CNS overview Flashcards
What does the CNS consist of?
Brain and spinal cord
CNS of domestic species…..
Is entirely contained within the skull (brain) and vertebral column (spinal cord) and surrounded by 3 protective membranes called Meninges.
What is the role of the CNS
- to receive sensory info from the peripheral nervous system and then send motor info out
What are the broad regions of the brain?
- Cerebrum
- Diencephalon
- Brain stem: most cranial nerves arise, includes pons and medulla oblongata
- Cerebellum: maintaining balance and coordination of movement.
Cerebellum
- Behind the cerebrum
- “little brain”
- two lateral cerebellar hemispheres
- compares what you intended to do with what actually happened: organises and refines motor activity
- Vital for balance and coordination
- connected to brain stem by 3 PEDUNCLES of white matter on either side
- WM branches to look like a tree, grey = highly folded cortex on outside
Diencephalon
- consists of thalamus and hypothalamus
2. Diencephalon and cerebrum = forebrain
What is the first part of the brain stem?
Midbrain
What makes up grey and white
- Grey - nerve cell bodies, dendrites and synapses.
2. white matter = axons of CNS nerves
What are glial cells, nuclei and tracts
- GC = supporting cells in the CNS
- Clusters of cell bodies in the CNS
- Bundles of axons in the CNS
What is decussation?
where info from/ output to the right side of the body is handled by the left side of the brain.
This crossing over is called decussation
“The tracts decussate”
Where is white and grey matter arranged in the brain and spinal cord
- Spinal cord: WM outside, grey in
2. Brain: WM inside, GM outside forming cerebral cortex
What is the difference between the cerebrum adn cerebral cortex
- Cortex = just outside
2. cerebrum = whoel thing
What is the basal nuclei
- grey matter within the white matter of the brain.
- create stripey appearance called corpus striatum
- really important for planning and executing movments
What is the part of the brain that allows the RHS and LHS to coordinate with one another
- Corpus Callosum
- white matter
- means that if learn something on RHS cna do on LHS
Brain surface anatomy of cerebrum and cerebellum
Cerebrum:
1. ridges = GYRI (gyrus)
2. Furrows = SULCI (sulcus)
3. Cerebral hemispheres separated by longitudinal fissure
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Cerebrum separated from cerebellum by a transverse fissure
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Cerebellum
- folds = folia
- ——————–
How can the brain be divided up by
- anatomically
2. Functionally
Where is smell detected? what is the “nose brain”?
- Rhinencephalon = nose brain
- Ventral aspect
- Olfactory bulb = vert rostral aspect
- Piriform lobe = where most smell is processed
- Size reflects importance of olfaction to that species
- It communicates with centres to affect emotion (memory) behaviour and communication
What are spaces in the brain called and what for
- ventricles
- CNS is bathed in cerebrospinal fluid inside and out
- V produce and allow CSF to circulate around these interconnected V
What are the distinct areas in the brain?
For these functions:
- front = motor
- behind motor = somatosensory
- back = visual
- bottom = olfactory
- side = smell
What is the associated cortex
- much of the cortex is termed this
2. it integrates experiences with memories adn emotions
What is the limbic system
- series of tracts and nuclei which are key to emotion learning and memory
What is the thalamus
realy point for all sensory info coming into the brain, except olfactory input. Also involved in sleep and wakefulness
What is the hypothalamus
Connects the endocrine and nervous systems, and also has important roles in behaviour as it forms part of the limbic syste,
What is the brain stem comprised of
- midbrain, pons, medulla oblongata
- contains key control centres fr CV, RESP, GI
- contains the nuclei for most of the cranial nerves
- midbrain includes the TECTUM which is involved in orientating the head and body in response to sights and sounds (birds)
Species difference
- Degree of folding of cerebral cortex varies depending on their intelligence and how much space available
- Size and degree of dev of regions varies depending on importance of the functions of a given region
What does size of limbic system govern
- Larger limbic = species driven by instincts, less control over emotions and behaviours
What are the anatomical lobes of the cerebrum?
frontal lobe, parietal lobe, occipital lobe, temporal lobe (sides)
What are the folds of the cerebellar cortex called?
FOLIA
Which area is involved in emotion, memory adn learning A cerebellum B Limbic C Pons D Ventricles and say what the others are involved
ANSWER = B: limbic Cerebellum = coordination Pons = brain stem Ventricles = spaces in brain
How can we attempt to localise areas of damage?
- CNS contains groups of neurons in different regions, which are associated with specific functions
- injury or illness will cause different clinical signs depending on which region is affected,
- hence we can attempt to localise the area of damage by analysing the clinical signs an animal presents with
Cerebrum
- heavily folded
- divided into left and right cerebral hemisphere which is separated by a longitudinal fissure
- arises from the embryonic prosenceph
What are clusters of cell bodies within the CNS called and what is the PNS equivalent?
- Nuclei
2. CNS equivalent of the ganglia of PNS
Why is white matter white?
presence of fat in the myelin around the axons.
How is white matter organised?
What is the PNS equivalent?
bunches of axons which are called tracts (the CNS equivalent of anatomical nerves in the PNS), which connect different CNS regions
What are 2 main gyrus and sulcus?
- Cruciate sulcus
Forms a cross with the longitudinal fissure - Sylvan gyrus on lateral aspect of each hemisphere
How can the cerebral hemisphere be broadly divided anatomically?
- lobes according to which bones of the skull sit outside these areas
- Frontal, parietal, temporal, occipital
