First Aid USMLE Step 1 – Neurology High-Yield Review PDF

First Aid USMLE Step
1_Neurology
Exam

(Questions and Answers)
2026
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, First Aid USMLE Step 1: Neurology
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1. Describe the ba- - the* notochord* induces overlying ectoderm to differentiate into neuroectoderm
sic embryological and form the neural plate (day 18)
process behind - the neural plate invaginates to form the *neural tube* and at the same time, cells
development of demarginated from the invaginating tube to form the *neural crest cells*
the neural tube




2. What are the The alar and basal plates are basically the dorsal and ventral divisions of the neural
basal and alar tube below the sulcus limitans.
plates?
The alar plate (dorsal) --> sensory neurons of the spinal cord
What do they
give rise to? The basal plate (ventral) --> motor neurons of the spinal cord




3. With regard to
the regions of
the developing
brain:

What are the
three primary
vesicles of the
brain?
2026


, First Aid USMLE Step 1: Neurology
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What are the 5
secondary vesi-
cles they give rise
to?

Name the adult
structures that
arise from the
walls and cavi-
ties of the 5 sec-
ondary vesicles.

4. What does the *What does the notochord give rise to?
notochord give - the notochord gives rise nucleus pulposus of the intervertebral disc in adults
rise to?
*What does the neuroectoderm give rise to?*
What does ---> the neural tube, which then gives rise to
the neuroecto- - CNS neurons
derm give rise - ependymal cells (inner lining of ventricles, makes CSF fluid)
to? - oligodendroglia
- astrocytes
What do the
neural crest cells *What do the neural crest cells give rise to?*
give rise to? - PNS neurons
- Schwann cells
What does the
mesoderm give *What does the mesoderm give rise to?*
rise to? - microglia!

5. In general, what *In general, what are neural tube defects?*
are neural tube - failure of the neuropores to fuse (occurs in the 4th week)
defects? - results in a persistent connections between the amniotic cavity and spinal canal

2026


, First Aid USMLE Step 1: Neurology
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What increases *What increases risk for neural tube defects?*
risk for neural - associated with *low folic acid intake before conception* and then during
tube defects? pregnancy

How are neur- *How are neural tube defects screened for?*
al tube defects - increased *alpha-feto-protein* in amniotic fluid and maternal serum (except in
screened for? spina bifida occulta)
- increased* acetylcholinesterase (AChE) in the amniotic fluid is helpful confirma-
Name the 3 ex- tory test (as fetal AChE in CSF flows through the defect in the amniotic fluid) *
amples of neural
tube defects: *Name the 3 examples of neural tube defects:*
- spina bifida occulta
- meningocele
- meningomyelocele

6. For the follow- *Spinal Bifida Occulta:*
ing neural tube - failure of the neural tube to close at the caudal aspect leading to a failure of the
defects, describe posterior vertebral arch to close
the findings: - the dura is intact
- associated with a *tuft of hair or skin dimple* at the site of the defect
Spinal Bifida Oc-
culta *Meningocele:*
- meninges (but no neural tissue) herniate through the bony defect
Meningocele
*Meningomyelocele:*
Meningomyelo- - meninges and neural tissue (eq: cauda equina) herniate through the bony
cele defect




7.
2026