CSGD Quiz 2 2003

1

Which one of the following statements about vision is not correct?


  All humans have a blind spot in the nasal quadrants of the visual field of the right eye.

  A tumour of the pituitary could result in the loss of the left visual field in the left eye and the right visual field in the right eye.

  Illuminating a photoreceptor decreases the amount of glutamate that it releases.

  Patients with no green (M) cones can see green coloured objects clearly.

  Raised intracranial pressure can be detected by examining the fundus through an ophthalmoscope.


For each eye, the blind spot is in the temporal quadrants of the visual field.
Extra note: Patients with no green cones can see green objects clearly, but may "confuse" their colours, i.e. visual acuity is unaffected.

2

Which one of the following statements about hair cells in the inner ear is not correct?


  A hair cell that responds best to low frequency sounds will be located at the base end of the basilar membrane.

  Hair cells in the utricle and saccule are able to respond to linear acceleration of the head because calcium carbonate (otoliths or otoconia) increase the density of the gelatinous material (otolithic membrane).

  Hair cells in the utricle and the saccule provide information about the orientation of the head with respect to gravity.

  "Bending" of the stereocilia towards the kinocilium opens mechanically gated ion channels in the hair cells increasing the potassium current and hence changing the membrane potential.

  Hair cells in the ampulla of a semicircular canal (semicircular duct) respond to angular acceleration of the duct because the inertia of the endolymph distorts the cupula.


Hair cells that respond best to low frequency sounds are located at the apical (helicotrema) end of the basilar membrane.

3

Which one of the following statements is not correct?


  Most meningiomas are attached to dura mater.

  Metastatic melanoma in the brain is commonly complicated by haemorrhage.

  Intracranial Schwannomas usually involve the 8th cranial nerve.

  Intracranial ependymomas are situated most commonly in the 4th Ventricle.

  Glioblastoma multiforme is a benign brain tumour.


Glioblastoma multiform is a highly malignant brain tumour with a survival of less than 12 months in most patients.

4

Which one of the following statements is not correct?


  Triplet repeat neurodegenerative disorders are generally late-onset.

  The triplet repeat in Huntington disease usually expands through the maternal line.

  When a triplet repeat expansion occurs in the coding region of a gene it can cause a dominant- negative effect.

  Inheritance of spinocerebellar ataxias is usually autosomal dominant.

  In Friedreich ataxia, iron accumulates in the mitochondria.


The triplet repeat in Huntington disease usually expands through the paternal line.

5

As a group, patients presenting with cerebral infarction have an increased incidence of all but which one of the following:


  Systemic hypertension

  Cardiac valvular disease

  Ruptured saccular cerebral aneurysm

  Cerebral cavernous angioma

  A history of smoking


There is no association between cavernous angioma and cerebral infarction. Cavernous angioma is a congenital lesion which may be responsible for epilepsy. It may be associated with (usually) minor local haemorrhage. The other conditions listed all increase the risk of cerebral infarction.

6

Which one of the following is not characteristic of basal ganglia dysfunction:


  Athetosis

  Rest tremor

  Intention tremor

  Bradykinesia

  Tardive dyskinesia


Intention tremor originates from damage to the cerebellum.

7

Which one of the following statements is not correct?


  Magnetic Resonance Imaging (MRI) is an imaging technique which involves no ionising radiation.

  MRI is superior to Computed Tomography (CT) in the diagnosis of multiple sclerosis.

  Diffusion weighted MRI detects cerebral infarcts earlier than CT and conventional MRI sequences

  CT cannot distinguish infarct from haemorrhage

  Duplex Doppler Ultrasound is a non-harmful method for detecting carotid artery stenoses (narrowing).


CT can distinguish an infarct from a haemorrhage.

8

Which one of the following statements about the cerebral hemispheres is not correct?


  The anterior association cortex is involved in motor planning and cognition.

  Alterations in the structure and/or number of dendritic spines is thought to be involved in learning and memory processes.

  Neurons projecting from the cortex to the spinal cord, basal ganglia and brainstem typically have pyramidally shaped cell bodies, are located mainly in layer 5 and use glutamate as a transmitter.

  In 70% of left-handed people language/speech is represented in the left hemisphere.

  Language appears to be lateralized to a particular hemisphere earlier in females than in males.


Language is lateralized earlier in males than in females.

9

Which one of the following statements about the basal ganglia is not correct?


  Activation of the direct pathway facilitates movement.

  The indirect pathway originates from GABAergic neurons in the caudate/putamen and projects to the external segment of the globus pallidus.

  The globus pallidus is located medial to the putamen, and lateral to the internal capsule.

  The caudate and putamen comprise the input nuclei of the basal ganglia while the substantia nigra pars reticulata and the globus pallidus internal comprise the main output nuclei.

  Projections from the cortex to the striatum (caudate/putamen), and from the main output nuclei to the thalamus are excitatory.


Projections from the cortex to the caudate/putamen are excitatory, but those from the output nuclei of the basal ganglia to the thalamus are inhibitory.

10

Which one of the following statements regarding a lesion of the intracranial segment of nerve VII is not correct?


  It may produce impaired taste sensation to part of the tongue.

  It may result in loss of corneal sensation.

  It may endanger the cornea due to lack of tear production.

  It may result in loss of the corneal reflex.

  It may result in paralysis of the orbicularis oculi muscle.


The facial nerve (VII) does not supply the cornea with somatic sensory fibres.