Neuro Flashcards
What does the cortico-spinal tract innervate? What is its tract?
Cortico-spinal tracts are motor pathways.
80% to skeletal muscles in the proximal parts of the limb. Lateral cortico-spinal path; decussation at the medulla.
20% to skeletal muscles in the distal parts of the limbs and trunk. Anterior cortico-spinal tract. No decussation
What does the rubrospinal tract innervate? What is its tract?
Controls muscle tone in flexion. Originates in the red nucleus (in the rostral midbrain), then decussates at the ventral tegmental area, descends laterally as rubrospinal and rubroreticular tracts, splits at medulla with the rubrospinal tract going through the lateral reticular nucleus, before ending at the spinal cord.
What is the dorsal column system? What sensations does it supply/innervate?
Dorsal column system sends sensory information on light touch, fine discriminative touch, two-point discrimination and vibration to the somatosensory cortex of the brain.
- Tracts synapse at the medulla. Those below T6 synapse at the nucleus gracilis whereas those above T6 synapse at the nucleus cuneatus.
- Ascend upwards and decussates at the caudal medulla (lower medulla) via the contralateral medial lemniscus tract. 1st order neurons end here.
- Axons terminate at the ventral posterior lateral nucleus (VPL) of the thalamus. 2nd order neurons end here.
- Neurons from VPL project to somatosensory cortex. 3rd order neurons end here.
What is the spinothalamic system? What sensations does it supply/innervate?
The spinothalamic system sends sensory information on crude touch (anterior) and pain & temperature (lateral).
1. 1st order neurons terminate at the dorsal horn.
2. 2nd order neurons decussate immediate upon reaching the spinal cord.
3.
What are the main causes of a coma?
Diffuse intracranial - Brain injury, Subarachnoid haemorrhage, Meningitis, Encephalitis, Epilepsy
Hemisphere lesion - Subdural & extradural haemorrhage, abscess, tumour, cerebral infarct
Brain stem - cerebellar haemorrhage, cerebellar infarct, brainstem infarct, abscess, tumour
Metabolic - drug overdose, diabetes, hypoglycaemia, hypercalcaemia, “the failures”
Which one of these would you expect a patient with Brown-Sequard Syndrome resulting from a lesion at the level of T9 to have?
Contralateral hemiparesis
Loss of contralateral spinothalamic sensation below L1
Contralateral loss of regular touch sensation
Loss of contralateral spinothalamic sensation below the level of T9 with normal sensation preserved above
Loss of contralateral spinothalamic sensation below L1.
The neurons involved in the spinothalamic pathways ascend for between 2-4 segments before crossing over to the opposite side of the spinal cord.
Match the terms with their causes
*Terms* Brain stem death Normal consciousness Locked in syndrome Vegetative state
*Causes* Irremedial damage to the hindbrain Damage to ventral pons with intact cortex and reticular activating system Diffuse destruction of cerebral cortex Intact reticular activating system
Brain stem death - Irremedial damage to the hindbrain
Vegetative state - Diffuse destruction of the cerebral cortex
Locked-in syndrome - Damage to ventral pons with intact cortex and reticular activating system
Normal consciousness - intact reticular activating system
Which of the following might a person with classical complete Locked-in Syndrome be able to communicate with? Pick one or more than one.
Vertical eye movements Tongue movements Blinking Horizontal eye movements Raising a finger
Vertical eye movements
Blinking
Vertical eye movements are controlled by the abducens nerve (CN 6). True or false?
False. The abducens nerve abducts an eye. The occulomotor nerve is responsible for vertical eye movements.
What are the functions of the different eye muscles? Superior oblique Inferior oblique Medial rectus Lateral rectus Superior rectus Inferior rectus
Superior oblique - Abduction, depression, medial rotation
Inferior oblique - Adduction, elevation, lateral rotation
Superior rectus - Elevation, adduction and medial rotation
Inferior rectus - Depression, adduction, lateral rotation
Medial rectus - adduction
Lateral rectus - abduction
What are the cranial nerves innervating the extrinsic muscles of the eye?
Superior rectus - CN3 Occulomotor Lateral rectus - CN6 Abducens Inferior rectus - CN3 Trochlear Inferior oblique - CN3 Occulomotor Medial rectus - CN3 Occulomotor Superior oblique - CN4 Trochlear
Link the condition with the corresponding possible motor function.
*Condition* Coma Vegetative state Minimally conscious state Locked-in syndrome
Motor function
Quadripelgic
Occasional non-purposeful movement. Withdraws to noxious stimuli.
Reaches for objects, localises noxious stimuli.
Reflex and postural responses only.
Coma - Reflex and postural responses only.
Vegetative state - Occasional non-purposeful movement. Withdraws to noxious stimuli.
Minimally conscious state - reaches for objects, localises noxious stimuli
Locked-in syndrome - Quadripelgic
Seizures are specific to epilepsy. True or false?
False.
Link these observations of seizures with their type of seizure.
Observation
Focal motor or sensory symptoms, no loss of consciousness
5-15 seconds of vacancy, sometimes myoclonic jerks
Loss of consciousness followed by a stiff body with flexed elbows and extended legs followed by violent shaking with eyes rolling
Deja-vu, depersonalisation, strange tastes or smells, altered emotion, epigastric fullness
*Type of seizure* Tonic-clonic Simple partial Absence Complex partial
Focal motor or sensory symptoms, no loss of consciousness - simple partial
5-15 seconds of vacancy, sometimes myoclonic jerks - absence seizure
Loss of consciousness followed by a stiff body with flexed elbows and extended legs followed by violent shaking with eyes rolling - Tonic-clonic
Deja-vu, depersonalisation, strange tastes or smells, altered emotion, epigastric fullness - Complex partial
An aura is experienced at the end of an attack and may help to localise the site of the seizure. True or false?
False. Whilst an aura may indeed help to localise the seizure within the brain, an aura precedes and marks the onset of an attack. Additionally, a prodrome refers to behavioural or mood changes which may precede an attack by many hours.
