	HOW to EXPOSE the THALAMUS - 2 This section shows the brain before such a cut.
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	HOW to EXPOSE the THALAMUS - 3 This section shows the brain after the cut.
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	THE THALAMUS EXPOSED - 1
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	THE THALAMUS EXPOSED - 2
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