Neurology Flashcards
What are the three primary brain vesicles?
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
What are the five secondary brain vesicles?
Telencephalon, diencephalon (forebrain)
Mesencephalon (midbrain)
Metencephalon, myelencephalon (hindbrain)
What is the brainstem made up of?
Midbrain, pons and medulla oblongata
What are the two main cell types in the CNS?
Neurons and glial cells
What are the 4 types of glial cells?
Astrocytes, oligodendrocytes, microglia and ependymal cells
Which glial cells function as support cells, maintaining the blood-brain barrier and in environmental homeostasis?
Astrocytes
Which glial cells are responsible for producing myelin in the CNS?
Oligodendrocytes
Which glial cells are responsible for antigen-presenting in the CNS?
Microglia
Which glial cells line the ventricles?
Ependymal cells
What is white matter in the brain made up of?
Axons (mostly myelinated) and their support cells
What is grey matter in the brain made up of?
Huge numbers of neurons, cells processes, synapses and support cells
What is the lentiform nucleus made up of?
Putamen and globus pallidus
How many paired spinal nerves are in the spinal cord?
31 paired spinal nerves
C1-8 T1-12 L1-5 S1-5 Coccygeal
Where do the spinal nerve roots pass until they reach the appropriate intervertebral foramina?
Subarachnoid space
The spinal cord terminates in a tapered cone shape… what is this called?
Conus medullaris
What is the name of the thin connective tissue cord which connects the conus medullaris to the dorsum of the coccyx?
Filum terminale
What are the four somatic senses?
Touch, proprioception, pain and temperature
What are the three types of somatosensory fibres?
Non-myelinated (type C), small (type A-δ) and large (type A-α or A-β)
Which somatosensory fibres are the slowest and senses burning pain and hot temperatures?
Non-myelinated fibres (type C)
Which somatosensory fibres sense sharp pain, cold temperature and gross touch?
Small myelinated fibres (type A-δ)
Which somatosensory fibres are the fastest and sense proprioception, vibration and fine touch?
Large myelinated fibres (type A-α or A-β)
Where is the primary sensory cortex located?
Parietal lobe of the brain
What are the two somatosensory pathways?
Medial lemniscal pathway (posterior) and spinothalamic pathway (anterior)
What information does the medial lemniscal pathway carry?
Fine touch, vibration and proprioception
What type of somatosensory fibre make up the first-order neuron of the medial lemniscal pathway?
Large myelinated fibres (type A-α or A-β)
What part of the spinal cord do the first-order neurons of the medial lemniscal pathway run through?
Posterior funiculus
- cuneate fascicle for upper body
- gracilis fascicle for lower body
Where does the first synapse of the medial lemniscal pathway occur?
Medulla
Where does the medial lemniscal pathway decussate?
Medulla
Where does the second synapse of the medial lemniscal pathway occur?
Thalamus
Where does the third synapse of the medial lemniscal pathway occur?
Sensory cortex of parietal lobe
What information does the spinothalamic pathway carry?
Pain, temperature and crude touch
What type of somatosensory fibres make up the first-order neuron of the spinothalamic pathway?
Small myelinated (sharp pain, cold temperature) and non-myelinated (hot temperature, burning pain and crude touch)
Where does the first synapse of the spinothalamic pathway occur?
Posterior horn of the spinal cord
Where does the spinothalamic pathway decussate?
In the spinal cord - two vertebral segments above where it entered
After spinothalamic fibres decussate in the spinal cord, neurons are then carried through one of two tracts to the thalamus. What are these tracts?
Lateral tract (carries information for pain, pressure and temperature through lateral funiculus)
Anterior tract (carries information for crude touch through anterior funicular)
Where does the second synapse of the spinothalamic pathway occur?
Thalamus
Where does the third synapse of the spinothalamic pathway occur?
Sensory cortex of the parietal lobe
Where is the primary motor cortex located?
Frontal lobe of the brain (along the precentral gyrus)
What are the two pyramidal tracts and their functions?
Corticospinal tract - forms efferent nerve fibres of UMNs to conduct impulses from brain to spinal cord
Corticobulbar tract - conducts impulses from brain to cranial nerves
Where does the corticospinal tract decussate?
85% at medulla to form lateral corticospinal tract.
Remaining 15% become the anterior corticospinal tract which decussates further down the spinal cord.
What part of the body does the lateral corticospinal tract control?
Muscles of limbs
What part of the body does the anterior corticospinal tract control?
Muscles of trunk
What tracts make up the extra-pyramidal system?
Tectospinal, reticulospinal and vestibulospinal
What is the function of the tectospinal tract?
Though to mediate reflex head and neck movement to visual/auditory stimuli
What is the function of the reticulospinal tract?
Coordinates automatic locomotion, posture movement and voluntary movement
Has two parts, pons and medulla, with opposing actions on extensor and flexor movement
What is the function of the vestibulospinal tract?
Maintains upright balance and posture through action on muscles of trunk and legs
Spinal cord hemisection results in paralysis on the same side and loss of sensation on the opposite side. What is this called?
Brown-Sequard Syndrome
What are the functions of the cerebellum?
Coordination movement, controlling posture, balance and fine motor movement, and for motor learning
What is the name of the fibrous membrane separating the brain from the cerebellum?
Tentorium cerebelli (fold of dura mater)
What is the name of the narrow ridge separating the cerebellar hemispheres?
Vermis
What are the three layers of the cerebellar cortex?
Molecular layer (outer)
Purkinje cell layer (middle)
Granular cell layer (inner)
What is deep to the cerebellar cortex?
White matter AKA arbor vitae
What are the four pairs of deep cerebellar nuclei located deep within the white matter?
Lateral to medial
- dentate nucleus
- interposed nuclei (globose and emboliform nuclei)
- fastigial nucleus
Where does input to the cerebellum arrive?
Cerebellar peduncles and then project mainly to the granular cell layer
What attaches the cerebellum to the brainstem?
A stalk of tissue divided into three parts: superior, middle and inferior peduncles
What are the three lobes of the cerebellum?
Anterior, posterior, flocculonodular lobes
Where does the output from the cerebellum originate from?
Axons from Purkinje cells
Where do axons from Purkinje cell layer in the cerebellum synapse?
Neurons of the deep cerebellar nuclei
Where do the neurons of the deep cerebellar nuclei synapse?
Most cross the midline and synapse in the thalamus, which in turn sends fibres to the motor cortex
What are the three functional divisions of the cerebellum and their functions?
Cerebrocerebellum/pontocerebellum - largest division formed of lateral hemispheres, involved in planning movements/motor learning
Spinocerebellum - consists of the vermis and intermediate part of hemispheres, receives input from spinal cord about proprioception and aids regulation of movement
Vestibulocerebellum - consists of the flocculonodular lobe and immediately adjacent vermis, receives vestibular input about balance and eye movement
Do cerebellar hemispheres influence the ipsilateral or contralateral side of the body?
Ipsilateral
How will a unilateral hemispheric lesion of the cerebellum present?
Ipsilateral disturbance of limb coordination and can result in an intention tremor and unsteady gait in absence of weakness or sensory loss
How will a bilateral hemispheric lesion of the cerebellum present?
Slowed, slurred speech (dysarthria), bilateral incoordination of the arms and a staggering, wide-based gait (cerebellar ataxia)
How will a midline lesion of the cerebellum present?
Disturbance of postural control - patient will tend to fall over from standing or sitting despite preserved limb coordination
How does acute alcohol exposure affect the cerebellum?
It will typically result in bilateral cerebellar hemisphere dysfunction and presents with cerebellar ataxia
