pathophysiology of the motor system Flashcards
what are the symptoms of a frontal lobe lesion
-Difficulty with executive functions: hard to manage his daily plans, decision-making problem, not organized…etc.
-Change in personality and behavior: more aggressive, less compassion, social isolation…etc.
upper motor neuron lesion (site of lesion, m. weakness, m. tone, m. atrophy, fasciculation, tendon reflex, plantar reflex)
-site of lesion: cortex, brainstem, spinal cord
-m. weakness: yes (plegia)
-m. tone: increased (spasticity)
-m. atrophy: disuse atrophy
-fasciculation: no fasciculations
-tendon reflex: hyperreflexia
-plantar reflex: positive babinski sign
lower motor neuron lesion (site of lesion, m. weakness, m. tone, m. atrophy, fasciculation, tendon reflex, plantar reflex)
-site of lesion: ant horn, roots, nerves, neuromuscular junction
-m. weakness: yes (myopathy)
-m. tone: decreased (hypotonia)
-m. atrophy: denervation atrophy
-fasciculation: fasciculations
-tendon reflex: hyporeflexia
-plantar reflex: negative babinski sign
what kind of lesion causes hyporeflexia: absence or weak extension of the leg
lower motor neuron lesion
what kind of lesion causes hyperreflexia: strong extension of the leg
upper motor neuron lesion
upper motor neuron lesion causes _____ on the reflex circuit
lack of control
what does the distribution of facial weakness provide
important localizing clues indicating whether the underlying injury involves the lower motor neuron (LMN) or the upper motor neuron (UMN)
injury to the primary motor cortex causes a weakness of what facial m.
what input is lost and intact
contralateral inferior facial muscles:
Ø Input to inferior facial muscles from the UMN in primary motor cortex is lost.
Ø Input to superior facial muscles from the UNM in the premotor areas (cingulate gyrus) remains intact.
injury to the corticobulbar tract causes a weakness of what facial m.
what input is lost and intact
contralateral inferior facial muscles:
Ø Input to inferior facial muscles from the UMN in primary motor cortex is lost.
Ø Input to superior facial muscles from the UNM in the premotor areas (cingulate gyrus) remains intact bc this input projects bilaterally
injury to the facial motor nucleus or its n. causes a weakness of what facial m.
what input is lost and intact
all m. of facial expression on the same side of the lesion:
Ø Input to inferior and superior facial muscles from the LMN is lost.
what is aphasia
Aphasia is a disorder in the comprehension and/or expression of language
what are the 2 diff types of aphasia
-Broca’s (motor) aphasia: loss of the ability to produce language.
-Wernicke’s aphasia: difficulty understanding speech.
why is broca’s aphasia also called non-fluent aphasia
Characterized by the loss of the ability to produce language,
why is broca’s aphasia also called motor aphasia
Lesion in the Broca’s area: the posterior inferior frontal gyrus (inferior part of the motor cortex)
what is broca’s aphasia mostly caused by
stroke
what does the severity of broca’s aphasia varies from and what does it depend on
The severity of the problem varies from the complete loss of the ability to speak to struggle to speak depends on the size of the affected area.
is there a possibility of recovery w broca’s aphasia
yes, Possibility of recovery by speech therapy.
what is multiple sclerosis
an immune-mediated inflammatory disease that causes the demyelination of the nerves of central nervous system
what happens w multiple sclerosis when it affects motor neurons, sensory neurons or optic fibers
motor neurons: m. weakness
sensory neurons: loss of sensation
optic fibers: visual disturbances
what is myasthenia gravis
a neuromuscular disease that causes weakness in the muscles (e.g. drooping of eyelids, difficulty swallowing, shortness of breath)
what happens with myasthenia gravis
-Acetylcholine (Ach) receptors blocked (or destroyed) by antibodies (autoimmune disease).
-Reduced transmission of Ach in the muscle.
-Impaired muscle contraction.
what is the treatment for myasthenia gravis
Cholinesterase inhibitors: inhibit the metabolism of Ach by the cholinesterase enzyme (i.e., keep more Ach in the synaptic cleft), Thus, boost signals between nerves and muscles to improve muscle strength
parkinson’s disease is the degeneration of what neurons
substantia nigra’s neurons (loss of dopaminergic neurons)
what does parkinson’s cause
igidity, tremor and akinesia (i.e. inability to initiate and stop movement)
