BBS1004 - Summary
Faculty of Health Medicine and Life
Joséphine Misonne
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, 1. ORGANIZATION OF THE BRAIN
a. DIFFERENT PARTS OF THE BRAIN
FOREBRAIN
The prosencephalon in the seat of perceptions, conscious awareness, cognition, and voluntary actions.
All this depends on extensive interconnections with the sensory and motor neurons of the brainstem
and the spinal cord.
The most important structure in the forebrain is the cerebral cortex. Cortical neurons receive sensory
information, from perceptions of the outside world, and command voluntary movements.
Lateral ventricles = fluid-filled spaces within the cerebral hemispheres.
Third ventricle = the space at the centre of the diencephalon.
The walls of the telencephalic vesicles appear swollen due to the proliferation of neurons. These
neurons form two different types of gray matter in the telencephalon: the cerebral cortex and the basal
telencephalon.
The diencephalon differentiates into two structures: the thalamus and the hypothalamus. The
thalamus is nestled deep inside the forebrain.
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,MIDBRAIN
The mesencephalon serves as a conduit for information passing from the spinal cord to the forebrain
and vice versa. It contains neurons that contribute to sensory systems, the control of movements and
several other functions.
The midbrain contains axons descending from the cerebral cortex to the brain stem and the spinal cord.
Superior colliculus = receives direct input from the eye (also called optic tectum). It controls the eye
movements via synaptic connections with the motor neurons that innervate the eye muscles.
Inferior colliculus = receives sensory information from the ear. It serves as a relay station for auditory
information to the thalamus/
Cerebral aqueduct = CSF-filled space that connects the third ventricle with the fourth ventricle.
HINDBRAIN
The rhombencephalon is an important conduit for information passing from the forebrain to the spinal
cord, and vice versa. In addition, neurons of the hindbrain contribute to the processing of sensory
information, the control of voluntary movement, and regulation of the ANS.
Cerebellum = important movement control centre. It receives massive axonal inputs from the spinal
cord and the pons.
Spinal cord = provide information about the body’s position in space.
Pons = provide inputs that relay information from the cerebral cortex, specifying the goals of intended
movements.
➔ The cerebellum compares these types of information and calculates the sequences of muscle
contractions that are required to achieve the movement goals.
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, b. THE OUTSIDE OF THE BRAIN
MENINGES
= cerebral membranes that separate the brain from the skull.
Duna mater = most outer layer, tough and flexible, surrounds brain and spinal cord.
Arachnoid membrane = interposed layer, spider web, around brain and spinal cord (except for
longitudinal fissure)
Subarachnoid space
Pia mater = thin layer with blood vessels, adheres to surface of the brain into the fissures.
CEREBRAL HEMISPHERES / CORTEX
The brain has a convoluted surface to increase the surface/volume ratio and to increase the number of
cells. It represents 80% of the total brain weight.
Gyri = bumps, coils, twists
Sulci = grooves
Fissures = deep grooves
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