1 - Introduction to Functional Organisation of the CNS Flashcards
Can CT and MRI distinguish between grey and white matter?
Yes
Imaging type that can visualise only white matter
Diffusion weighted MRI
*Orientations of primate brain
BRAIN DIRECTIONS
Name for fissure between lobes of brain
Longitudinal fissure
Name for ridges of the cerebrum
Gyri/gyrus
Name for grooves in cerebrum
Sulci/sulcus
Organisation of the cerebral cortex
Four divisions (frontal, temporal, parietal, occipital. Not functionally very useful distinctions.
Brain areas based on cellular differences
Brodmann areas. Largely functionally significant
*Which kind of brain imaging produced this image?
PET scan
What determines the histological layered structure of the brain?
Different neuron morphologies
Proportion of brain’s neurons in the cerebellum
~70% of all neurons in brain
Basic role of the cerebellum
Compares what your body wishes to do (in terms of movement) with what the muscles are actually doing. Makes movement more smooth. Also learning motor function.
Location of basal ganglia
In telencephalon
Role of basal ganglia
Selects, initiates voluntary movements. Form loops with cortex (for execution)
What does damage of basal ganglia lead to?
Parkinson’s, Huntington’s diseases. Movement disorders.
Striatum
Caudate and putamen
Where in the brain are the thalami?
Diencephalon
Role of thalami
Sensory relay between body and cortex
Three different ways in which thalamic nuclei can project
- Relays sensory information to specific areas of cortex 2. Relays of non-sensory information from cortex and basal ganglia to specific areas of cortex 3. Project globally to cortex; arousal, sleep
Where in the brain is the hypothalamus?
Below thalamus, on the ventral surface of the brain (bottom part)
Gland hanging from the hypothalamus
Pituitary gland
Role of hypothalamus
Regulates homeostasis (temperature, blood volume and pressure, ion concentration, pH, O2 and glucose)
Role of brainstem 1 2 3 4
1) Facial muscles 2) Sensation from face, head 3) Cardiorespiratory control 4) Arousal, sleep/wake cycle
*Gross organisation of the spinal cord
Changes in spinal cord shape over length
Divided into cervical, thoracic, lumbar and sacral regions. Enlarged at lower cervical and lumbar regions (for innervation of limbs).
*Shape of spinal cord over length
Where does the spinal cord end?
~L1/L2 boundary
Organisation of spinal nerves
Each spinal segment gives rise to a pair of spinal nerves
How do spinal nerves leave the spinal cord?
Each formed by dorsal and ventral roots from the spinal cord, which fuse to form spinal nerve
Role of ventral root
Exclusively motor (control skeletal muscle)
Role of dorsal root
Exclusively sensory.
Location of dorsal root ganglia
Hidden between vertebrae
Role of dorsal root ganglia
Location of cell bodies of primary sensory afferent neurons
Organisation of neurons in dorsal root ganglia
Cell body location in DRG. Splits into two axons. One goes to periphery, innervates site. Other branch enters dorsal horn via dorsal root
Composition of most peripheral nerves
Mixed sensory and motor axons
Number of ventricles
Two lateral ventricles, one third, one fourth, cerebral aqueduct
Clinical importance of ventricles
Used to orientate the brain on an MRI, CT
What forms CSF?
Vascular choroid plexus. CSF is an ultrafiltrate of plasma.
Where is the choroid plexus?
Surface of ventricles
Where does CSF exit brain?
Fourth ventricle. Drains into the subarachnoid space
Layers of meninges
Dura (thickest, outermost) Arachnoid (fibrous, middle) Pia (thinnest, innermost)
Two extensions of meninges
Falx and tentorium
Falx
Extension of meninges into longitudinal fissure
Tentorium
Extension of meninges between cerebellum and occipital lobe
Significance of falx and tentorium
Fix brain in place. If there is swelling somewhere in the brain, the brain becomes compressed, has to squeeze through a hole in the middle of tentorium
