Uppslagsverket

B

Brain

Encephalon

The brain (encephalon) is the part of the central nervous system enclosed in the cavity of the skull (cranium). In an adult, the brain is 16-17 cm long, approx. 12 cm high, approx. 12 cm wide and weighing about 1400 grams.

In the living human being at body temperature 37 degrees C., the brain tissue is liquid like a porridge. Since the brain is largely made up of fat, it solidifies when the body temperature drops. The brains depicted in the dissection section have been embalmed (fixed) and solidified further before being removed from the skull. The yellowish color is an effect of the embalming agent.

The brain consists of 3 main parts:
1/ Large brain (cerebrum).
2/ Cerebellum attached like a backpack to the back of the brain stem
3/ The brainstem (truncus encephali) which is the direct continuation of the spinal cord up into the head

The cerebrum is angled forward-downward almost 90 degrees relative to the brainstem, parts of which are located more or less on a straight line one after another.

The BRAIN is the body's most intricate organ. It is the one that gives us our personality and our emotions and is responsible for our consciousness, for our self-experience, for our perception of time and for our memory functions.
A normally functioning and reasonably fit brain is therefore the very basic prerequisite for humans to be able to move around in this life in an acceptable way.

The above classification is based on ancient dissection practice. A brain can most easily be divided into three parts. A narrower longitudinal piston-like middle section: the brainstem. At the front, the brainstem grows completely into an anterior larger rounded lump that with a simple incision can be cut off from the brainstem. The cerebrum, the cerebrum, is released. At the back of the brain stem is a smaller rounded solid-grown lump, which can also be detached from the brain stem with a simple incision. The cerebellum, the cerebellum, is released. And there it is, the brain, cut into its three main parts: the big brain, the small brain and the brain stem!

The brain's fetal development shows that at an early stage, the brain stem continues forward and forms a final part called the forebrain. The forebrain swells up and pushes out two buds, one to the right and one to the left. The forebrain midbrain is now called the midbrain and the buds are called endbrain buds, telencephalon buds or telencephalon vesicles. The telencephalon vesicles then start an extraordinarily strong and rapid growth. Read more about it here. Soon from the sides they cover practically all other parts of the brain. The telencephalon vesicles grow together across the midline and the cerebral cortex is formed. In addition, each telencephalon bladder grows together with the mid-aligned midbrain.

This development and the names presented have led to some confusion of names. It is now not uncommon to equate the "big brain", cerebrum and telencephalon. As a result, in some contexts, the midbrain (diencephalon) is considered the "big brain" and in others the "big brain" consists only of the fully developed telencephalon hemispheres!
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