Visual Pathways
At the optic chiasma, certain retinal fibres cross to the opposite side. Which fibres decussate at this point?
A. Temporal retinal fibres
B. Nasal retinal fibres
C. Macular fibres
D. Foveal fibres
E. Peripheral temporal fibres
B. Nasal retinal fibres
In the chiasma, fibres arising from the nasal side of each retina decussate, while temporal fibres remain uncrossed.
When light is shone into one eye, both pupils constrict. Which cranial nerve forms the afferent limb of this reflex pathway?
A. Oculomotor nerve (III)
B. Trochlear nerve (IV)
C. Abducens nerve (VI)
D. Optic nerve (II)
E. Trigeminal nerve (V)
D. Optic nerve (II)
Light stimulus travels via the optic nerve to the pretectal nuclei — the afferent limb of the reflex.
Which of the following correctly describes the primary action of the superior oblique muscle?
A. Elevation of the eye in abduction
B. Depression of the eye in adduction
C. Elevation of the eye in adduction
D. Depression of the eye in abduction
E. Intorsion of the eye in adduction
B. Depression of the eye in adduction
The superior oblique arises from the sphenoid bone, passes through the trochlea, and inserts on the superior-lateral surface of the eyeball. Its primary action is depression when the eye is adducted; it also causes intorsion and slight abduction.
Loss of consciousness during a generalised tonic–clonic seizure primarily results from:
A. Excessive stimulation of the reticular activating system
B. Transient suppression of cortical and thalamic activity
C. Decreased cerebral perfusion secondary to hypotension
D. Reduced oxygen delivery due to apnoea
E. Activation of the limbic system
B. Transient suppression of cortical and thalamic activity
During generalised seizures, widespread abnormal electrical discharges disrupt both cortical and thalamic function, impairing awareness.
A 7-year-old girl is described by her teacher as having frequent brief pauses in activity where she stares blankly and becomes unresponsive for a few seconds before resuming her work. There is no confusion afterwards. Which of the following best explains her episodes?
A. Focal impaired awareness seizures
B. Generalised absence seizures
C. Daydreaming episodes
D. Atonic seizures
E. Non-epileptic attack disorder
B. Generalised absence seizures
Brief, frequent lapses in consciousness with no post-ictal phase are characteristic of generalised absence seizures, typically seen in childhood.
A patient presents with complete vision loss in the right eye following optic nerve inflammation. Where is the lesion most likely located?
A. Optic chiasma
B. Right optic nerve
C. Right optic tract
D. Lateral geniculate nucleus
E. Right occipital cortex
B. Right optic nerve
A lesion of the optic nerve before the chiasma leads to total monocular blindness of that eye.
Which midbrain structure receives afferent fibres from the optic tract and projects bilaterally to the Edinger–Westphal nuclei to produce pupillary constriction?
A. Lateral geniculate nucleus
B. Pretectal nucleus
C. Superior colliculus
D. Ciliary ganglion
E. Frontal eye field
B. Pretectal nucleus
Fibres leave the optic tract before the lateral geniculate body and synapse in the pretectal nuclei, which stimulate both Edinger–Westphal nuclei.
During clinical examination, the patient is asked to look down and in (depression in adduction). Which muscle is primarily being tested?
A. Inferior rectus
B. Superior oblique
C. Inferior oblique
D. Superior rectus
E. Medial rectus
B. Superior oblique
Depression in adduction isolates the action of the superior oblique muscle. In contrast, depression in abduction tests the inferior rectus.
A patient collapses and is unresponsive for one minute. Witnesses report stiffening followed by jerking, tongue biting, and a short period of confusion afterwards. Which feature best supports a diagnosis of an epileptic seizure rather than syncope?
A. Sudden collapse without prodrome
B. Loss of postural tone
C. Pallor during the episode
D. Lateral tongue biting and post-ictal confusion
E. Rapid recovery to full awareness
D. Lateral tongue biting and post-ictal confusion
These are classic features of a tonic–clonic seizure; syncope typically involves brief loss of tone with rapid recovery and no confusion.
Which feature most reliably distinguishes a focal impaired awareness seizure from a generalised absence seizure?
A. Presence of automatisms
B. Altered consciousness
C. Onset in adolescence
D. Post-ictal confusion and gradual recovery
E. Brief duration (<10 seconds)
D. Post-ictal confusion and gradual recovery
Focal impaired awareness seizures have longer duration and post-ictal confusion; absence seizures are brief with immediate recovery.
A lesion of the right optic tract results in loss of the left visual hemifield from both eyes. Which of the following best describes this defect?
A. Left homonymous hemianopia
B. Right homonymous hemianopia
C. Bitemporal hemianopia
D. Binasal hemianopia
E. Central scotoma
A. Left homonymous hemianopia
Each optic tract carries fibres representing the contralateral hemifield (right tract → left field, left tract → right field).
A patient focuses on a near object. The pupils constrict, both eyes converge, and the lens becomes more convex. Which cranial nerve carries the efferent limb of this response?
A. Abducens nerve (VI)
B. Oculomotor nerve (III)
C. Trigeminal nerve (V)
D. Optic nerve (II)
E. Trochlear nerve (IV)
B. Oculomotor nerve (III)
The oculomotor nerve supplies medial rectus for convergence and parasympathetic fibres for ciliary muscle and sphincter pupillae.
When both eyes move together in the same direction (for example, both to the right), this type of movement is best described as:
A. Vergence
B. Saccadic movement
C. Version
D. Pursuit
E. Fixation
C. Version
Versions are conjugate eye movements where both eyes move in the same direction to maintain binocular alignment on a target. Vergence movements, in contrast, move the eyes in opposite directions (convergence or divergence).
Which neural network is primarily disrupted during seizures that cause impaired consciousness?
A. Corticospinal tracts controlling motor output
B. Reticular activating system and thalamocortical circuits
C. Cerebellar vermis and deep cerebellar nuclei
D. Basal ganglia motor loop
E. Limbic hippocampal pathway
B. Reticular activating system and thalamocortical circuits
Impaired consciousness in seizures occurs when abnormal electrical activity spreads to involve the thalamocortical and brainstem reticular activating systems responsible for arousal and awareness.
A patient has a generalised tonic–clonic seizure lasting 6 minutes. According to current emergency management guidelines, what should be administered first-line?
A. Intravenous phenytoin
B. Intramuscular midazolam
C. Buccal midazolam or rectal diazepam
D. Intravenous levetiracetam
E. High-flow oxygen only
C. Buccal midazolam or rectal diazepam
Status epilepticus is defined after 5 minutes of ongoing seizure activity; benzodiazepines are first-line for seizure termination.
A stroke involving the right temporal lobe damages fibres passing through Meyer’s loop. What type of visual field defect would this produce?
A. Contralateral inferior quadrantanopia
B. Contralateral superior quadrantanopia
C. Contralateral homonymous hemianopia
D. Central scotoma
E. Bitemporal hemianopia
B. Contralateral superior quadrantanopia
Fibres from the inferior retina (representing the superior visual field) pass through the temporal lobe as Meyer’s loop
Light shone into the right eye fails to constrict either pupil, but light shone into the left eye constricts both. Which structure is most likely affected?
A. Left optic nerve
B. Right optic nerve
C. Right oculomotor nerve
D. Left Edinger–Westphal nucleus
E. Right pretectal nucleus
B. Right optic nerve
Afferent defect in the right optic nerve prevents the signal reaching the pretectal nuclei, so neither pupil constricts with right-sided stimulation.
When looking up and to the left, which two muscles act as the yoke pair to produce this movement?
A. Left inferior rectus and right superior rectus
B. Left superior rectus and right inferior oblique
C. Left superior oblique and right inferior rectus
D. Left lateral rectus and right medial rectus
E. Left inferior oblique and right superior rectus
B. Left superior rectus and right inferior oblique
In levo-elevation (up and to the left), the left eye elevates via the superior rectus while the right eye elevates via the inferior oblique — these form the yoke pair for that movement.
Which of the following best describes the physiological basis of post-ictal confusion following a generalised seizure?
A. Residual muscle hypoxia after tonic contraction
B. Neuronal exhaustion and transient inhibition of cortical activity
C. Raised intracranial pressure
D. Diffuse cerebral vasoconstriction
E. Persistent epileptiform discharge
B. Neuronal exhaustion and transient inhibition of cortical activity
After a seizure, neurons enter a refractory state, producing confusion, drowsiness, and reduced responsiveness until recovery.
A 30-year-old man has a single unprovoked tonic–clonic seizure. He is advised not to drive for at least:
A. 1 month
B. 3 months
C. 6 months
D. 12 months
E. 24 months
C. 6 months
In the UK, after a first unprovoked seizure, driving is prohibited for 6 months if no underlying cause is found and no recurrence occurs.
A lesion of the left occipital cortex supplied by the posterior cerebral artery produces right homonymous hemianopia with macular sparing. Why is the macula often spared?
A. It is represented bilaterally in both visual cortices
B. It has dual blood supply from the middle and posterior cerebral arteries
C. It receives supply from the anterior choroidal artery
D. It is located anterior to the occipital pole
E. It is less sensitive to ischemia
B. It has dual blood supply from the middle and posterior cerebral arteries
The macular region of the visual cortex is perfused by both PCA and MCA, so may remain functional when PCA is occluded.
A patient presents with mild ptosis, constricted pupil (miosis), and absence of sweating on the right side of the face. This triad indicates involvement of which pathway?
A. Parasympathetic fibres of the oculomotor nerve
B. Sympathetic pathway to the eye
C. Ciliary ganglion
D. Pretectal nucleus connections
E. Corticospinal tract
B. Sympathetic pathway to the eye
Horner’s syndrome results from interruption of the sympathetic fibres from the hypothalamus to the eye, producing ipsilateral ptosis, miosis, and anhidrosis.
A patient presents with vertical diplopia that worsens when looking down and medially, such as when descending stairs. Which muscle is most likely affected?
A. Inferior oblique
B. Superior rectus
C. Superior oblique
D. Inferior rectus
E. Medial rectus
C. Superior oblique
Paralysis of the superior oblique (typically due to trochlear nerve palsy) results in vertical diplopia, particularly when looking down in adduction, as the affected eye cannot depress properly.
During a seizure, a patient becomes still, stares blankly, and makes chewing movements for about 90 seconds, followed by confusion. The seizure most likely originated in:
A. Occipital cortex
B. Frontal cortex
C. Temporal lobe
D. Parietal cortex
E. Brainstem
C. Temporal lobe
Focal seizures with impaired awareness commonly arise from the temporal lobe and feature automatisms such as lip-smacking and altered awareness.
A 27-year-old woman is newly diagnosed with generalised tonic–clonic seizures. She is sexually active and not using reliable contraception. According to NICE guidance, which antiepileptic drug should not be initiated in this patient?
A. Carbamazepine
B. Levetiracetam
C. Lamotrigine
D. Sodium valproate
E. Topiramate
D. Sodium valproate
NICE NG217 (2025) recommends that sodium valproate must not be initiated in women of childbearing potential unless other options are ineffective or not tolerated, due to the high risk of teratogenicity and neurodevelopmental disorders in exposed pregnancies.