Group work questions Flashcards
Which structures detect muscle stretch when the tendon hammer is applied to the patellar ligament?
stretch receptors found in muscle spindle
In monosynaptic reflexes like the knee jerk, where is the synapse found?
grey matter of spinal cord
Draw a labelled diagram showing the complete reflex arc.
What spinal level(s) mediate(s) the knee jerk reflex?
L2,L3, L4
Jendrassik manoeuvre
used to elicit reflex - prevents some unconscious inhibition
- ask patient to clench teeth and hands and then try to elicit the reflex
Whilst out shopping you witness a man collapse and start having a seizure. As a medical student you attend to the man during the interval before an ambulance arrives.
You notice that the man’s seizure started in his left hand, but then progressively moved proximally through his upper limb. Why is this the case
- damage to the primary motor cortex in the region controlling the hands
- damage/ischaemia may spread to areas of the cortex near this region e.g. up the arm
- think homonculus
if there are motor problems with the left hand which side of the brain is there likely to be an abnormality?
right side of the brain
- primary motor cortex neruones decussate to form the cortical spinal tract at the level of the pyramidal medullas
how do T1 and T2 MRI scan differ
T1- fluid is dark and fat is white
T2- fluid is white and fat is darker
describe what you can see?
Why does gadolinium (Gd) enhance the lesion?
a tumour derived from fat/protein e.g. meiningioma
Gd acts as a contrast to amke tumours, blood vessels and organs more enhanced–> due to 7 unpaired electrons (the most possible)
A baby is born with a prominent lump on her back at the lumbar level. Her mother did not take folate supplements during her pregnancy. She appears to be neurologically normal. The lump is fluid filled and transilluminates very well.
What is the fluid present in the lump likely to be?
CSF
A baby is born with a prominent lump on her back at the lumbar level. Her mother did not take folate supplements during her pregnancy. She appears to be neurologically normal. The lump is fluid filled and transilluminates very well.
Why does the baby not have neurological deficit?
Meningocele–> spinal cord is found within normal place in the vertebra
Which type of spina bifida has a worse prognosis?
craniorachischisis
The arrow is pointing to part of the ventricular system which is narrowed. Which part is this
cerebral aqueduct (sylvius)
- build up of CSF in the lateral and 3rd ventricle
- compresses brain structures- hydrocephaly
ways of treating hydrocephaly
- shunt- which drains the CSF into the peritoneal cavity in the abdomen using a tube (tube is quite long to account for growth (ventriculoperitoneal shunt)
- endoscopic third ventircuolostomy- holes created so that CSF can draining into the subarachnoid space
You help a plaster technician to apply a cast to a patient’s leg. He complains initially of some skin irritation but when you see him in fracture clinic the following day he states he feels comfortable, with no irritation.
What is the neurophysiological mechanism for this phenomenon?
radidly adapating sensory neurpones
- AP frequency goes from high to low
You are assisting in theatre with a resection of a brain tumour arising from the cerebral cortex. The neurosurgeon states that the patient’s sensory function in their right hand is likely to be impaired.
Ascertain as precisely as possible where in the brain the tumour is likely to be.
supero -lateral
why is the hand particularly vulnerable
part of the primary somatosensory cortex responsible for the hand takes up a large proportion compared to other parts of the body
v
A patient with diabetic neuropathy is found to have bilateral ‘glove and stocking’ paraesthesia in both hands and feet.
Can this pattern be explained by a single lesion affecting the sensory homunculus in the primary sensory cortex? If not, why not?
no- a single lesion could not explain bilateral paraesthesia in both hands and feet
- typical od diabetes due to distal bilateral neuropathy –> metabolic disturbances (DM and alcoholism) cause neuropathy
Further examination of the same patient reveals that they have complete sensory loss (all modalities) in the S1 dermatome on the right side as well as weakness in plantarflexion.
Which structure(s) might have been damaged to cause this isolated dermatomal loss and accompanying weakness? Draw a diagram showing these potential site(s)
the spinal nerve (both sensory and motor neurones)
label this
which region of the cord has been affected
dorsal region (more sensory)
Subacute combined degeneration of the spinal cord what can a vegan diet cause and why
Subacute combined degeneration of the spinal cord - deficiency in B12
He initially presented with sensory ataxia. What is this?
sensory ataxia leads to a lack of muscle coordiantion caused by a loss of the sense of where diff parts of the body are located in relation to one another (proprioception)
A 30 year old woman presents to the neurology clinic with ‘numbness’ affecting both of her upper limbs and the upper half of her chest.
Sensory examination reveals she has bilateral loss of pinprick and temperature sensation in the totality of her C4-T2 dermatomes. Vibration, light touch and two point discrimination are preserved.
Which sensory system is affected?
spinothalamic system
