All lectures Flashcards
What is the neural tube made up of at 4 weeks?
1) Prosencephalon
• Telencephalon
• Diencephalon
2) Mesencephalon
3) Rhombencephalon
• Metencephalon
• Myencephalon
When are all neurones born by?
12 weeks
What is the main input and output layer for the cerebral cortex?
Input
• Inner granular cell layer
Output
• Inner pyramidal cell layer
What are the types of cortex, based on layers
1 layer: paleocortex
3 layers: archicortex
6 layers: neocortex
What are the types of receptor, their fibre types and what they are sensitive to?
Which are rapid-adapting and which are slow-adapting receptors?
Hair follicle receptor - Both • Direction • II, Aβ Meissner corpuscle - Rapid-adapting • 5-40Hz • II, Aβ Pacinian corpuscle - Rapid-adapting • 60-300 Hz • II, Aβ Merkel cell - Slow-adapting • Touch, pressure • II, Aβ Raffini corpuscle - Slow-adapting • Stretch • II, Aβ Free nerves • Pain • IV, C Aδ
What are the signs of sensory ataxia?
- Loss of two-touch discrimination
- Romberg’s sign
- Broad stamping gait
Where does the following travel?
1) Contralateral unconscious proprioception
2) Ipsilateral unconscious proprioception
1) Anterior spinocerebellar tract
2) Posterior spinocerebellar tract
What are the Brodman’s areas of the postcentral gyrus all responsible for?
1 = Cutaneous stimulus 2 = Tactile, shape identification 3a = Proprioception 3b = Primary somatosensory cortex
Give the receptors for each fibre type on the roman numeral system.
Ia - Muscle spindle primary ending Ib - Golgi tendon organ II - Muscle spindle secondary ending, kinesthesia III - Pain, temp, crude touch IV - Pain, temp, fine touch
Which extrapyrimidal tracts do and do not decussate?
DO:
• Tectospinal
• Rubrospinal
DO NOT:
• Vestibulospinal
• Pontine reticulospinal
BOTH:
• Medullary reticulospinal
Decerebrate posturing and decorticate posturing
Decerebrate
• Lesion below or at red nucleus
• Loss of red nucleus function
• Extensor dominance
Decorticate
• Lesion above red nucleus
• Disinhibition of red nucleus
• Flexor dominance
How is acetylcholine made?
Acetyl-CoA + Choline —choline acetyltransferase–> Acetylcholine
What are the three types of motor units
Type I - slow twitch
• Slow
• Fatigue resistant
Type IIa - Intermediate
• Fast
• Fatigue resistant
Type IIb - fast
• Fastest
• Fatiguable
LMN damage causes…?
- Flaccid paralysis
- Fasciculations and fibrillations
- Complete loss of reflexesg
For both the pontine and the medullary reticulospinal tracts, state the following:
1) Which descending pathway the fibres run in
2) If they are ipsilateral or contralateral
3) Their function
Pontine:
1) Medial reticulospinal tract
2) Ipsilateral
3) Control of reflexes & EXTENSOR LMNs
Medullary
1) Lateral reticulospinal pathway
2) Both ipsilateral and contralateral
3) Initiation of patterned movements & FLEXOR LMNs
NB: paramedian midbrain reticular formation contains planning INFORMATION for walking, medullary RF just initiates it.
