Lecture 11: Motor Systems Flashcards
(46 cards)
If a pt moves his hand down and back indicating he cannot perform the motor sequence although he knows the position of the limb, this is called ____________. If he raises his left hand and assures you that its his right, this right-eft disorientation is called ____________
Apraxia; agnosia
**With agnosia they can do the movement but doesnt know the difference, however they will pick up a pencil with their dominant hand -> this is an automatic-voluntary dissociation
The ___________ lobe incorporates motivation and memory. A pt who has a disturbance of the ___________ lobe is often apathetic and difficult or impossible to test for any cognitive activity
Prefontal lobe; frontal lobe
**A pt has the inability to demonstrate how to produce a voluntary cough. This iscalled: A. Agnosia B. Agraphia C. Apraxia D. A phobia E. Automatic-voluntary dissociation
C. Apraxia
About 40-60% of the corticospinal fibers originate from the _______________ cortex. This area controls precise and individual movements of the digits and distal extremities. The _____________ cortex is located anterior to the precentral gyrus and includes Broca’s speech area and the frontal eye field
Primary motor cortex; premotor cortex
**Premotor and supplementary cortices are involved in ideation and programming of movements
How does the premotor cortex receive input from the cerebellum?
Ventral anterior nucleus of the thalamus
Where do corticospinal and corticobulbar tracts arise?
From large pyramidally shaped neurons -> cells of Betz located in primary motor and premotor cortices
These fibers descend from these areas as part of the corticorubrospinal and corticoreticulospinal pathways, respectively
Explain the corticospinal tract up to the point of decussation
Descends through the corona radiata, internal capsule, cerebral peduncles, pons and upper medulla -> in the lower medulla, the majority of the fibers decussate at the pyramidal decussation and form the lateral corticospinal tract -> remaining uncrossed fibers continue as the anterior corticospinal tract
Where do upper extremety motor fibers of the CST versus lower extremity motor fibers decussate?
UE decussate more superior and medial compared to the more inferior and lateral decussation of the LE at the lower boundary of the cervicomedullary jnx
UE CST fibers assume a medial position in LCST
LE assume a more lateral position
What does a espionage of the upper portion of the pyramidal decussation result in?
Paralysis of UE without LE involvement -> referred to as bell’s cruciate paralysis
Where do direct versus indirect corticobulbar fibersterminate?
Direct terminate directly upon LMNs of the trigeminal, facial and hypoglossal motor nuclei
Indirect terminate in the reticular formation surrounding the brainstem motor nuclei
Where do direct corticobulbar fibers decussate?
Lower pons between the levels of entrance of the trigeminal and abducens nerves
What is the function of indirect corticobulbar fibers?
Play a role in recovery from lesions involving the direct corticobulbar fibers and have a role in physical therapy
What is the cause of supranuclear facial palsy?
Unilateral lesions of the corticobulbar fibers above the level of the facial nucleus
What are the symptoms of supranuclear facial palsy?
The contralateral mimetic muscles on the lower quadrant of the face are paralyzed
Upper quadrant facial muscles are unaffected by unilateral lesions of the corticobulbar fibers due to bilateral innervation of the facial nucleus
How do the lesions causing supranuclear facial palsy versus bell’s palsy differ?
Most common sites for lesions causing supranuclear facial palsy = facial region of motor cortex and genu of internal capsule
Bell’s palsy = central lesion of facial nerve
What are the symptoms of Bell’s palsy?
Ipsilateral paralysis of the mimetic muscles
What does the basal ganglia include?
Globus pallidus Caudate nucleus Putamen SUbstantia Nigra Red nucleus Subthalamus Nucleus accumbens
What is the paleostriatum?
Same thing as the globus pallidus
What structures comprise the striatum (neostriatum)?
Caudate
Putamen
Nucleus accumbens
What structures comprise the corpus striatum?
Globus pallidus
Caudate nucleus
Putamen
What structures comprise the enticular nucleus?
Globus pallidus
Putamen
What structures comprise the dorsal striatum?
Caudate nucleus
Putamen
In what part of the brain is the globus pallidus in and what is it one of the principal sources of?
Its part of the diencephalon
One of the principle sources of efferents from the basal ganglia
Where is the caudate nucleus located and what is it functionally similar to in its connections?
Located on surface of inner curvature of lateral ventricle
Functionally similar to putamen
