Introduction to Functional Organisation of the CNS Flashcards
What makes up the CNS?
Brain
Spinal cord
Retina
What makes up the PNS?
Nerves
Ganglia
Where does the long axis of the CNS bend?
Cephalic flexure
What is the basic structure of the brain?
Cerebrum Cerebellum Brain stem Spinal cord Thalamus Hypothalamus Basal ganglia Limbic system
How many nuclei make up the basal ganglia?
5
What do the basal ganglia do?
Control motion and movement
What does the limbic system do?
Regulate emotion
What is grey matter?
Cell bodies of CNS
Where is grey matter in the brain?
Edge of cerebrum
How thick is grey matter in the brain?
0.5 cm
What is white matter?
Axons
What are axons?
Long processes from neurons
What is myelin?
Insulating sheath around axons to allow transmission of information over long distances rapidly
What is a T1 MRI image similar to?
Anatomical picture - white matter is white
What is the cerebrum divided into?
Two cerebral hemispheres
What divides the two cerebral hemispheres?
Longitudinal fissure
What is a ridge called?
Gyrus; pl: gyri
What is a groove called?
Sulcus; pl: sulci
What is the cerebrum responsible for?
Thing that makes us, us Language Emotions Self-awareness Behaviour
What are the four lobes of the cerebral cortex?
Frontal
Parietal
Temporal
Occipital
How are the four lobes divided?
Broadly separated by specific structural locations
What is the functional significance of the cerebral lobes?
Limited
Have broad functional differences - not specific
What does the frontal lobe broadly control?
Motor control
What does the parietal lobe broadly control?
Sensory control
What divides the frontal and parietal lobes?
Central sulcus
Where is the precentral gyrus?
In frontal lobe anterior to central sulcus
Where is the postcentral gyrus?
In parietal lobe posterior to central sulcus
What are Brodmann areas based on?
Cellular differences
Do Brodmann areas have any significance?
Yes, they have some significance
Most advanced method of labelling brain
What do PET scans identify?
Areas that are metabolically active with certain stimuli
Which lobe is active when hearing words?
Temporal lobe
Which lobe is active when seeing words?
Occipital lobe
Which lobes are active when speaking words?
Frontal and parietal lobes
What does the cerebellum do?
Compares what you want to do with what you are doing
Refines motor program
How can you test cerebellar function?
Touch nose with finger
If there’s a problem, person can’t touch nose because muscle movements aren’t corrected
What proportion of the neurons of the brain does the cerebellum have?
Half
What are the basal ganglia involved in?
Motor control
What do the basal ganglia do?
Select and initiate voluntary movement
Which part of the brain do the basal ganglia connect to and work with?
Cortex
What are two diseases involving basal ganglia?
Parkinson’s disease
Huntington’s disease
What are the five nuclei of the basal ganglia?
Caudate Putamen Globus pallidus Subthalamic nuclei Substantia nigra
What makes up the striatum?
Caudate
Putamen
Where are the basal ganglia located?
Close to midline
Where is the substantia nigra located?
Brain stem
Where is the thalamus?
In diencephalon
Where is the diencephalon?
A wall in the middle of the brain
What is the thalamus responsible for?
Sensory relay to cortex
What type of input is sensory input?
Afferent
What is the thalamus made up of?
Many nuclei
What is the broad role of thalamic nuclei?
Integrate info
What three ways do thalamic nuclei project?
Relay sensory information Relay non-sensory information from cortex and basal ganglia to specific areas Project globally to cortex - Controls arousal and sleep - Secondary role
Where is the hypothalamus?
Floor of diencephalon
In middle of brain near midline
What does the hypothalamus do?
Regulate homeostasis
What does the hypothalamus control?
Blood pressure and electrolyte levels Temperature Reproduction Energy metabolism Stress responses
What does the brain stem control?
Unconscious survival functions
- HR
- Breathing
- Complex reflexes
- Sneezing
- Coughing
What are cranial nerves?
Sensory and motor control to face and deeper structures
What part of the brain does the spinal cord continue on from?
Medulla in brain stem
What encloses the spinal cord?
Vertebrae
Where is the grey matter in the spinal cord?
Core
What is the spinal cord grey matter divided into?
Dorsal horns
Ventral horns
Intermediate zone
What is the spinal cord white matter divided into?
Dorsal columns
Ventral columns
Lateral columns
What information does the dorsal part of the spinal cord carry?
Sensory
What information does the ventral part of the spinal cord carry?
Motor
Where does the spinal cord end?
Around L1/L2
T/F: Each vertebra has corresponding spinal segment
True
How many nerves does each spinal segment give rise to?
Two
What is the cauda equina
Continues on from spinal cord
Individual strands of lumbar nerves
What forms a spinal nerve?
Dorsal root
Ventral root
What information does the dorsal root carry?
Sensory
What information does the ventral root carry?
Motor
What is in a dorsal root ganglion?
Neuronal somata
What type of nerve is a spinal nerve, in terms of information?
Mixed
What type of nerve are most peripheral nerves?
Mixed
What is a dermatome?
Region of body innervated by bilateral pair of dorsal root ganglia
What is the ventricular system?
Hollow centre of brain forming ventricles
What does the brain sit in?
Fluid
Where is CSF made?
Ventricles
What are the names of the ventricles?
Lateral ventricle - Largest - Close to midline Third ventricle - Near diencephalon Fourth ventricle - Near cerebellum
What makes CSF?
Vascular choroid plexus
What is CSF?
Ultrafiltrate plasma
No cells
Little protein
What is the choroid plexus?
Specialised epithelial cells
Where is the choroid plexus?
In ventricles
Where does CSF flow out of the ventricles?
At fourth ventricle
What is the role of CSF?
Nourishes brain
Protects brain from movement
What protects the brain?
Skull
Meninges
What are the three layers of meninges, from out to in?
Dura - Thickest Arachnoid - Fibrous Pia - Thinnest
Where is CSF absorbed into the venous system?
Arachnoid mater
What protects the ECF in the brain?
Blood brain barrier (BBB)
What is the BBB dependent on?
Tight junctions between endothelial cells in capillaries
What kind of transport is most common across the BBB?
Active transport
What happens when the BBB breaks down?
Neuron death
Immune cells of CNS enter body > wreak havoc