Muscle Weakness Flashcards
If a patient presents with hyper acute symptoms that occurred over seconds to minutes, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
1 - Vascular
If a patient presents with acute symptoms that occurred over hours, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
2 - Vascular / inflammatory
If a patient presents with sub-acute symptoms that occurred over days to weeks, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
3 - Inflammatory / Metabolic
If a patient presents with chronic symptoms that occurred over months to years, which 2 of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
4 - Neoplastic*
5 - Degenerative
If a patient presents with acute on chronic symptoms that worsened an existing condition, which of the following is this MOST likely to be?
1 - Vascular
2 - Vascular / inflammatory
3 - Inflammatory / Metabolic
4 - Neoplastic*
5 - Degenerative
6 - Metabolic
6 - Metabolic
The descending tracts are important pathways, what are they though?
1 - transmit information about pain
2 - transmit information relating to proprioception and fine touch
3 - transmit information relating initiate movements from upper to lower motor neurons
4 - all of the above
3 - transmit information relating initiate movements from upper to lower motor neurons
The descending tracts are important pathways for motor function. Which 2 of the following are the 2 groups they can be separated into?
1 - Voluntary control of movement = pyramidal/corticospinal tract
2 - Involuntary control of movement = Extrapyramidal tracts (4 in total)
3 - Cerebrospinal track - unconscious movements
4 - Spinothalamic tract = pain and sensation
1 - Voluntary control of movement = pyramidal/corticospinal tract
2 - Involuntary control of movement = Extrapyramidal tracts (4 in total)
The descending corticospinal tract is a 2 neuron circuit. Where does the 1st order neuron begin?
1 - cell body in the cerebellum
2 - cell body in the cerebral cortex
3 - cell body in the posterior parietal lobe
4 - cell body in the pyramids
2 - cell body in the cerebral cortex
- passes through corona radiata, internal capsule (both white matter pathways, located between the thalamus and the basal ganglia)
The descending corticospinal tract is a 2 neuron circuit. Where does the 1st order neuron end?
- enter brain stem
- 80% decussate in the medulla
- 20% do not decussate in the medulla and remain
Once the upper neuron (1st order) in descending corticospinal tract (CST) reaches the order in the spine where to which the nerves innervate the body, where does the 80% of fibres that decussated at the pyramids enter the spinal cord?
1 - lateral fasciculus and into the lateral ventral horn
2 - anterior fasciculus and then into the ventral horn
3 - substantia gelatinosa
4 - lateral gentate and anterior spinal nerve
1 - lateral fasciculus and into the lateral ventral horn = 80% that decisated at medulla
2 - anterior fasciculus and then into the ventral horn = 20% that did not decusate at medulla
- here they BOTH innervate alpha and gamma motor neurons
Once the upper neuron (1st order) in descending corticospinal tract (CST) reaches the order in the spine where to which the nerves innervate the body, they will enter the lateral (80% of CST) or anterior (20% of CST) fasciculus and then into the ventral horn of the spinal cord. What do they synapse with here?
- lower motor (2nd order) neuron
- alpha and gamma motor neurons
- this neuron will then innervate target tissues
Match where the alpha and gamma motor neurons innervate?
- extrafusal = muscle shortening (contract)
- intrafusal = muscle spindles (proprioceptive)
1 - alpha = extrafusal muscle
2 -gamma =intrafusal muscle
Where can alpha (voluntary movement) and gamma (muscle spindles) neurons be located in the spinal cord as part of the descending corticospinal tract?
- located in the grey matter
- trunk, limbs, flexor and extensor muscles are all located in different regions
If there is a lesion in the descending corticospinal tract that originates above or below the medualla oblongata will the symptoms present on the same or opposite side of the body?
- above medulla = contralateral (opposite) side of the body
- below medulla = ipsilateral side (same side) of the body
The pyramidal/corticospinal tracts is the descending tract that controls conscious fine conscious motor movement. Why is it called the pyramidal/corticospinal tract?
- decussates at the pyramids in the medulla oblongata
- originates in the pyramidal cells of the primary motor cortex
The corticospinal tract is the pyramidal tract which leaves the cortex, decussates at the pyramids (80% do and 20% do not decussate) and travels in the lateral and anterior fasciculus, before synapsing in the ventral horn. Of the 80 and 20% that do and do not decussate, what parts of the the body do they innervate?
- 80% that decussates travel in lateral fasciculus and innervate the distal muscles for fine motor movements
- 20% that do not decussates travel in anterior fasciculus and innervate the axial muscles for fine large movements
The corticospinal tract is the main descending motor control tract in the nervous system. This system connects the motor cortex with where?
1 - posterior (dorsal) horn
2 - lateral horn
3 - anterior (ventral) horn
4 - target tissue
3 - anterior (ventral) horn
The corticospinal tract is the main descending motor control tract in the nervous system. Which motor neurons does the corticospinal tract communicate with?
1 - gamma motor neurons
2 - alpha motor neurons
3 - delta motor neurons
4 - y motor neurons
2 - alpha motor neurons
- innervate the contractile fibres that shorten called extrafusal fibres
If a patient has an upper motor neuron lesion, it could be in all of the following locations, EXCEPT where?
1 - primary motor cortex in frontal lobe
2 - cerebellum
3 - brainstem (midbrain, pons, medulla)
4 - spinal cord
5 - anterior horn of spinal cord
2 - cerebellum
- everything else is classed as an upper motor neuron
Which 2 of the following are commonly observed in patients who have a lesion in the corticospinal tract?
1 - excessive elbow extension
2 - excessive elbow flexion
3 - excessive knee flexion
4 - excessive knee extension
2 - excessive elbow flexion
4 - excessive knee extension
- suspected to be evolution allowing us to still eat whilst stabilising ourselves in upper motor neuron pathologies
In upper motor neuron lesions, which can occur anywhere in the image we can get a reduction in muscle mass. Why does this occur?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei
3 - increased afferent (Away from muscle) pathway activity
4 - reduced innervation of the alpha motor neurons
1 - cortex to muscle is lost so no innervation and atrophy occurs
- aprox 15-20% loss
- in lower motor neuron lesions there is a greater loss in muscle mass
- often called denervation atrophy
- aprox 65-70% loss
The medullary reticulospinal tract that begins in the medulla is a descending tract. What is the function of this tract?
1 - extensor muscle control
2 - flexor muscle control
3 - flexor and extensor muscle control
4 - inhibition of all ascending tract
2 - flexor muscle control
In upper motor neuron lesions, which can occur anywhere in the image we can get a increase in muscle tone called hypertonia. Why does this occur?
1 - cortex to muscle is lost so no innervation and atrophy occurs
2 - loss of inhibition from the medullary reticulospinal nuclei (MRN)
3 - increased afferent (Away from muscle) pathway activity
4 - reduced innervation of the alpha motor neurons
2 - loss of inhibition from the medullary reticulospinal nuclei (MRN)
- some fibres from the corticospinal tract branch off and innervate the MRN
- the MRN then travels to the anterior horn and inhibits/fine tunes muscle contractions of alpha motor neurons
- loss of this means alpha motor neurons fire too much, hence the increased tone