CompTIA
Checkpoint
ISC
HP
Dell
EC-Council
EXIN
Fortinet
ITIL®
Juniper
PMI
Microsoft
VMware
Avaya
Google
Salesforce
Amazon
Palo Alto Networks
Certiport
ISC2
All Vendors
  2. Home
  3. Exams
  4. USMLE
  5. STEP1

Free STEP1 Exam Braindumps (page: 23)

Page 23 of 213
PDF with 845 Questions

Which of the following thalamic nuclei subserves a motor function?

  1. dorsomedial nucleus
  2. lateral geniculate nucleus
  3. medical geniculate nucleus
  4. ventral lateral nucleus
  5. ventral posterior medial nucleus

Answer(s): D

Explanation:

The ventral lateral nucleus of the thalamus receives projections from the deep cerebellar nuclei and, in turn, sends projections to the motor cortex. It is thus functionally defined as a thalamic motor nucleus. The dorsomedial nucleus (choice A) is considered a limbic nucleus of the thalamus as it receives projections from the amygdala and olfactory cortex, and projects to the prefrontal cortex and hypothalamus. The lateral (choice B) and medial geniculate (choice C) nuclei and the ventral posterior medial nucleus (choice D) are considered sensory nuclei as they receive information mediating vision, audition, and somatosensory signals from the face, respectively. In turn, these three brain areas project to the somatosensory cortex.



A neurology resident is testing the jaw-jerk reflex in a patient by tapping gently on the right masseter muscle and observing elevation of the mandible. What is the location of the neuronal cell bodies of the proprioceptive fibers mediating the jaw-jerk reflex?

  1. mesencephalic trigeminal nucleus
  2. motor trigeminal nucleus
  3. principal (main) trigeminal nucleus
  4. spinal trigeminal nucleus
  5. trigeminal (gasserian) ganglion

Answer(s): A

Explanation:

The jaw-jerk reflex is a monosynaptic (stretch) reflex for the masseter muscle. Proprioceptive fibers from the muscle travel by way of the trigeminal nerve back to their cell bodies in he mesencephalic trigeminal nucleus. Projections from this nucleus synapse on motor neurons of the motor trigeminal nucleus (choice B) which elicits contraction of the masseter muscle. The principal (main) trigeminal nucleus (choice C) receives light touch sensory information from the face, whereas the spinal trigeminal nucleus (choice D) receives pain and temperature sensations. The trigeminal (gasserian) ganglion (choice E) contains the cell bodies of all sensory neurons projecting to the principal (main) and spinal trigeminal nuclei.



Which of the following statements concerning muscle spindles is correct?

  1. Activation of type Ia sensory fibers from a given spindle leads to inhibition of the muscle in which that spindle is located.
  2. Alpha motoneurons synapse directly with intrafusal muscle fibers.
  3. Each intrafusal fiber is innervated by two different gamma motoneurons.
  4. Only one type of intrafusal muscle fiber (cell) is present in most muscle spindles.
  5. Type Ia sensory fibers from a spindle form direct synaptic contact with alpha motoneurons in the spinal cord.

Answer(s): E

Explanation:

The type Ia sensory fibers from a spindle form direct excitatory synapses with alpha motoneurons.
Activation of type Ia sensory fibers (choice A) leads to excitation of the muscle in which that spindle is located. Alpha motoneurons (choice B) synapse with extrafusal muscle fibers, whereas gamma motoneurons synapse with intrafusal muscle fibers. Each intrafusal muscle fiber (choice C) is innervated by only one gamma motoneuron. Each muscle spindle contains a mixture of both nuclear bag and nuclear chain intrafusal fibers, not just one type as indicated in choice D.



Which of the following is characteristic of damage to the corticospinal (pyramidal) system?

  1. Babinski's sign
  2. flaccid paralysis and hypotonia
  3. immediate muscle degeneration and atrophy
  4. intention tremor
  5. loss of deep tendon reflexes

Answer(s): A

Explanation:

The Babinski sign--dorsiflexion of the great toe in response to stroking the plantar aspect of the foot-- is a characteristic sign of pyramidal tract involvement. Signs and symptoms of corticospinal tract injury that are nearly always apparent to some degree include spastic paralysis, hypertonia, loss of deep tendon reflexes, and hyperactive abdominal and cremasteric reflexes. Flaccid paralysis and hypotonia (choice B) are commonly seen following lower motoneuron injury, as is loss of deep tendon reflexes (choice E). Muscle degeneration and atrophy (choice C) are not characteristic symptoms of corticospinal tract damage. The presence of an intention tremor (choice D) is a sign of cerebellar damage, and is not seen with corticospinal tract lesions.



Page 23 of 213



Post your Comments and Discuss USMLE STEP1 exam with other Community members:

Raj commented on October 20, 2024
Great article! I especially appreciated the way you broke down the questions
UNITED STATES
upvote

Jim commented on October 20, 2024
Some of the questions are tought. Need to practice more..
UNITED STATES
upvote

Jim commented on October 20, 2024
Good site for Salesforce certification
UNITED STATES
upvote

Tom commented on October 20, 2024
This is a very good resource
UNITED STATES
upvote

Marcellus Werifah commented on October 20, 2024
Verified answers
UNITED STATES
upvote

samir commented on October 20, 2024
good practice
AUSTRIA
upvote

Patric commented on October 20, 2024
The main thing about this exam dump is that the PDF is not free. And that is what I needed. So I had to pay for that but they offer 50% discount if you buy 2 or more exams.
Spain
upvote

Nathan commented on October 20, 2024
Using dumps are my last resort. And that is what I ended up using with this exam to pass. The exam is extremely difficult.
France
upvote

Marcellus Werifah commented on October 20, 2024
Who decides what is the correct in case of conflicts
UNITED STATES
upvote

Marcellus Werifah commented on October 20, 2024
Novice. Would need detailed explanation of any questions
UNITED STATES
upvote

Maya commented on October 20, 2024
It would be great if all answers are supported by reference link.
UNITED KINGDOM
upvote

Maya commented on October 20, 2024
good material
UNITED KINGDOM
upvote

Jay commented on October 20, 2024
Interesting selection of questions
GREECE
upvote

Vinod Kumar Ramaswamy commented on October 20, 2024
ITS VERY USEFUL
UNITED KINGDOM
upvote

Srikanth commented on October 20, 2024
Useful to prepare for the exam
Anonymous
upvote

Alex commented on October 20, 2024
This exam is super duper hard. So prepare for it guys. I only passed it because of these questions. God bless the owner of this site.
UNITED STATES
upvote

Petrious commented on October 20, 2024
The site provides good content and very reliable support team. Very quick to reply to questions.
GERMANY
upvote

Rashmi commented on October 20, 2024
Good Content
Anonymous
upvote

Manish commented on October 19, 2024
Hi it's a good initiative
Anonymous
upvote

Veronica commented on October 19, 2024
Brain dump questions are new to me...I'm not sure how to respond to this since I only answered a handful of questions
UNITED STATES
upvote

Kamran commented on October 19, 2024
Useful resource
UNITED STATES
upvote

AC commented on October 19, 2024
For a moment no, comment, still moving well
Anonymous
upvote

johnny commented on October 19, 2024
great insight
Anonymous
upvote

Marc commented on October 18, 2024
What the best way to learn terraform?
UNITED STATES
upvote

murad commented on October 18, 2024
Very helpful for certs
JORDAN
upvote

Jack commented on October 18, 2024
are these legit ?
Anonymous
upvote

Juan commented on October 18, 2024
From until what page number is enough to pass the certification?
Anonymous
upvote

Sandeep commented on October 18, 2024
This is very helpful for exam crack
UNITED STATES
upvote

Cheron commented on October 18, 2024
Before all i thank to you for your support. I passed my 2 exams I purchased with full version. I got 90% in one exam and in 2 exam I got 86%.
Anonymous
upvote

LA commented on October 18, 2024
Hi there, I have scheduled my EXAM and will share my experience if these questions are valid or not.
Anonymous
upvote

Mazin commented on October 18, 2024
Good questions
Anonymous
upvote

Test commented on October 18, 2024
Test are these teak answeres?
Anonymous
upvote

anonymous commented on October 17, 2024
can someone tell me if this is real questions
UNITED STATES
upvote

Steven commented on October 17, 2024
Questions are spot on and I passed the exam.
UNITED STATES
upvote