Pre Clinical Medical Science SBAs
Pre Clin CNS: (104 questions)

Questions

• 1
  What is contained in the dorsal root ganglion?
  Difficulty: Easy     Topic: Dorsal root ganglion
  a

  1st synapse in dorsal column pathway

  b

  1st synapse in spinothalamic pathway

  c

  Cell bodies of 1st order afferents

  d

  Cell bodies of 2nd order afferents

  e

  Cell bodies of 2nd order efferents
  Explanation: A ganglion is a collection cell bodies outside the CNS. The dorsal root ganglion is a location of cell bodies of the primary afferent neurones. The 1st synapse in dorsal column pathway is in the dorsal horn at the level of entry; for the dorsal columns it is in medullary nuclei. 2nd order afferents have their cell bodies at the locations of the synapses as described above. Efferents do not pass through the dorsal root.
• 2
  In which sensory pathway is the first synapse at the level of the medulla?
  Difficulty: Medium     Topic: Sensory pathways 1
  a

  Dorsal columns

  b

  Lateral spinothalamic

  c

  Spinocerebellar

  d

  Tectospinal

  e

  Ventral spinothalamic
  Explanation: In the dorsal column pathway: the primary neurone ascends ipsilaterally in the dorsal columns to the nuclei fasiculus and gracilis where a synapse occurs. The cell body of the second order neurone is located here, which immediately decussates and ascends to the thalamus, where the tertiary neurone is located. All spinothalamic and spinocerebellar synapse in the spinal cord. Tectospinal tract is motor.
• 3
  Which ascending pathway carries vibration sense?
  Difficulty: Easy     Topic: Sensory pathways 2
  a

  Dorsal columns

  b

  Lateral spinothalamic

  c

  Rubrospinal

  d

  Spinocerebellar

  e

  Ventral spinothalamic
  Explanation: The dorsal columns transmit 2 point discrimination, vibration and proprioception. Spinothalamic is specific to pain and temperature. Spinocerebellar is needed for truncal proprioception. The rubrospinal tract is a motor pathway.
• 4
  In a right-sided, thoracic hemisection of the cord, which sensory modality will be lost from the left leg but not the right?
  Difficulty: Hard     Topic: Cord hemisection
  a

  Gross pressure

  b

  Pain

  c

  Proprioception

  d

  Two-point discrimination

  e

  Vibration
  Explanation: Cord hemisection causes a Brown-Sequard syndrome where below the level of the lesion there is: ipsilateral loss of dorsal column function and upper motor neurone innervation, plus contralateral loss of spinothalamic function. This is due to the position of pathway decussation.
• 5
  How does a receptor potential differ from an action potential?
  Difficulty: Easy     Topic: Receptor potential
  a

  It determines the line code

  b

  It results in depolarisation

  c

  It is caused by ion influx

  d

  It is graded to stimulus intensity

  e

  It is only present in unmyelinated neurones
  Explanation: When a stimulus is transduced, the receptor activated causes a receptor potential. This is transient depolarisation that decays and is graded to stimulus intensity, such that a larger stimulus causes a larger depolarisation - unlike action potentials that code intensity by frequency. The line code is the modality that a neurone conveys. Both receptor and action potentials may be depolarisations, caused by ion movement and both can occur in unmyelinated neurones.
• 6
  What is the structure of neurones that convey only somatic pain?
  Difficulty: Medium     Topic: Fibre types
  a

  Large diameter, myelinated

  b

  Large diameter, unmyelinated

  c

  Mediate diameter, myelinated

  d

  Small diameter, myelinated

  e

  Small diameter, unmyelinated
  Explanation: The sensory modality of pain is conveyed by two fibre types: A-delta and C-fibres. A-delta fibres may also be activated by innocuous, non-painful pressure however C-fibres only transmit pain. C-fibres are small and unmyelinated. A-delta are small but myelinated. Fibres that convey proprioceptive information (A-beta) are large and myelinated.
• 7
  What is the name given to superficial, rapidly adapting receptors that respond to vibration?
  Difficulty: Hard     Topic: Sensory endings
  a

  Free nerve ending

  b

  Meissner corpuscle

  c

  Merkel disc

  d

  Pancinian corpuscle

  e

  Ruffini ending
  Explanation: There are 5 main cutaneous receptors that respond to pressure and vibration. Meissner's (superficial) and Pancinian (deep) corpuscles are rapidly adapting whilst Merkel's discs (superficial) and Ruffini's endings (deep) are slowly adapting. Free nerve endings can respond to many sensory modalities.
• 8
  What is the stimulus to activation of a muscle spindle?
  Difficulty: Easy     Topic: Muscle spindle
  a

  Anticipated contraction

  b

  Anticipated stretch

  c

  Excessive force through a tendon

  d

  Unexpected stretch

  e

  Unilateral pain
  Explanation: Muscle spindles are comprised of sensory axons wrapped around intrafusal muscle fibres. Unexpected stretch to the muscle (and the axons) causes activation of the afferent neurones, which signal via a monosynaptic reflex arc to cause contraction of the same muscle. The response is modulated by extrafusal muscle fibre contraction, under the action of gamma motor neurones.
• 9
  High threshold, mechanical noiceptors signal through which afferent fibre type?
  Difficulty: Medium     Topic: Noiceceptors
  a

  A-alpha fibres

  b

  A-beta fibres

  c

  A-delta fibres

  d

  A-gamma fibres

  e

  C fibres
  Explanation: Noiceception is the sensory component of pain. There are two forms of noiceceptor (receptors that transduce pain): mechanoreceptors and polymodal receptors. Mechanoreceptors are high-threshold and only respond to pressure - they are innervated by A-delta fibres. Polymodal receptors have many stimuli and are innervated by C-fibres.
• 10
  What is the role of the substantia gelatinosa?
  Difficulty: Hard     Topic: Substantia gelatinosa
  a

  Extracellular matrix in the spinal cord

  b

  Location of synapse for dorsal column primary neurones

  c

  Location of synapse for spinothalamic primary neurones

  d

  Permits decussation in the medulla

  e

  Permits decussation in the spinal cord
  Explanation: The substantia gelatinosa is lamina II of the dorsal horn. It is the location of the cell bodies of second order spinothalamic neurones, where primary afferents synapse. Both C-fibres and A-delta fibres synapse here therefore it is an important location for the central transmission of pain. It is thought to play a key role in the gate control theory of pain.
• 11
  How is the gate control theory of pain most accurately described?
  Difficulty: Medium     Topic: Gate control theory of pain
  a

  Experience of pain requires a threshold to be exceeded

  b

  Pain is influenced by ascending and descending influences, controlled at the spinal cord

  c

  Peripheral sensitisation increases pain experienced

  d

  Spinal cord sensitisation increases pain experienced

  e

  Thalamic inhibition can block ascending pain afferents
  Explanation: Melzack and Wall proposed the gate control theory of pain, which describes pain as a multifaceted experience that is controlled at a spinal cord level. There are ascending inputs that increase the perception of pain (C-fibres and A-delta-fibres) as well as ascending A-beta fibres that inhibit pain sensation. Descending higher influences are important in helping to reduce the pain experienced.
• 12
  What is allodynia?
  Difficulty: Medium     Topic: Allodynia
  a

  Increase in pain of a normally painful stimulus

  b

  Inhibition of pain at spinal cord level

  c

  Pain from a normally painless stimulus

  d

  Process of central sensitisation

  e

  Process of peripheral sensitisation
  Explanation: Allodynia is the term given to the experience of pain following stimulation by a normally non-painful stimulus. This is in contrast to hyperalgesia, which is an increase in pain from a normally painful stimulus.
• 13
  What ion is commonly implicated in primary hyperalgesia?
  Difficulty: Hard     Topic: Primary hyperalgesia
  a

  Ca2+

  b

  Cl-

  c

  H+

  d

  Mg2+

  e

  Na+
  Explanation: Primary hyperalgesia is the process of increasing pain perceived due to modulation of noiceceptors at the site of injury. Factors released by damaged tissue and inflammatory cells act on polymodal noiceceptors to reduce their threshold, increasing pain experienced. Acidic conditions (H+), prostaglandins and substance P are of particular importance in this process.
• 14
  What is the key event in facilitating central sensitisation of pain?
  Difficulty: Hard     Topic: Secondary hyperalgesia
  a

  Calcium entry through AMPA receptors

  b

  Calcium entry through NMDA receptors

  c

  Calcium entry through substance P receptors

  d

  Sodium entry through AMPA receptors

  e

  Sodium entry through substance P receptors
  Explanation: Central sensitisation is the process that increases pain experienced due to modulation of the synaptic connection between the primary afferent and spinothalamic secondary. Substance P (SP) is released from the primary neurone and binds SP-receptors, which results in removal of a Mg2+ block from NMDA receptors on secondary neurones. When NMDA receptors open (by binding glutamate) calcium enters, which signals through secondary messengers to increase proximal transmission.
• 15
  Through what mechanism does ibuprofen exert most of its analgesic action?
  Difficulty: Medium     Topic: Ibuprofen
  a

  Increased leukotriene production

  b

  Inhibition of IL-1 signalling

  c

  Inhibition of IL-6 production

  d

  Reduction in central sensitisation

  e

  Reduction in peripheral sensitisation
  Explanation: Ibuprofen is a non-steroidal anti-inflammatory drug (NSAID) that acts by causing competitive inhibition of cyclo-oxygenase (COX). This enzyme is needed for production of prostaglandins, which increases at the site of injury where they causes peripheral sensitisation. NSAIDs slightly increase leukotriene production, but this would increase inflammation. Inhibiting IL-1 signalling gives the anti-pyretic effects of NSAIDs. There is no effect on IL-6 production. Central sensitisation is not dependent on prostaglandins.
• 16
  Which intracellular signalling cascade is triggered by activation of opioid receptors?
  Difficulty: Hard     Topic: Opioid 3
  a

  Activation of adenylate cyclase and depolarisation

  b

  Activation of adenylate cyclase and hyperpolarisation

  c

  Activation of guanylate cyclase and hyperpolarisation

  d

  Inhibition of adenylate cyclase and hyperpolarisation

  e

  Inhibition of adenylate cyclase and hyperpolarisation
  Explanation: Opioids are depressant drugs and ligation of opioid receptors results in cell hyperpolarisation. Delta, mu and kappa opioid receptors are G-protein coupled receptors, which cause inhibition of adenylate cyclase. cAMP levels fall, which results in opening of K+-channels, and hyperpolarisation due to potassium efflux.
• 17
  What effects do opioids have outside the CNS?
  Difficulty: Easy     Topic: Opioids 1
  a

  Contraction of dilator papillae

  b

  Increased CO2 sensitivity

  c

  Reduced GI motility

  d

  Shivering

  e

  Sweating
  Explanation: Opioids have a number of effects: pupil constriction, analgesia, sedation, euphoria, physical dependence, reduced GI motility and reduced CO2 sensitivity. The fall in sensitivity to CO2 is the mechanism for respiratory depression in opioid overdose. Shivering and sweating are features of opioid withdrawal.
• 18
  How do opioids cause euphoria?
  Difficulty: Hard     Topic: Opioids 2
  a

  Activation of hippocampus

  b

  Activation of thalamus

  c

  Disinhibition of amygdala

  d

  Disinhibition of nucleus accumbens

  e

  Inhibition of red nucleus
  Explanation: Opioids are depressant drugs that cause hyperpolarisation of target neurones. They result in euphoria by reducing GABAergic transmission from interneurones from the ventral tegmental area (of the midbrain) to the nucleus accumbens. This has the effect of increasing activity in dopaminergic neurones in the limbic system, which causes euphoria.
• 19
  Why can black-white vision function in lower light levels than colour vision?
  Difficulty: Medium     Topic: Low light vision
  a

  Cones have more photopigment discs

  b

  Lower density of rhodopsin in rods

  c

  Multiple rods connect to each ganglion cell

  d

  Rods have a shorter outer segment

  e

  Rods produce larger action potentials
  Explanation: Rods are the photoreceptors that detect light (black-white) whereas cones are used to detect colour. Rods have a longer outer segment, which contains more photopigment discs and rhodopsin, so are more sensitive to light than cones. Also, multiple rods converge onto one ganglion cell, which increases the chance of firing an afferent impulse compared to cones that have a 1:1 connection. Photoreceptors do not have action potentials, they only depolarise. Ganglion cells may fire action potentials.
• 20
  In the retina, which cell type lies closes to the pigmented epithelium (and furthest away from the pupil)?
  Difficulty: Easy     Topic: Retinal structure
  a

  Amacrine cell

  b

  Bipolar cell

  c

  Ganglion cell

  d

  Horizontal cell

  e

  Photoreceptors
  Explanation: Photoreceptors are adjacent to the retinal pigment epithelium, furthest away from the pupil. Anterior to these cells are bipolar cells, which are important in integration and retinal processing. Finally, anterior to these are the ganglion cells, whose axons pass to the optic disc to form the optic nerve. Amacrine and horizontal cells lie between the bipolar and ganglion cells.
• 21
  What changes occur to photoreceptors in the presence of light?
  Difficulty: Hard     Topic: Photoreceptors 1
  a

  Increased calcium influx and hyperpolarisation

  b

  Increased potassium efflux and hyperpolarisation

  c

  Increased sodium influx and depolarisation

  d

  Reduced potassium efflux and depolarisation

  e

  Reduced sodium influx and hyperpolarisation
  Explanation: Photoreceptors hyperpolarise in the presence of light in a cGMP-dependent manner. Rhodopsin, the photopigment, is made of retinal (a chromophore that responds to light) and opsin (a G-protein). Light causes activation of opsin, which increases PDE activity. This reduces intracellular cGMP, causing closure of cGMP-dependent sodium channels. Sodium influx reduces and the membrane hyperpolarises.
• 22
  What transmitter is released by photoreceptors?
  Difficulty: Hard     Topic: Photoreceptors 2
  a

  5-HT

  b

  ACh

  c

  GABA

  d

  Glutamate

  e

  Substance P
  Explanation: Photoreceptors release glutamate when depolarised, therefore in the presence of light glutamate release is reduced as the photoreceptors hyperpolarise. ACh is little used in the CNS.
• 23
  Where do retinal ganglion cells synapse?
  Difficulty: Medium     Topic: Visual pathway
  a

  Inferior colliculus

  b

  Lateral geniculate nucleus

  c

  Optic radiation

  d

  Superior olivary nucleus

  e

  Ventromedial thalamus
  Explanation: The central visual pathway begins at the retina with the axons of ganglion cells passing down the optic nerve. The fibres from nasal retina cross over at the optic chiasm. The optic tract connects the chiasm to the lateral geniculate nucleus of the thalamus, where ganglion cells synapse. The afferent fibres from here pass through the optic radiation to the visual cortex in the occipital lobe.
• 24
  Which special sense has multiple different receptors on each sensory cell?
  Difficulty: Easy     Topic: Special senses
  a

  Hearing

  b

  Sight

  c

  Smell

  d

  Taste

  e

  Vision
  Explanation: Gustatory sensory cells are located on the lateral walls of tongue papillae. Each cell contains many taste receptors and each receptor is able to respond to one modality. There are 5 main taste modalities: sweet, sour, salt, bitterness and umami. In contrast, each olfactory cell only responds to one smell and there are many different olfactory cells.
• 25
  Where is the primary gustatory cortex located?
  Difficulty: Easy     Topic: Gustatory cortex
  a

  Brainstem

  b

  Cerebellum

  c

  Frontal lobe

  d

  Insular cortex

  e

  Occipital lobe
  Explanation: The primary gustatory cortex is located on the insular cortex of the temporal lobe. The olfactory and auditory cortices are also in the temporal lobe. The primary visual cortex is in the occipital lobe.
• 26
  Which special sense has full bilateral processing for unilateral stimuli?
  Difficulty: Hard     Topic: Special senses
  a

  Hearing

  b

  Sight

  c

  Smell

  d

  Taste

  e

  Vision
  Explanation: Sound stimuli from each ear is processed bilaterally. Hair cells in the inner ear activate the dorsal and ventral cochlear nerves. The ventral cochlear nerve makes bilateral connections in the superior olivary nucleus. The pathway from both dorsal and ventral nerves pass to the inferior colliculus and then to the auditory cortex. Nasal retina fibres cross over but there is contralateral processing of visual fields, not bilateral.
• 27
  A complete lesion of which structure causes a bilateral right hemianopia?
  Difficulty: Medium     Topic: Visual field defects
  a

  Left optic nerve

  b

  Left optic radiation

  c

  Optic chiasm

  d

  Right occipital cortex

  e

  Right optic tract
  Explanation: After the optic chiasm (optic tract, lateral geniculate nucleus, optic radiation and visual cortex), each visual field is contained in the contralateral visual pathway. Therefore a complete lesion of any of these structures causes a contralateral hemianopia. Optic nerve lesions cause hemianopsia with absence of all sight from one eye. An optic chiasm lesion typically causes a bitemporal hemianopia.
• 28
  What is a central pattern generator?
  Difficulty: Medium     Topic: Central pattern generators
  a

  A signalling molecule involved in neuronal positioning

  b

  Afferent impulses that bridge from descending motor efferents

  c

  Circuits that connect visual guidance with movement

  d

  Spinal cord circuits for repetitive movements

  e

  Part of cerebellum used for motor learning
  Explanation: Central pattern generators (CPG) are local circuits within the spinal cord that are used to control repetitive movements without need for higher input. For example, using proprioceptive input CPG will maintain walking but not initiate or stop locomotion.
• 29
  Which motor pathway is most important in supply of distal limb flexors?
  Difficulty: Easy     Topic: Distal flexor innervation
  a

  Corticospinal

  b

  Medullary reticulospinal

  c

  Pontine reticulospinal

  d

  Rubrospinal

  e

  Tectospinal
  Explanation: Descending pathways are grouped into the lateral and ventromedial pathways. The lateral pathways are the corticospinal and rubrospinal pathways. The corticospinal pathway has the dominant role, particularly in innervation of distal and flexor muscles for fine movements. The other pathways listed are the ventromedial pathways, which are needed for postural control and head/eye movements.
• 30
  Where does the tectospinal tract originate?
  Difficulty: Medium     Topic: Tectospinal tract
  a

  Amygdala

  b

  Inferior olivary nucleus

  c

  Lateral geniculate nucleus

  d

  Mamillary bodies

  e

  Superior colliculus
  Explanation: The tectospinal tract originates from the superior colliculus in the midbrain, which receives input from both the visual and auditory central pathways. The tectospinal tract controls head movement in response to visual & auditory stimuli. The amygdala and mamillary bodies are part of the limbic system. The inferior olivary nucleus is a deep cerebellar nucleus. The lateral geniculate nucleus (of the thalamus) is part of the central auditory pathway.
• 31
  Which nucleus is responsible for parasympathetic supply in the 3rd cranial nerve?
  Difficulty: Medium     Topic: -
  a

  Edinger-Westphal nucleus

  b

  Lateral geniculate nucleus

  c

  Nucleus accumbens

  d

  Nucleus ambiguus

  e

  Nucleus tractus solitarius
  Explanation: The occulomotor nerve carries motor parasympathetic efferents that pass to constrictor pupillae to cause pupil constriction. In response to light on the retina, there is bilateral activation of the Edinger-Westphal nuclei (in the midbrain), which is the origin of the parasympathetic nerves. The lateral geniculate nucleus is the location of synapse for retinal ganglion cells. The nucleus accumbens is part of the limbic system. The nucleus ambiguus is the origin of the Vagus. The nucleus tractus solitarius is an important structure in sympathetic supply.
• 32
  What collection of clinical features are found in an upper motor neurone lesion?
  Difficulty: Easy     Topic: UMN lesion
  a

  Hypertonia, hyperreflexia, up-going plantars

  b

  Hypertonia, hyporeflexia, down-going plantars

  c

  Hypertonia, hyporeflexia, up-going plantars

  d

  Hypotonia, hyperreflexia, up-going plantars

  e

  Hypotonia, hyporeflexia, down-going plantars
  Explanation: Damage to an upper motor neurone causes: hypertonia, hyperreflexia and up-going plantars (extensor Babinski response). In contrast to a lower motor neurone lesion that causes: hypotonia, hyporeflexia, down-going plantars, muscle wasting and fasiculations. Fibrillations may also be seen on electromyography in lower motor lesions. Both upper and lower lesions cause weakness.
• 33
  Which part of the brain is most important for sequencing of movements?
  Difficulty: Hard     Topic: Sequencing movements
  a

  Basal ganglia

  b

  Cerebellum

  c

  Premotor area (area 6)

  d

  Primary motor cortex (M1)

  e

  Supplementary motor area (area 4)
  Explanation: There are several accessory motor areas that feed into the primary motor cortex (M1). The pre-motor area is important for sequencing, planning and initiating movement. The supplementary motor area has a particular role in bilateral co-ordination. The basal ganglia influences the speed and amount of motor activity. The cerebellum is needed for fine control, judging speeds and distances, and for motor learning. The primary motor cortex provides descending output through the corticospinal tract.
• 34
  Truncal ataxia is a feature characteristic of damage to which part of the brain?
  Difficulty: Hard     Topic: Truncal ataxia
  a

  Basal ganglia

  b

  Cerebellum

  c

  Dorsal columns

  d

  Limbic system

  e

  Primary motor cortex
  Explanation: The cerebellum is particularly important in controlling posture by innervating the axial muscles through the reticulospinal, vestibulospinal and rubrospinal pathways. The input to this is the spinocerebellar pathway. A loss of this function causes truncal ataxia. The dorsal columns are most important for proprioception of the distal limbs. Basal ganglia damage causes hyperkinesia or bradykinesia. Limbic system damage affect emotion and memory. Primary motor cortex damage causes the typical features of a stroke.
• 35
  What is the main role of cerebellar vermis?
  Difficulty: Medium     Topic: Cerebellar vermis
  a

  Conjugation of eye movements

  b

  Control fine flexor movement

  c

  Control force and timing of movements

  d

  Influence speed of movement initiation

  e

  Maintain posture and head position
  Explanation: The cerebellum can be divided into anatomical sections: two hemispheres and vermis plus deep nuclei. Or functional segments, the spinocerebellum, vestiubulo-cerebullum and cerebro-ponto-cerebellum. The vermis is responsible for the first two of these, which is predominantly posture and head position. The brainstem is most important for eye movement conjugation. The cortex controls fine flexors. The cerebellar hemispheres control force & timing. The basal ganglia influence speed & movement initiation.
• 36
  Which cell type is most numerous in the cerebellar cortex?
  Difficulty: Hard     Topic: Cerebellar cortex
  a

  Betz cells

  b

  Climbing fibre

  c

  Granular cell

  d

  Mossy fibre

  e

  Purkinje cell
  Explanation: The cerebellar hemispheric cortex has a complex structure to allow comparison of intended with actual movements, and production of a correction output. This is the function of the cerebro-ponto-cerebellum. The granular cell is highly numerous and has many parallel fibre projections that run along the length of the cortex. These form multiple synapses with Purkinje cells, where integration occurs and supply the output. Climbing fibres and mossy fibres provide the ‘actual’ and ‘intended’ action information. Betz cells are the most numerous cells in the primary motor cortex.
• 37
  What collective term is given to the caudate nucleus and putamen?
  Difficulty: Easy     Topic: Caudate and putamen
  a

  Globus pallidus

  b

  Limbic system

  c

  Striatum

  d

  Substantia nigra

  e

  Subthalamic nucleus
  Explanation: Other than the limbic system, all other structures listed above form the basal ganglia. The caudate nucleus and putamen are functionally connected and termed as the striatum. The globus pallidus is anatomically and functionally divided into the globus pallidus interna and externa. The limbic system is comprised of: amygdala, nucleus accumbens, hippocampus, mamillary bodies and parts of the hypothalamus. The substantia nigra is divided into the pars compacta and pars reticularis.
• 38
  How does dopamine influence the direct pathway of the basal ganglia?
  Difficulty: Easy     Topic: Dopamine in basal ganglia
  a

  Increase pathway activity to inhibit movement

  b

  Increase pathway activity to promote movement

  c

  No effect

  d

  Reduce pathway activity to inhibit movement

  e

  Reduce pathway activity to promote movement
  Explanation: The direct pathway of the basal ganglia acts to promote movement by activating the thalamo-cortical relay. The indirect pathway has the opposite effect, reducing movement. Nigro-striatal neurones releasing dopamine increase movement by activating the direct pathway and inhibiting the indirect pathway.
• 39
  Which of the following is NOT a core feature of idiopathic Parkinson disease?
  Difficulty: Easy     Topic: Parkinson disease 1
  a

  Bradykinesia

  b

  Postural instability

  c

  Rigidity

  d

  Tremor

  e

  Weakness
  Explanation: The key features of idiopathic Parkinson disease are bradykinesia, rigidity, tremor and postural instability (causing falls). Weakness is not part of idiopathic Parkinson disease.
• 40
  What pathological feature is characteristic of Parkinson disease?
  Difficulty: Easy     Topic: Parkinson disease 2
  a

  Aschoff bodies

  b

  Barr bodies

  c

  Hirano bodies

  d

  Kimmelstiel-Wilson nodules

  e

  Lewy bodies
  Explanation: Idiopathic Parkinson disease is caused by loss of dopaminergic nigro-striatal neurones. In the remaining neurones an eosinophilic inclusion bodies may be seen, called Lewy bodies. Aschoff bodies are found in rheumatic fever. Barr bodies are inactive X-chromosomes in cells containing two X-chromosomes. Hirano bodies are found in Alzheimer disease. Kimmelstiel-Wilson nodules are found in diabetic nephropathy.
• 41
  What molecule is dopamine synthesised from?
  Difficulty: Hard     Topic: Dopamine synthesis
  a

  Adrenaline

  b

  Alanine

  c

  Cholesterol

  d

  Guanine

  e

  Tyrosine
  Explanation: Tyrosine is the starting molecule for synthesis of dopamine. Tyrosine is first converted into DOPA, which is converted to dopamine. Dopamine is broken down to noradrenaline, which can be made into adrenaline.
• 42
  What is the rationale for treatment with carbidopa in Parkinson disease?
  Difficulty: Hard     Topic: Carbidopa
  a

  Increased central L-DOPA conversion

  b

  Increase central uptake of L-DOPA

  c

  Reduce peripheral L-DOPA breakdown

  d

  Supply dopamine to the striatum

  e

  Supply dopamine to the thalamus
  Explanation: Carbidopa is a drug commonly given with L-DOPA in treatment of Parkinson disease. Carbidopa is an inhibitor of DOPA-decarboxylase, the enzyme that converts L-DOPA into dopamine. Carbidopa is unable to cross the blood brain barrier, therefore blocks peripheral L-DOPA breakdown and promotes increased central conversion of L-DOPA into dopamine. Carbidopa does not supply dopamine itself.
• 43
  What is the cause of tardive dyskinesia?
  Difficulty: Medium     Topic: Tardive dyskinesia
  a

  Acute blockade of striatal dopamine receptors

  b

  Excessive dopamine release from the substantia nigra

  c

  Increased dopaminergic receptors on the striatum

  d

  Lesion of the globus pallidus interna

  e

  Lesion of the subthalamic nucleus
  Explanation: Tardive dyskinesia is a hyperkinetic movement disorder of the head, neck and face that occurs after prolonged dopaminergic blockade. Blockade of dopamine receptors stimulates compensatory increased synthesis of receptors. Tardive dyskinesia is the effect seen by this increased density of dopamine receptors. Subthalamic nucleus lesion causes ballism - wild flailing movements.
• 44
  What are the two characteristic features of Huntington disease?
  Difficulty: Easy     Topic: Huntington disease
  a

  Bradykinesia and dementia

  b

  Bradykinesia and rigidity

  c

  Hyperkinesia and dementia

  d

  Hyperkinesia and rigidity

  e

  Hypotonia and dementia
  Explanation: Huntington disease is an autosomal dominant neurodegenerative condition characterised by hyperkinesia and early onset dementia. It is caused by damage to the indirect pathway of the basal ganglia, with consequent increased activity in the thalamo-cortical relay.
• 45
  What is the cause of cog-wheeling in Parkinson disease?
  Difficulty: Medium     Topic: Cog-wheel
  a

  Rigidity and bradykinesia

  b

  Rigidity and tremor

  c

  Spasticity and bradykinesia

  d

  Spasticity and hyperkinesia

  e

  Spasticity and tremor
  Explanation: Cog-wheeling is the clinical sign found by the combination of rigidity and resting tremor. Rigidity is one form of hypertonia, where there increased tone throughout the whole range of movement. This is in contrast to spasticity where tone is most increased at the beginning of the movement, but relaxes towards the end of movement. Spasticity is characteristic of an upper motor neurone lesion but rigidity is a feature of Parkinsonism.
• 46
  What is a seizure?
  Difficulty: Medium     Topic: Seizure
  a

  Aberrant signalling with the cortex

  b

  Clinical features of abnormal, excessive cortical excitation

  c

  Clinical manifestation of epilepsy

  d

  Excessive activation of the subcortical structures

  e

  Loss of consciousness due to excessive cortical excitation
  Explanation: A seizure is a clinical manifestation of abnormal, excessive excitation of cortical neurones. There is aberrant signalling within the cortex but the seizure is the clinical features arising from this. There are many causes of seizures (e.g. hyponatraemia, encephalitis) where epilepsy is a tendency towards unprovoked seizures. There may be subcortical activation but seizures are a manifestation of cortical activity. A seizure does not necessarily require loss of consciousness.
• 47
  What is an aura?
  Difficulty: Easy     Topic: Aura
  a

  Complex, partial seizure

  b

  Not epileptiform activity

  c

  Partial seizure with secondary generalisation

  d

  Primary generalised seizure

  e

  Simple, partial seizure
  Explanation: An aura is a simple, partial seizure. A simple seizure is one where level of consciousness is not impaired. A partial seizure is one where the activity can be localised to one hemisphere, in contrast to a generalised seizure. Partial seizures may undergo secondary generalisation for example in temporal lobe epilepsy where tonic clonic seizures are preceded by an aura.
• 48
  What is typical of patients immediately following a generalised tonic-clonic seizure?
  Difficulty: Easy     Topic: Clonic-tonic seizures
  a

  Cessation of respiratory

  b

  Increased sensory awareness

  c

  Low cardiac output

  d

  Prolonged drowsiness and confusion

  e

  Rapid recovery of consciousness
  Explanation: There are three phases to tonic-clonic seizures. First a tonic phase of generalised muscle contraction, followed by a clonic phase of symmetrical, rhythmical, rapidly alternating muscle contraction and relaxation. Finally there is a post-ictal phase where patients are very drowsy and confused, which lasts for hours but can take days to fully recover. Rapid recovery is a feature of cardiac syncope. Respirations are erratic during the seizure but there is not arrest. Cardiac output is usually maintained.
• 49
  What is the underlying pathophysiology of a generalised tonic clonic seizure?
  Difficulty: Hard     Topic: Seizure pathophysiology
  a

  Excessive basket cell activity

  b

  Inadequate basket cell activity with increased pyramidal cell activity

  c

  Increased basket cell activity with reduced pyramidal cell activity

  d

  Reduced reticular activating system excitation

  e

  Reduced thalamo-cortical relay activity
  Explanation: The most prevalent excitatory neocortical neurone is the pyramidal cell. These form many synapses with basket cells that are GABAergic and act to sample total activity in an area of neurones. It is thought that seizures arise when there is inadequate basket cell inhibition of pyramidal cells. Increased thalamo-cortical relay activity is also important, especially in absence seizures.
• 50
  What is the mechanism of action of diazepam?
  Difficulty: Easy     Topic: Diazepam
  a

  Allosteric agonist of GABA-receptors

  b

  Competitive inhibitor of GABA-A receptors

  c

  GABA-receptor agonists

  d

  Non-competitive inhibitor of GABA-receptors

  e

  Serotonin antagonist
  Explanation: Diazepam is a benzodiazepine, a class of depressant drugs that act to increase the activity of GABA-channels by binding to an allosteric site and increasing GABA transmission. They are not sufficient alone to stimulate GABA receptors, unlike barbituates, therefore do not cause life-threatening respiratory depression.
• 51
  Which anti-epileptic drug is a use-dependent sodium channel blocker?
  Difficulty: Easy     Topic: Anti-epileptic drugs 1
  a

  Ethosuximide

  b

  Levetiracetam

  c

  Lorazepam

  d

  Valproate

  e

  Vigabatrin
  Explanation: Some of the most commonly use anti-epileptic drugs are use-dependent voltage-gated sodium channel inhibitors e.g. sodium valproate, phenytoin, carbamazepine. They reduce action potentials in the cells that have a high-rate of firing due to their use-dependent nature. Ethosuximide is a calcium channel blocker. Lorazepam is a benzodiazepine. The exact mechanism of levetiracetam is unknown. Vigabatrin is a GABA-transmission enhancer.
• 52
  What is the most common side-effect of anti-epileptic drugs?
  Difficulty: Hard     Topic: Anti-epileptic drugs 2
  a

  Arrhythmias

  b

  Hepatotoxicity

  c

  Memory loss

  d

  Sedation

  e

  Seizures
  Explanation: All anti-epileptic drugs act to reduce cortical neurone activity therefore all have sedation as a side-effect to some extent. In addition there are many, potentially serious side-effects including hepatotoxicity and arrhythmias however these are specific to certain drugs and less common.
• 53
  What term is given to the loss of normal social interactions, emotion and vocabulary in schizophrenia?
  Difficulty: Easy     Topic: Schizophrenia
  a

  Broadcasting

  b

  Depression

  c

  Negative symptoms

  d

  Paranoid delusions

  e

  Pseudo-dementia
  Explanation: The features of schizophrenia are divided into positive symptoms and negative symptoms. Positive symptoms are characterised by a gain of delusions, hallucinations (e.g. broadcasting) and strange beliefs. Whereas negative symptoms are a loss of normal social interactions, language, self-care and emotions. Pseudo-dementia is depression that presents similarly to dementia.
• 54
  What does the ‘dopamine hypothesis’ pose as the cause for positive symptoms of schizophrenia?
  Difficulty: Medium     Topic: Dopamine hypothesis
  a

  Increased mesocortical pathway activity

  b

  Increased mesolimbic pathway activity

  c

  Reduced mesocortical pathway activity

  d

  Reduced mesolimbic pathway activity

  e

  Reduced nigro-striatal pathway activity
  Explanation: The dopamine hypothesis suggests that there is increased activity in the mesolimbic dopaminergic pathway, which is the origin of positive symptoms. Whilst there is reduced activity in the mesocortical pathway, which causes negative symptoms. The nigro-striatal dopaminergic pathway is needed for normal basal ganglia function and is lost in Parkinson disease.
• 55
  What hormone may be raised in patients treated with typical neuroleptics?
  Difficulty: Medium     Topic: Typical neuroleptics 1
  a

  Cortisol

  b

  Growth hormone

  c

  Oestrogen

  d

  Prolactin

  e

  Testosterone
  Explanation: Typical neuroleptics block a number of receptor sites including dopamine-1 and -2 receptors. This blockade is exerted at all sites where dopamine acts, including the pituitary. Normally prolactin release from the anterior pituitary is reduced by dopamine secreted from the hypothalamus. Inhibition of this action with typical neuroleptics may result in hyperprolactinaemia.
• 56
  What is the cause of dry mouth in patients treated with typical neuroleptics?
  Difficulty: Easy     Topic: Typical neuroleptics 2
  a

  Alpha-adrenoreceptor blockade

  b

  Dopaminergic blockade

  c

  Histamine blockade

  d

  Muscarinic blockade

  e

  Serotonergic blockade
  Explanation: Typical neuroleptics block all of the receptor sites listed above but it is the anti-muscarinic action that causes dry mouth, constipation, blurred vision and urinary retention. Alpha-adrenoreceptor block causes postural hypotension. Dopaminergic blockade has the anti-psychotic effects. Histamine block causes sedation. Serotonergic blockade may alter mood and cause appetite changes.
• 57
  What is the main benefit of atypical neuroleptics over typical neuroleptics?
  Difficulty: Easy     Topic: Atypical neuroleptics
  a

  Can be given intramuscularly

  b

  Increased dopaminergic blockade

  c

  Increased negative symptoms

  d

  Reduced extra-pyramidal side-effects

  e

  Reduced first pass metabolism
  Explanation: Atypical neuroleptics were designed with the intention of reducing the extrapyramidal side-effects that occur due to blockade of the nigro-striatal dopaminergic pathway, which predominantly uses dopamine-1 receptors. Atypicals are more selective to dopamine-2 receptors. All forms can be given intramuscularly as depot injections.
• 58
  What is the mechanism of action of naloxone?
  Difficulty: Easy     Topic: Naloxone
  a

  Agonist at GABA-receptors

  b

  Allosteric agonist at mu-receptors

  c

  Competitive antagonist at mu-receptors

  d

  Irreversible antagonist at GABA-receptors

  e

  Partial agonist at GABA-receptors
  Explanation: Naloxone is an important drug that acts as a competitive antagonist at the mu opioid receptor. It is given in opioid overdose to reverse the effects, with rapid response. However it has a short half life and due to its competitive mechanism it may be required in high doses and with repeated administrations (or continuous infusion) in some overdoses.
• 59
  Which drug is a phosphodiesterase inhibitor and adenosine antagonist?
  Difficulty: Hard     Topic: Drugs of abuse
  a

  Amphetamines

  b

  Caffeine

  c

  Cannabis

  d

  Cocaine

  e

  Ecstasy
  Explanation: Caffeine is a stimulant drug that inhibits phosphodiesterase to raise intracellular cAMP levels. It also is an adenosine-receptor antagonist, which causes vasoconstriction and rebound vasodilatation (which may result in headache). Amphetamines, cocaine and ecstasy are all sympathomimetics through slightly varying actions. Cannabis acts at specific cannabinoid receptors.
• 60
  How does water and lipid solubility affect pharmacokinetics of inhaled anaesthetics?
  Difficulty: Hard     Topic: Inhaled anaesthetics
  a

  Increased fat solubility causes more accumulation

  b

  Increased fat solubility results in less enzymatic metabolism

  c

  Increased water solubility gives slower induction

  d

  Reduced fat solubility gives a higher minimum alveolar concentration (MAC)

  e

  Reduced water solubility causes lower potency
  Explanation: For an inhaled anaesthetics to act in the cerebral grey matter they must first dissolve into blood (the gas:blood partition) then pass from blood to tissue (blood:tissue partition). Increasing fat solubility raises the amount that enters peripheral fat and accumulates during anaesthesia. There is little enzymatic breakdown of any inhaled agents. Raising water solubility increases the speed of movement through gas:water - the main determinant of induction speed. Solubility is not correlated with potency or MAC.
• 61
  What is the mechanism of action of the muscle relaxants given during general anaesthesia (e.g. atracurium)?
  Difficulty: Hard     Topic: Muscle relaxants
  a

  Competitive nicotinic antagonists

  b

  Muscarinic agonists

  c

  Nicotinic agonists

  d

  Non-competitive nicotinic antagonists

  e

  Partial agonists at nicotinic receptors
  Explanation: Muscle relaxants are usually given as an adjunct to inhaled anaesthesia to permit balance anaesthesia without need for him concentrations of anaesthetic agent. They are competitive antagonists at muscular-subtype nicotinic acetylcholine receptors, therefore will wear off. Suxamethonium is an example of a non-competitive antagonist, which is more rarely given for rapid anaesthetic induction.
• 62
  What term is given to the form of anaesthesia obtained through use of ketamine?
  Difficulty: Medium     Topic: Ketamine
  a

  Delirious anaesthesia

  b

  Dissociative anaesthesia

  c

  General anaesthesia

  d

  Surgical anaesthesia

  e

  Total analgesia
  Explanation: Ketamine is an atypical anaesthetic agent. It blocks NDMA-receptors and causes a dissociative anaesthesia where there is abolition of sensation but consciousness remains intact. Delirium is one of the stages of induction with anaesthetics. General anaesthesia implies loss of consciousness. Surgical anaesthesia requires appropriate muscle relaxation. Total analgesia does not have a specific meaning.
• 63
  Where is the crista galli located?
  Difficulty: Medium     Topic: Crista galli
  a

  Cribiform plate

  b

  Greater wing of sphenoid

  c

  Lesser wing of sphenoid

  d

  Petrous part of temporal bone

  e

  Sella turcia
  Explanation: The crista galli is a vertical projection of bone arising from the centre of a cribiform plate of the ethmoid bone, in the anterior fossa of the skull. The crista galli is an attachment for the falx cerebri. Either side of it lies the olfactory bulb (cranial nerve I) where the olfactory neurones project down through the cribiform plate.
• 64
  Which foramen transmits the ophthalmic artery?
  Difficulty: Easy     Topic: Ophthalmic artery
  a

  Foramen ovale

  b

  Foramen rotundum

  c

  Foramen spinosum

  d

  Optical canal

  e

  Superior orbital fissure
  Explanation: The ophthalmic arteries, branches of the anterior cerebral arteries, exit the skull through the optic canal along with the optic nerve (CN II). The optic canal is found underneath anterior clinoid processes, immediately lateral to the sella turcia. The superior orbital fissure transmits occulomotor, trochlear, abducens and ophthalmic division of the trigeminal nerve.
• 65
  Which intracerebral foramen lies most posteriorly in the middle cranial fossa?
  Difficulty: Hard     Topic: Middle cranial fossa
  a

  Foramen caecum

  b

  Foramen ovale

  c

  Foramen rotundum

  d

  Foramen spinosum

  e

  Superior orbital fissure
  Explanation: There are many foramen in the middle fossa of the cranial base. From anterior to posterior they are: optic canal, superior orbital fissure, rotundum, ovale, lacerum (medially) and spinosum.
• 66
  What structure passes through the foramen ovale?
  Difficulty: Medium     Topic: Foramen ovale
  a

  Internal carotid artery

  b

  Mandibular division of trigeminal nerve

  c

  Maxillary division of trigeminal nerve

  d

  Middle meningeal artery

  e

  Ophthalmic division of trigeminal nerve
  Explanation: Foramen ovale carries the Mandibular branch of the trigeminal nerve. The ophthalmic division passes through the superior orbital fissure, and the maxillary division through the foramen ovale. The internal carotid enters the skull through the foramen lacerum. The middle meningeal artery enters the skull through the foramen spinosum.
• 67
  Which bone forms the clivus in the base of the skull?
  Difficulty: Easy     Topic: Clivus
  a

  Frontal

  b

  Occipital

  c

  Parietal

  d

  Sphenoid

  e

  Temporal
  Explanation: The clivus is a flat, sloping section of bone in the posterior fossa of the cranial base - it is part of the occipital bone. The brainstem lies along the clivus along with the basilar artery and its division into the vertebral arteries.
• 68
  Which of the following structures does NOT pass through the foramen magnum?
  Difficulty: Easy     Topic: Foramen magnum
  a

  Accessory nerve

  b

  Anterior spinal artery

  c

  Hypoglossal nerve

  d

  Medulla oblongata

  e

  Vertebral arteries
  Explanation: The foramen magnum transmits the medulla oblongata along with a number of other structures. The spinal branch of the accessory nerve (CN XI) passes through. The anterior and posterior spinal arteries originate within the skull and run through the foramen as well as the vertebral arteries. The hypoglossal nerve has its own separate canal in the occipital bone.
• 69
  Which ligament is most important in preventing posterior subluxation of the odontoid process?
  Difficulty: Hard     Topic: Odontoid process
  a

  Alar ligament

  b

  Anterior longitudinal ligament

  c

  Ligament flavum

  d

  Posterior longitudinal ligament

  e

  Transverse ligament
  Explanation: There is a complex system of ligaments around C1 & C2. The odontoid peg (dens) arising from C2 lies anterior to the spinal cord and is held in place by the cruciform ligament. The transverse ligament refers to the lateral parts of the cruciform ligament that attaches to C1 and the dens. Alar ligaments connect the dens to the occipital bone. Anterior and posterior longitudinal ligaments support the spinal column. Ligamentum flavum connects adjacent vertebral laminae.
• 70
  Where does the vagus nerve exit the skull?
  Difficulty: Easy     Topic: Vagus nerve
  a

  Foramen lacerum

  b

  Foramen magnum

  c

  Hypoglossal canal

  d

  Jugular foramen

  e

  Vagal canal
  Explanation: Vagus passes through the jugular foramen along with the glossopharyngeal nerve, cranial branch of the accessory nerve and the internal jugular vein.
• 71
  Within which meningeal layer are most cerebral arterial vessels located?
  Difficulty: Easy     Topic: Cerebral arteries
  a

  Extra-dural space

  b

  Intra-dural space

  c

  Sub-arachnoid space

  d

  Sub-dural space

  e

  Sub-pial space
  Explanation: The circle of Willis and its main branches are contained within the subarachnoid space. The extra-dural space carries the meningeal vessels and emissary veins. Intra-dural space is the location for dural venous sinuses. Sub-dural space has bridging veins that pass into the venous sinuses. Sub-pial space contains small intracerebral vessels.
• 72
  What is the falx cerebri composed of?
  Difficulty: Easy     Topic: Falx cerebri
  a

  Double-layer arachnoid mater

  b

  Double-layer endosteal dura mater

  c

  Double-layer meningeal dura mater

  d

  Double-layer pia mater

  e

  Single-layer endosteal dura mater
  Explanation: There are four dural folds, which are composed of double-layered meningeal dura mater (the inner layer of dura mater). These are: falx cerebri, falx cerebelli, diaphragma sellae and tentorium cerebelli.
• 73
  What vessels are most commonly the origin of bleeding in atraumatic subdural haemorrhages?
  Difficulty: Medium     Topic: Subdural bleeds
  a

  Aponeurotic vessels

  b

  Bridging veins

  c

  Capillaries

  d

  Cerebral arteries

  e

  Meningeal arteries
  Explanation: Subdural haemorrhages may be traumatic or atraumatic and chronic. Chronic, atraumatic subdural bleeds are most commonly due to tearing of bridging veins that feed dural venous sinuses. Traumatic subdural haemorrhages may be due to tearing of larger vessels or dural sinuses. Meningeal artery bleeds are the cause of extradural haemorrhages. Subarachnoid bleeds are usually arterial and from the cerebral arteries.
• 74
  Where are ependymal cells found?
  Difficulty: Easy     Topic: Ependymal cells
  a

  Cortical white matter

  b

  In the hippocampus

  c

  Lining dural venous sinuses

  d

  Scalp periosteum

  e

  Ventricular system
  Explanation: Ependymal cells line the ventricular system and form the choroid plexus, which produces CSF. They tightly regulate the substances secreted into CSF by active processes. Most of the choroid plexus is in the lateral & 3rd ventricles but is found in all ventricles.
• 75
  Where is the foramen of Magendie located?
  Difficulty: Hard     Topic: Foramen of Magendie
  a

  Anterior to the pons

  b

  Between the lateral and 3rd ventricles

  c

  In the midbrain

  d

  Posteromedial in the 4th ventricle

  e

  Superior to the cerebellum
  Explanation: The foramen of Magendie (or median aperture) is an opening in the middle of the posterior wall of the 4th ventricle, inferior to the cerebellum. It opens into the cisterna magna, which is continuous with the subarachnoid space. The interventricular foramina is between the lateral and 3rd ventricles. The cerebral aqueduct is in the midbrain.
• 76
  Which part of the ventricular system connects the 3rd and 4th ventricles, passing through the midbrain?
  Difficulty: Medium     Topic: Ventricular system
  a

  Central canal

  b

  Cerebral aqueduct

  c

  Foramen of Lushka

  d

  Foramen of Monro

  e

  Median aperture
  Explanation: The cerebral aqueduct is a narrow channel through the midbrain that connects the 3rd & 4th ventricles. The central canal lies in the spinal cord and is an inferior continuation of the ventricular system. The foramina of Lushka are the lateral apertures of the 4th ventricle, allowing exit of CSF into the subarachnoid space. The foramen of Monro is the interventricular foramina, connecting the 3rd and lateral ventricles. The median aperture (foramen of Magendie) is in the 4th ventricle.
• 77
  Where is most CSF re-absorbed into the vascular system?
  Difficulty: Easy     Topic: CSF flow
  a

  Central canal of spinal cord

  b

  Cerebral aqueduct

  c

  Lateral apertures of 4th ventricle

  d

  Median aperture of 4th ventricle

  e

  Sagittal sinus arachnoid granulations
  Explanation: CSF is produced in the choroid plexus of the ventricular system. It descends through the ventricles and exits into the subarachnoid space, most through the apertures in the 4th ventricle. From the subarachnoid space it is reabsorbed into the vascular system through arachnoid granulations that project into dural venous sinuses.
• 78
  What structure lies immediately lateral to the 3rd ventricle?
  Difficulty: Hard     Topic: 3rd ventricle
  a

  Corpus callosum

  b

  Hippocampus

  c

  Midbrain

  d

  Pituitary

  e

  Thalamus
  Explanation: The 3rd ventricle lies between the thalamus and hypothalamus. Superior is the corpus callosum and the lateral ventricles. Inferior to the 3rd ventricle is the midbrain.
• 79
  Where is the septum pellucidum?
  Difficulty: Medium     Topic: Septum pellucidum
  a

  Attachment of the brainstem to the foramen magnum

  b

  Overlying the sella turcia

  c

  Separating the anterior and posterior fossa

  d

  Separating the cerebral hemispheres

  e

  Separating the lateral ventricle anterior horns
  Explanation: The septum pellucidum is a thin fibrous structure that lies between the two lateral ventricles. The sella turcia is covered by the diaphragma sellae. The anterior and posterior fossae are separated by the tentorium cerebelli. The cerebral hemispheres are separated by the falx cerebri.
• 80
  At what level does the common carotid artery bifurcate?
  Difficulty: Hard     Topic: Common carotid
  a

  C1/2

  b

  C2/3

  c

  C3/4

  d

  C4/5

  e

  C5/6
  Explanation: The common carotid artery bifurcates at the level of C3-4, which is approximately the level of the top of the thyroid cartilage. The internal carotid continues in the carotid sheath and passes into the carotid canal, entering the skull through the foramen lacerum. The external carotid goes on to supply the face and scalp.
• 81
  Which arteries are formed from the bifurcation of the internal carotid artery?
  Difficulty: Easy     Topic: Internal carotid
  a

  Anterior and middle cerebral

  b

  Anterior and posterior cerebral

  c

  Anterior cerebral and posterior communicating

  d

  Anterior communicating and middle cerebral

  e

  Middle and posterior cerebral
  Explanation: The internal carotid artery enters the skull through the carotid canal, then curves through the cavernous sinus and comes out the foramen lacerum. It bifurcates to form the two main vessels supplying the anterior circulation of the brain - the anterior and middle cerebral. The middle cerebral is joined by the posterior communicating artery. The anterior communicating lies between the two anterior cerebral arteries.
• 82
  Which vessel does the anterior inferior cerebellar artery branch from?
  Difficulty: Hard     Topic: Cerebellar arteries
  a

  Anterior spinal artery

  b

  Basilar artery

  c

  Pontine arteries

  d

  Superior cerebellar

  e

  Vertebral artery
  Explanation: The cerebellum is supplied by three arteries. The anterior inferior (from the basilar artery), then posterior inferior (from the vertebral arteries) and the superior cerebellar (from the basilar artery near the origin of the posterior cerebral arteries).
• 83
  Where do the posterior cerebral arteries originate from?
  Difficulty: Easy     Topic: Posterior cerebral artery
  a

  Between basilar and posterior communicating arteries

  b

  Between middle and anterior cerebral arteries

  c

  Internal carotid artery

  d

  Union of anterior choroidal arteries

  e

  Union of vertebral arteries
  Explanation: The posterior cerebral arteries are formed at the rostral end of the basilar artery, where it branches into the posterior communicating and posterior cerebral arteries. The internal carotid is between the anterior and middle cerebral arteries. The anterior choroidal arteries do not unite and are on separate sides. The basilar artery is formed by the union of the vertebral arteries.
• 84
  Which vessels supply the internal capsule?
  Difficulty: Medium     Topic: Internal capsule
  a

  Anterior cerebral arteries

  b

  Ophthalmic arteries

  c

  Pontine arteries

  d

  Posterior cerebral arteries

  e

  Striate arteries
  Explanation: The internal capsule is an important structure that contains the axons of neurones projecting towards the cerebral cortex. It is supplied by branches of the middle cerebral artery called the striate arteries, which are the most frequent source of ischaemic stroke. The strokes tend to affect one body part or one higher function only.
• 85
  Which vessel supplies the medial aspect of the parietal lobe?
  Difficulty: Easy     Topic: Parietal lobe supply
  a

  Anterior cerebral artery

  b

  Basilary artery

  c

  External carotid artery

  d

  Middle cerebral artery

  e

  Posterior cerebral artery
  Explanation: The anterior cerebral artery supplies the medial aspect of the front and parietal lobes - therefore the legs more than the upper limbs and face. It provides almost all the blood supply to the frontal lobe but not to the lateral aspect of the parietal or temporal cortex.
• 86
  Which vessel supplies the cortex responsible for motor supply to the face?
  Difficulty: Medium     Topic: Face supply
  a

  Anterior cerebral artery

  b

  Middle cerebral artery

  c

  Pontine arteries

  d

  Posterior cerebral artery

  e

  Superior cerebellar artery
  Explanation: The motor innervation to the face comes from the lateral aspect of the primary motor cortex in the frontal lobe. The middle cerebral artery provides blood supply to the lateral cortex of the frontal and parietal lobes, in addition to the entire temporal lobe. Strokes affecting the middle cerebral arteries cause symptoms in the face and upper limbs more than lower limbs.
• 87
  Which area of the brain receives dual blood supply from two separate cerebral arteries?
  Difficulty: Medium     Topic: Dual blood supply
  a

  Broca's area

  b

  Primary motor cortex

  c

  Primary visual cortex

  d

  Reticular formation

  e

  Thalamus
  Explanation: The primary visual cortex, especially the area responsible for the fovea, is supplied by both the middle and posterior cerebral arteries. Therefore, in a posterior cerebral artery stroke patients may still have some central vision preserved. Broca's area is supplied by the middle cerebral artery.
• 88
  What is the vein of Galen?
  Difficulty: Medium     Topic: Vein of Galen
  a

  Confluence of sinuses

  b

  Great cerebral vein

  c

  Inferior Sagittal sinus

  d

  Straight sinus

  e

  Superior Sagittal sinus
  Explanation: The vein of Galen is another name for the great cerebral vein, which drains blood from structures deep in the cerebral hemispheres. It joins the inferior sagittal sinus to form the straight sinus, which passes posteriorly to the confluence of sinuses.
• 89
  Which venous sinus lies immediately lateral to the pituitary gland?
  Difficulty: Easy     Topic: Venous sinuses
  a

  Cavernous sinus

  b

  Petrous sinus

  c

  Sagittal sinus

  d

  Straight sinus

  e

  Transverse sinus
  Explanation: The cavernous sinuses lie immediately lateral to the pituitary gland in the sphenoid bone. Cranial nerves III, IV, V1 and V2 run in the wall of the sinus. The internal carotid artery and cranial nerve VI run through the centre of the canal. The cavernous sinuses drain into the transverse sinus through the superior petrosal sinus; and into the sagittal sinus through the inferior petrosal sinus.
• 90
  Where is Wernicke’s area located?
  Difficulty: Easy     Topic: Wernicke's area
  a

  Deep temporal lobe

  b

  Infero-lateral frontal lobe

  c

  Insular cortex

  d

  Lateral parietal cortex

  e

  Supero-posterior temporal lobe
  Explanation: Wernicke's area is the main location for reception of language, which allows understanding and processing of its meaning. It is on the superior gyrus of the temporal lobe towards the posterior of the gyrus; it is supplied by the middle cerebral artery. The limbic system is in the deep temporal lobe. Broca's area is in infero-lateral frontal lobe. Olfactory cortex is in insular cortex.
• 91
  Which part of the basal ganglia lies medial to the internal capsule and lateral to the 3rd ventricle?
  Difficulty: Hard     Topic: Basal ganglia
  a

  Caudate nucleus

  b

  Globus pallidus

  c

  Hypothalamus

  d

  Putamen

  e

  Substantia nigra
  Explanation: The caudate nucleus lies adjacent to the 3rd ventricle, medial to the internal capsule. It is a long nucleus with a tail that extends caudally and superiorly. The globus pallidus and putamen lie immediately lateral to the internal capsule, with the putamen lying externally. The hypothalamus is not strictly part of the basal ganglia. The substantia nigra lies in the midbrain.
• 92
  Where is the sylvian fissure?
  Difficulty: Medium     Topic: Sylvian fissure
  a

  Between frontal and parietal lobes

  b

  Between frontal, parietal and temporal lobes

  c

  Between occipital lobe and cerebellum

  d

  Between parietal and occipital lobes

  e

  Between pons and cerebellum
  Explanation: The sylvian fissure (or lateral sulcus) divides the temporal lobe from the parietal and frontal lobes. The central sulcus divides the frontal and parietal lobes. The tentorium cerebelli divides the occipital lobe and cerebellum.
• 93
  What is the function of Muller’s muscle?
  Difficulty: Hard     Topic: Muller's muscle
  a

  Closes eyelid

  b

  Closes epiglottis

  c

  Raises eyelid

  d

  Tenses soft palate

  e

  Tongue protrusion
  Explanation: Muller's muscle is a smooth muscle in the upper eyelid that is innervated by sympathetic motor efferents. It has a role in keeping the eyelid open, which is correlated with sympathetic activity. Loss of sympathetic activity (e.g. Horner syndrome) causes a partial ptosis due to loss of Muller's muscle function whilst levator palpebrae superioris remains intact.
• 94
  Which cranial nerve lesion results in a medially deviated eye with diplopia on lateral gaze?
  Difficulty: Easy     Topic: Cranial nerve lesions
  a

  II

  b

  III

  c

  IV

  d

  V

  e

  VI
  Explanation: Abducens (CN VI) innervates lateral rectus, which contracts to cause lateral deviation of the eyeball. A lesion of CN VI causes a medially deviated eye with double vision when the patient attempts to look towards the side of the lesion. Optic nerve (II) lesion causes vision loss. III (occulomotor) lesion causes a 'down and out' eye. Trochlear (IV) lesions cause a failure of infero-medial movement. Trigeminal lesions cause loss of facial sensation.
• 95
  Why is an occulomotor palsy with dilated pupil a worrying clinical sign?
  Difficulty: Hard     Topic: Occulomotor palsy
  a

  May have a posterior communicating artery aneurysm

  b

  May have a thalamic tumour

  c

  Suggests intrinsic occulomotor nerve damage

  d

  Suggests raised intracranial pressure

  e

  Vision may be lost completely
  Explanation: The occulomotor nerve carries parasympathetic fibres superficially in the nerve. Therefore lesions due to physical compression cause a lesion with dilated pupil whereas intrinsic nerve damage (e.g. diabetes) is less likely to affect parasympathetic fibres. Posterior communicating artery aneurysm is a typical source of compression of CN III.
• 96
  Which cranial nerve supplies taste to the anterior 2/3rd of the tongue?
  Difficulty: Easy     Topic: Tongue supply
  a

  Facial

  b

  Glossopharyngeal

  c

  Hypoglossal

  d

  Mandibular division of trigeminal

  e

  Vagus
  Explanation: Taste to the anterior 2/3rd tongue is supplied by the facial nerve (via the chorda tympani nerve). Posterior 1/3rd taste is supplied by glossopharyngeal nerve. Hypoglossal nerve provides motor innervation to the tongue. The mandibular division of trigeminal supplies general sensation to the anterior 2/3rd of the tongue.
• 97
  Where do parasympathetic neurones supplying the lacrimal gland synapse?
  Difficulty: Easy     Topic: Lacrimal gland
  a

  Ciliary ganglion

  b

  Otic ganglion

  c

  Pterygopalatine ganglion

  d

  Submandibular ganglion

  e

  Superior cervical ganglion
  Explanation: There are four parasympathetic ganglia in the face. The ciliary ganglion for fibres to constrictor pupillae. Otic ganglion for fibres to parotid gland. Pterygopalatine ganglion for fibres to the lacrimal gland. Submandibular ganglion for fibres to the submandibular and sublingual salivary glands. The superior cervical ganglion is a sympathetic ganglion that supplies the head and face.
• 98
  What is the difference between the innervation of occipitofrontalis and the other facial muscles?
  Difficulty: Medium     Topic: Occipitofrontalis
  a

  Occipitofrontalis has bilateral upper motor neurone supply

  b

  Occipitofrontalis is supplied by CN V and CN VII

  c

  Occipitofrontalis is supplied by CN VII and C2

  d

  Other facial muscles have bilateral lower motor neurone supply

  e

  Other facial muscles have supply from CN V and CN VII
  Explanation: Occipitofrontalis receives bilateral upper (but not lower) motor neurone innervation therefore its function is preserved in stroke. This is unlike the other facial muscle that have unilateral upper and lower motor neurone innervation. However in lower motor neurone lesions of the facial nerve (e.g. Bell's palsy) there is also still loss of function in occipitofrontalis.
• 99
  What abnormality would be expected in a patient with a right sided 12th cranial nerve lesion?
  Difficulty: Medium     Topic: 12th cranial nerve
  a

  Loss of gag reflex on right

  b

  Tongue deviation to left

  c

  Tongue deviation to right

  d

  Uvula deviation to left

  e

  Weakness of neck rotation to right
  Explanation: Hypoglossal nerve (CN XII) provides motor supply to the tongue. The muscles of the tongue insert into a central tendonuous raphe; the consequence of their insertion is that in unilateral CN XII lesions the tongue deviates towards the side of the lesion. In contrast, the uvula deviates away from the side of the lesion in glossopharyngeal lesions.
• 100
  What is contained within the epidural space of the spinal canal?
  Difficulty: Easy     Topic: Epidural space
  a

  Blood

  b

  CSF

  c

  Fat

  d

  Ligamentous tissue

  e

  Tissue fluid
  Explanation: The spinal canal an area defined by the bony vertebrae, within which lies (from outside to in): epidural fat, dura mater, arachnoid mater, subarachnoid space (containing CSF), pia mater and then the spinal cord.
• 101
  In total, how many rami of spinal nerves are there?
  Difficulty: Medium     Topic: Spinal nerve rami
  a

  31

  b

  32

  c

  62

  d

  84

  e

  124
  Explanation: Each spinal cord level gives off a pair of spinal nerves, which each divided into an anterior and posterior ramus. There are 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal) and therefore 62 spinal nerves, which give 124 rami.
• 102
  What is the role of the filum terminalis?
  Difficulty: Medium     Topic: Filum terminalis
  a

  Attachment of the conus medullaris

  b

  Limit movement of the odontoid peg

  c

  Link the sympathetic chain and the spinal cord

  d

  Supply blood to the lumbar spinal cord

  e

  Support the fibres of the cauda equina
  Explanation: The filum terminalis is a thickened extension of the pia mater that attaches the conus medullaris to the posterior wall of the sacrum. The cruciform ligaments limit movement of the odontoid peg. The rami communicans link the sympathetic chain and spinal cord.
• 103
  What is the main consequence of interruption to the anterior spinal artery?
  Difficulty: Hard     Topic: Anterior spinal arteries
  a

  Loss of consciousness

  b

  Loss of motor function

  c

  Loss of proprioception

  d

  Loss of spinothalamic function

  e

  Loss of truncal balance
  Explanation: The anterior spinal artery supplies blood to the anterior 2/3rd of the spinal cord. This includes most the ventral horns and the corticospinal tracts. Consequently, interruption to this artery gives loss of motor function with relative preservation of sensory (especially dorsal column) function which is supplied by the posterior spinal arteries.
• 104
  How is potassium reabsorption altered following a 1L haemorrhage?
  Difficulty: Medium     Topic: Potassium
  a

  Aldosterone promotes high serum K+

  b

  Angiotensin-II promotes high urinary K+

  c

  Angiotensin-II promotes low serum K+

  d

  Cortisol promotes high urinary K+

  e

  Low collecting duct flow promotes K+ retention
  Explanation: Following haemorrhage there is activation of: sympathetic nervous system to increase peripheral resistance, ADH secretion and RAAS system. Aldosterone causes sodium retention and loss of potassium in the urine. Angiotensin-II increases and promotes sodium and potassium retention. Collecting duct flow will be low, which reduces potassium loss in urine.