S1 L1 Topography of the Nervous System Flashcards
What are the different components of the CNS and the PNS?
- CNS cannot regenerate but PNS can
- Cauda equina made up of dorsal and ventral roots
What is white and grey matter?
- Answer on pic on Q side of FC: Name part of the spinal cord which and grey matter
Grey: cell bodies and dendrities. Highly vascularised as metabolically active. In brain there is extra layer of grey matter on outside
White: made of axons and connects grey areas together. Fatty myelin makes it white
In the PNS grey matter is ganglion and white matter is peripheral nerve.
Define the following 3 terms relating to divisions of white matter in the spinal cord:
- Funiculus
- Tracts
- Fasiculus
Funiculus: a segment of white matter which contains axons going up and down the spinal cord
Tracts: connection between two areas of grey matter where the axons are only running in one direction
Fasiculus: subdivision of a tract which supplies a distinct region of the body
How is grey matter in the spinal cord split up?
- Into cell columns called Rexed’s laminae
- Motor neurones supplying a given muscle arise from multiple segments and form a nucleus
What is the definition of a fibre in the CNS and what are the three different types of fibre?
- Fibre: axon in association with its supporting cell e.g oligodendrocyte
- Association fibres connect the same hemisphere, commisural connect right and left hemisphere and projection connect cerebral hemispheres with cord/brainstem
What is a nucleus?
A collection of nerve cell bodies
What is the difference between dorsal and ventral roots?
- Dorsal: sensory
- Ventral: motor
What are the colliculi?
Reflex centre in the midbrain for rapid responses to sound and vision, e.g orientate head towards explosion
What are the functions of the brain stem?
What are the main sulci in the brain and their significance? e.g central
What is the function of the following and where on the inferior aspect of the brain are they located?
- Optic Chiasm
- Uncus
- Medullary Pyramids
- Parahippocampal Gyrus
What is the function of the following:
- Corpus Callosum
- Thalamus
- Cingulate Gyrus
- Hypothalamus
What is the function of the following:
- Fornix
- Tectum
- Cerebellar Tonsil
Spinal Cord:
- How many segments?
- Make up of white and grey matter?
- Clinical link:
- Motor deficit - what would patient complain of? where is lesion?
- Sensory deficit - what would patient complain of? where is lesion?
- Motor and sensory deficit - what would patient complain of? where is lesion?
see pic
Clinical link
• Knowledge of dermatomal and myotomal supply allows localisation of lesions to a given cord segment(s)
• A motor deficit in a myotome pattern without sensory defects suggests the lesion is at the level of ventral nerve routes
• A sensory deficit in a dermatomal pattern without any motor issue suggests the lesion is at the level of dorsal roots
A mixture of motor and sensory deficits suggests the lesion at the level of the spinal nerve
• A sensory deficit across multiple segments may suggest a cord lesion
• A sensory deficit in a homuncular pattern may suggest a lesion above the thalamus
(see sensory system)
Production and circulation of CSF:
- What are brain ventricles?
- What produces CSF?
- Functions of CSF?
- Reabsorbed where?
- Draw out the ventricular system
Explain the order of flow of CSF through the ventricles
Where could a blockage occur?
Consequence of a blockage?
Q side of FC: Don’t look at until answered this FC
GW (But contains a lot of stuff that also need to know and isn’t covered already)
What issues can arise due to the cerebral aqueduct?
Really narrow so can get occluded and cause dilation of superior structures leading to hydrocephalus
What is a Jacksonian seizure?
Focal partial seizure starting in one area that can move proximally through the body as the seizure spreads down cortical homunculus
How is hydrocephalus treated?
Ventriculo-peritoneal shunt
Draw a diagram of a reflex arc.
Synapses in the ventral horn
What is the Jendrassik reflex?
Why does this meningioma show up when using Gd contrast and why does it need to be removed even though it is benign?
- Contrast is absorbed by the lesion as has caused a break in the BBB so can get through
- Could cause herniation and Cushing’s reflex so needs to be removed
What are the different types of spina bifida and how can you prevent this condition occuring?
- Take folate supplements 3 months before concieving to prevent this and cleft palate defects
- Myelomeningocele is the msot dangerous
What is the abnormality in this CT and how should this patient be treated?
- Dilation of the lateral ventricles as the cerebral aqueduct is blocked so hydrocephalus is occurring as impairment of CSF drainage
- Ventriculoperitoneal shunt
Where are the following in the brain:
- Telencephalon (Cerebrum)
- Diencephalon
- Mesencephalon
- See picture
- Just below septum pellucidum
- Midbrain
Where are the following anatomical ares of the brain:
- Cingulate gyrus
- Uncus
- Parahippocampal gyrus
- Parieto-occipital sulcus
Where are the anterior and posterior commisures of the brain and what is their function?
Connects lobes of the two hemispheres
Where is the pineal gland located?
What is the cervical and lumbar enlargement?
Cervical: corresponds with the attachments of the large nerves which supply the upper limbs. It extends from about the fifth cervical to the first thoracic vertebra
Lumbar: widened area of the spinal cord that gives attachment to the nerves which supply the lower limbs. It commences about the level of T11 and ends at S2
What is the lumbar cistern?
Subarachnoid space in the lower lumbar spinal canal
