INSIDE THE HUMAN FOREBRAIN, Part 1

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• Wait 'til the tape fully loads before playing it!
• Scroll around, see where the pictures are!
• Gabby (the guy on the tape) will began talking about the THALAMUS. Check out the location of the thalamus package before you starting getting serious.
• You'll also find photos and drawings dealing with the basal nuclei and internal capsule.
• But the first two pictures will show you the uncomplicated plan of the forebrain, as seen in either simple vertebrates or the early human embryo. It wouldn't hurt to spend a couple of minutes looking at that stuff.
• Following the plan, you'll find a couple of optional pictures for a review, if you think you need it.

• This is a sagittal section, slightly off the midline, exposing the inner side of the right hemisphere and the cut surface of the corpus callosum.
• The T is the thalamus.
• Scroll for sections through a, b, c and c.
  [back to suggestions]

• T is the left thalamus
• 3 is the third ventricle, the space of the diencephalon.
  
• The big arrow points to the corpus callosum, spanning between the two cerebral hemispheres.
  
• The small arrow points to the anterior commissurea bridge between certain parts of the right and left basal nuclei.
  
• The "donkey ears" suspended from the corpus callosum are part of the fornix. (Check out the review picture, if necessary, Doc!).

• LF, longitudinal fissure
• cc, corpus callosum
• I and II, lateral ventricles
• III, third ventricle
• f, fornix
• mi, massa intermedia (thalamic adhesion)
• IC, internal capsule
• L, lenticular nuclues (a basal nucleus)

• CC, corpus callosum
• T, thalamus
• 3, third ventricle
• The arrowhead on the reader's left points to an optic tract.

[return to plane map]

• P is the pulvinar, the rear end of the thalamus. This section was cut a little cockeyed. The side on the reader's right is somewhat further posterior to the level on the left (with the P).
• The unlabeled mass seemingly levitating between the two pulvinars is the pineal body ; the latter is a part of the diencephalon known as the epithalamus). In the embryo and in primitive vertebrates, the epithalamus lies in the roof of the diencephalon -- where the pineal body could have served as a top-mounted third eye in creatures with a window in the dorsum of the skull e.g., the so-called living fossil, Sphenodon punctatum. The human pineal body is considered to be a vestigal third eye. (Gabby offers no opinion on the philosopher Descarte's contention that the pineal body represents the neuroanatomical seat of the soul.)
• U is the uncus; a basal nucleus called the amygdala lies in here.
• LGB, lateral geniculate body (or nucleus), a downward extension of the thalamus, is a relay station in the visual pathways.
• m, the medial geniculate body, also a downward extension of the thalamus, is a relay in the auditory pathways. Some authors classify the geniculate bodies as metathalamus.
• The corpus callosum, unlabeled here, is the large dark mass at the edge of the section, above the pineal body, towards 12 o'clock.
• [return to plane map]