NeuroAnatomy (P Felts) Flashcards
What is the CNS composed of?
The brain and spinal cord
What is the PNS composed of?
12 Cranial nerves and 31 pairs of spinal nerves (+ branches)
What are the first 3 swellings of the neural tube called during development?
Prosencephalon
Mesencephalon
Rhombencephalon
PRIMARY VESICLES
The Prosencephalon and Rhombencephalon divide into two further parts. What are these secondary vesicles named?
Prosencephalon = Telencephalon and Diencephalon
Rhombencephalon = Metencephalon and Mylencephalon
What does the mesencephalon become?
It remains as the mesencephalon between the diencephalon and metencephalon
What do each of the secondary vesicles give rise to in a mature brain?
Telencephalon - cerebral hemispheres Diencephalon - Thalamus and Hypothalamus Mesencephalon - Midbrain Metencephalon - Pons & Cerebellum Myelencephalon - Medulla Oblongata
What are the two main types of cell found in the CNS and what are their functions?
Neurons - communication via electrical impulses
Glial cells - “glue” the CNS together as there is no connective tissue for support
What are the 2 main types of neuron and what type of signals usually flow through each?
Multipolar - many dendrites and ONE axon extending into PNS
- MOTOR efferents travel along these
Pseudo-unipolar - cell body found in PNS
- Sensory afferents travel along these
What are the 4 main types of glial cells found in the CNS?
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
What are the main functions of each types of glial cell?
Astrocyte - supportive, maintain BBB
Oligodendrocytes - myelination in CNS NOT IN PNS
Microglia - similar to macrophages => Immune monitoring and antigen presentation
Ependymal cells - Ciliated columnar epithalium lining ventricles
Describe how oligodendrocytes myelinate nerve fibres in order to speed up the rate of electrical conduction?
Myelinate sections => leaving small gaps (called nodes of ranvier)
Electrical signals must jump over this gap, which speeds up signal conduction
How do microglia appear in their resting phase compared to a phase where they encounter an insult of infection?
Resting state = short, spiny cell processes
When activated by infection = rounder and more similar to a macrophage
Ependymal cells form a barrier between the CSF and the brain tissue. TRUE or FALSE?
FALSE
CSF can still move outwith ventricles regardless of this layer of epithelium
What are the 2 types of astrocytes and which is found in grey and white matter?
Grey matter - Protoplasmic astrocyte
White Matter - Fibrous astrocyte
What are gyri, sulci and fissures?
Gyri - bulges of cerebral hemispheres
Sulci - indentations (or sunken in parts)
Fissures - DEEP sulci
What is the difference in make up of grey matter and white matter?
Grey Matter = cell bodies of neurons, synapses and support cells
White Matter = axons of neurons, support cells
=> NO CELL BODIES
Roughly speaking where are the grey and white matter found in the brain?
Grey matter covers outside of cerebral hemispheres BUT also makes up important central structures e.g. thalamus
White matter = deep to the grey matter on outside of cerebral hemispheres
Describe the distribution of grey and white matter in the spinal cord?
Grey Matter - H shape (2 anterior horns, 2 posterior horns)
White Matter - Surronds Grey H
What is the function of the central sulcus?
Differentiates regions with different functionalities
e.g. Primary sensory and motor cortexts
Where is the Primary Somatosensory cortex located?
Post-central gyrus
Where is the Primary Somatomotor cortex located?
Pre-central gyrus
What is the corpus callosum?
Large area of white matter carrying material between the RIGHT and LEFT hemispheres of the brain
What is the relevance of the calcarine sulcus?
Marks the location of the primary visual cortex
What is contained in the fornix of the brain and what is its function?
Limbic system found here
Plays a role in memory making
What are the four traditional lobes of the brain?
Frontal
Parietal
Temporal
Occipital
What seperates the frontal and parietal lobes?
The central sulcus
What seperates the frontal and parietal lobe from the temporal lobe?
Lateral sulcus
What seperates the parietal and occipital lobes?
Parieto-occipital sulcus
This is more defined medially than it is on lateral brain
What non-traditional lobe of the brain is found concealed in the cerebral hemispheres, and what is its function?
Insular lobe (insula) - plays a role in patients experience of pain
What 3 layers make up the meninges (superficial to deep)?
- Dura mater.
- Arachnoid mater.
- *Subarachnoid space CSF**
- Pia mater.
Why is it difficult to remove the dura matter from the inner surface of the cranium?
It acts as the periosteum for the inner part of the skull
Describe how the layout of the arachnoid and pia matter create the subarachnoid space
Arachnoid matter = stretched layer over the brain
Whereas pia mater = only 1-2 cells thick, so falls into all the sulci and tightly covers gyri.
=> Space between these 2 layers contains CSF
Why are the lateral ventricles shaped the way they are?
To extend CSF into all traditional lobes of the brain
A blockage in the ventricles or their connections between each other would cause what condition?
Hydrocephalus (back up of CSF being produced)
What could potentially cause a blockage in the ventricular system?
A tumour pressing on the cerebral aqueduct
What other nervous system is often forgotten about in the body?
Enteric (digestive) nervous system
- has its own set of nerve plexuses in gut walls
- influenced by ANS
By which 2 directions is blood supplied to the brain?
- from vertebral arteries
- from internal carotids
What arteries connect the blood supply from vertebral and internal carotid arteries?
posterior communicating arteries
Roughly where do each of the 3 major cerebral arteries supply?
Anterior cerebral a. = medial brain and most of frontal lobe
Middle cerebral a. = lateral brain
Posterior cerebral a. = posterior brain
How is the majority of blood drained from the brain?
dural venous sinuses
- these then drain into the internal jugular vein
Why are there enlargements in the cervical and lumbar regions of the spinal cord?
Increased spinal tissue in these areas to deal with the limbs
At what vertebral level does the spinal cord end, and what is this structure called?
L2
“conus medullaris”
What continues after the conus medullaris in order to connect to the coccyx?
thin connective tissue cord
=> filum terminale
The meninges in the spinal cord are continuous with those in the brain. TRUE/FALSE?
TRUE
however the dura mater in the spinal cord does NOT act as periosteum for the vertebrae. They are seperated by a fat pad known as the epidural space
Describe the distribution of white and grey matter in the spinal cord
“H” of grey matter found centrally (2x anterior horns and 2x posterior horns)
White matter surrounds this
What arteries help to supply blood to the spinal cord?
3 major longitudinal arteries - 2 posterior, 1 anterior
segmental arteries - e.g. intercostal, lumbar
Radicular arteries (travel along ant/post. roots)