T7.3 Organization of the Motor System Flashcards
The lateral and anterior portion of the ventral horn of C5-T1 is injured what is most likely lost.
A. Extensor digiti minimi
B. Bicep Brachii
C. Tricep Brachii
D. Flexor digitorum
RFA
Ans. A. Extensor digiti minimi- is the most distal extensor listed. Anterior portion of the ventral horn is extensor (posterior is flexors), lateral portion is distal (medial is proximal)
B. Bicep Brachii- Proximal flexor
C. Tricep Brachii- Proximal extensor
D. Flexor Digitorum- Distal Flexor
A patient comes into the clinic he has been “feeling weird” after falling on his back. It is found that he a herniated disk that is impinging on the anterior spinal artery. Which symptom is most likely?
A. unilateral loss of proprioception
B. unilateral plantar response
C. Bilateral loss of temperature sensation
D. bilateral loss of sense of vibration
RFA
Ans. C.- the patient is suffering from anterior spinal artery syndrome which is related to Bilateral loss of pain and temp. as well as: * Paraperies * Bilateral extensor plantars response *Sexual function impaired
But there is no loss of touch, vibration, proprioception since those go through the dorsal tract.
Which pathway powerfully suppresses extensor spinal reflex activity?
A.Lateral Corticospinal B. Rubrospinal C. Medullary reticulospinal D.Pontine reticulospinal E. Lateral vestibulospinal F. Medial vestibulospinal
RFA
ANS C. Medullary Reticulospinal ( also facilitates contraction of flexors)
A. lateral corticospinal- mainly flexors
B. Rubrospinal-flexors of the upper limb
D. Pontine reticulospinal- axial and limb extensors
E.Lateral vestibulospinal- Balance-related muscular response
F. Medial vestibulospinal-contraction of neck in coordination with eye movement
The Red nucleus is house the upper motor neurons of which tract?
A. Lateral Corticospinal B. Rubrospinal C. Lateral Reticulospinal D. Medial Reticulospinal E. Anterior Cortiospinal
FA
B. the red nucleus contains the cell bodies of the Rubrospinal tract.
Which of the following tracts is entirly localized within the Anterior compartment of the spinal cord?
A. Corticospinal B .Rubrospinal C. Vestibulospinal D. Reticulospinal E. Spinocerebeller
FA
C. The vestibulospinal tract is localized within the anterior spinal cord compartment. Its main purpose is extension. the other tracts have parts that may travel through the anterior compartment, like the cortciospinal and reticulospinal, however they do not entirely utilize this compartment and contribute both flexion and extension fibers
Motor signals generated by the cortex are coarse and require modulation. Which of the following statements of motor signal modulation is accurate?
A. Basal ganglia and primary somatosensory cortex modulate motor signals generated by the cerebral cortex.
B. Only the cerebellum modulates motor signals generated by the cerebral cortex.
C. Sensory feedback is vital to basal ganglia regulation of motor centers.
D. Dorsal column/medial lemniscal pathways, anterolateral system (ALS), somatosensory cortex, and the spinoreticular tracts provide somatosensory feedback to the motor systems.
AA
CORRECT ANSWER = D. Dorsal column/medial lemniscal pathways, anterolateral system (ALS), somatosensory cortex, and the spinoreticular tracts provide somatosensory feedback to the motor systems.
Basal ganglia and the cerebellum both modulate motor signals generated by the cerebral cortex, making answer choices A and B incorrect.
Sensory feedback is vital to cerebellar regulation of motor centers, making answer choice C incorrect.
Answer choice D is just definitional.
Which of the following start locations of the listed motor tracts is paired correctly?
A. Lateral corticospinal - lateral vestibular nucleus
B. Lateral reticulospinal - pontine reticular formation
C. Medial reticulospinal - pontine reticular formation
D. Rubrospinal - cortex
E. Lateral vestibulospinal - medial vestibular nucleus
AA
ANSWER = C. Medial reticulospinal - pontine reticular formation.
Lateral corticospinal tract starts in the cortex, as per its name CORTicospinal. This rules answer choice A incorrect.
Lateral reticulospinal tract starts at the medullary reticular formation, ruling answer choice B incorrect.
Rubrospinal tract starts at the red nucleus. Think of “rubies are red”.
Lateral vestibulospinal tract begins at the lateral vestibular nucleus, making choice E incorrect.
The medial vestibular tract starts at the medial vestibular nucleus.
Which of the following motor pathways are biased for extension?
A. Medullary Reticulospinal
B. Rubrospinal
C. Lateral vestibulospinal
D. Lateral corticospinal
AA
ANSWER = CHOICE C. Lateral vestibulospinal.
The motor tracts that are located more medially and anterior on the spinal cord are biased for extension. These include Pontine (medial) reticulospinal, Lateral vestibulospinal, and Medial vestibulospinal tracts.
The motor tracts that are located more laterally on the spinal cord are biased for flexion. These include Lateral corticospinal, rubrospinal, and medullary (lateral) reticulospinal (bilateral) tracts.
Which of the following motor systems are degenerated in Amyotrophic Lateral Sclerosis (ALS)?
A. Anterior horn cells, parts of pyramidal tract and primary motor area B. CN V C. CN VI D. CN VII E. CN VIII F. CN IX G. CN X H. CN XI I. CN XII J. Answer choices A, B, D, G, and I K. Answer choices A, B, E, G, and I L. Answer choices A, B, D, H, and I
AA
CORRECT ANSWER = J. Answer choices A, B, D, G, and I
Amyotrophy = atrophy of muscle
Lateral sclerosis = hardening of lateral columns of the spinal cord.
ALS causes the degeneration of anterior horn cells and motor CN (V, VII, X, XII), parts of pyramidal tract, and primary motor areas.
A patient comes in to your clinic complaining of Right arm weakness. He said he realized the weakness while having sex with his husband Fares. During the physical exam you notice that your patients hypothenar eminences are of equal size. You tell the patient “tell me more” and he starts to go into explicit details of their sexual relations. As you go to label “perverted” under your patients name listed as Ryan Averil he states that when Fares puts ice on his nipples he can’t feel any temperature but can feel it everywhere else on his body. What is Ryans diagnosis?
(mm)
When you hear about the right arm weakness you are thinking of lesions affecting the front of the spinal cord which can be ALS, Ant Spinal Synd, and Syringomyelia. The patient starts to tell you that they are having sex so you can rule out Ant Spinal Syndrome because with that there will be sexual dysfunctions. When performing the physical exam equal hypothenar eminences rule out ALS because that presents with loss of muscle bulk in the thenar eminence, arm, and shoulder. Then when telling you about his sex acts he states there is a loss of temperature at a single dermatome on his body which proves your final choice syringomyelia.
A patient is riding a unicycle on a massive interstate because they are on heavy doses of LSD. They are struck by an 18-wheeler and somehow live. After they are stable and not high anymore you question them about their symptoms. They say they can’t feel any temperature in their legs and they have a bilateral extensor plantar response. which of the following is the most likely lesions?
(mm)
A) Brown Sequard
B) Anterior Spinal Artery Syndrome
C) Syringomyelia
D) Wallenburg
Answer is B
C and D are obv to not be the answer because its bilateral in the legs, wallenburg affects medulla so facial probs too and syringomyelia would have to be MASSIVE and prob can’t even affect that low to ruin temp to then entirety of both legs
The diff between A and B would be that ASAS has bilateral Babinski reflex and brown squard would have ipsilateral.
also that ASAS has bilateral retention of vibration and proprio while brown squard loses that ipsilaterally but this wasn’t given in the question stem
