Week 1 - Wet Room Flashcards
What is the brainstem?
The brainstem is the part of the brain that lies just superior to the spinal cord. It is made up of 3 parts. From superior to inferior they are: -The midbrain -The pons -The medulla
Which cranial cavity does the brainstem lie in?
Posterior cranial fossa
Embryologically, which two vesicles of the neural tube give rise to the brainstem?
Metencephalon
Myelencephalon
What are the cavities (of the ventricular system) that lie within the brainstem?
4th ventricle
Cerebral aqueduct
Which cranial nerves can you see emerging from the pontomedullary junction?
VI, VII and VIII
Which of the cranial nerves that emerge from the pontomedullary junction has the longest intracranial course?
Facial nerve (VII)
Why is it clinically significant to know that the Facial nerve is so long?
Its long intracranial course makes this nerve very vulnerable to injury by increased intracranial pressure or other mechanical factors such as intracranial fractures or cerebral artery aneurysms.
Damage to this nerve will cause Bell’s palsy
Even though the actual pathology is increased intracranial pressure, the manifestation due to the nerve involved is far removed.
This can be a misleading clinical presentation and is hence called as a false localising sign.
What produces the pyramids of the brainstem?
Descending fibres of ipsilateral cerebral cortex
What produces the decussation of the pyramids?
75-90% of descending fibres cross over
What produces the olive and what is its function?
Has connections primarily with the cerebellum
Involved in control of movement
The medulla has an open and a closed part.
Which is superior and which is inferior?
Open = superior Closed = inferior
What structure does the “open” part of the medulla open onto?
IV ventricle posteriorly
Through which foramen does the medulla pass to become the spinal cord?
Formen magnum
What makes up the diencephalon?
Thalamus and hypothalamus
How many part of the diencephalon can you see?
Most of the structures are deep and cannot be seen from the surface except for a small part of the hypothalamus
What is the name given to the midline structure connecting the two cerebellar hemispheres?
Vermis
What are the 3 lobes of each cerebellar hemisphere?
Anterior lobe
Posterior lobe
Flocculonodular lobe
What parts of the brain is the cerebellum connected to anatomically be peduncles?
Medulla
Pons
Midbrain
What is the name of the ventricular space that lies immediately anterior to the cerebellum?
4th Ventricle
What cranial cavity if the cerebellum in contact with?
Posterior cranial fossa
What foramen of the skull does the cerebellum sit above?
Foramen magnum
The part of the cerebellum that sits atop this foramen is called the cerebellar tonsils
What may occur to the tonsils when there is a sudden drop in intracranial pressure?
The tonils may herniate through the foramen magnum
This is called cerebellar coning
What is the overall structure of the cerebral hemispheres?
The cerebral hemispheres are paired (left and right) with a deep, but incomplete, fissure separating the two parts in the mid-sagittal line.
What is the neame given to the large fissure separating the two cerebral hemispheres?
Median Longitudinal Fissure
What structure connects the two hemishperes of the cerebrum?
Corpus callosum
What nerve types are most likely to be carried in the corpus callosum?
Commissural fibres (connect two hemispheres)
Contrast to:
- Association fibres (connect regions within same hemisphere)
- Projection fibres (connect connect each region to other parts of the brain or the spinal cord)
Describe how the brain sits in the cranial cavity
On removal of the skull cap, and the encasing meninges, the cerebral hemispheres appear to occupy the whole of the cranial cavity from anterior to posterior and from side to side.
The cerebral hemispheres sit on the floor of the anterior cranial fossa and the middle cranial fossa.
However, posteriorly, the cerebral hemispheres sit on the tantrum cerebella which is a fold of dura mater which covers over the cerebellum.
What lobe contains the primary motor cortex?
Frontal
What lobe contains the primary visual cortex?
Occipital
What lobe contains the primary sensory cortex?
Parietal
What lobe contains the primary auditory cortex?
Temporal
When removing the laminae from the vertbrae to gain access to the vertebral canal, what is the first thing you would encounter on entering the vertebral canal?
Dura Mater
At what level does the spinal cord terminate in the adult and the newborn?
Adult = L1-L2
The newborn = L3
At what vertbral level does the dura and arachnoid mater terminate?
S2
What happens to the pia mater inferior to the spinal cord?
Becomes the cauda equine
What occupies the space between the end of the spinal cord and the termination of the dura and arachnoid?
CSF and cauda equina
Lumber puncture can be performed here at level L3 or L4
How many pairs of spinal nerves are there?
31
What is the difference between upper motor neurone damage and lower motor neurone damage?
Upper motor neurone lesions are characterised by spasticity, an increase in muscle tone and complex sensory syndromes.
Lower motor neurone conditions are characterised by global sensory changes and or flaccid paralysis depending on the nature of the mixed peripheral nerves
Is damage to the cauda equina classified as an upper or lower motor neurone?
Lower motor neurone
