USMLE STEP 1 Neurology exam 2023 with 100% correct answers

The notochord induces what to differentiate into what? - correct answer Induces overlying ECTODERM to differentiate into NEUROECTODERM and form NUERAL PLATE Neural plate then gives rise to? - correct answer Neural tube and neural crest cells Notochord becomes what? - correct answer Nucleus pulposus of the intervertebral disks in adults Alar Plate - correct answer Dorsal [Sensory] Same orientation as spinal cord Basal Plate - correct answer Ventral [Motor] Same orientation as the spinal cord How does FGF affect chordin and noggin? - correct answer FGF regulates chordin and noggin to down regulate BMP which leads to neural plate induction Three Primary Vesicles - correct answer 1. Forebrain [Prosencephalon] 2. Midbrain [Mesencephalon] 3. Hindbrain [Rhombencphaln] The Forebrain gives rise to: - correct answer 1. Telencephalon [Cerebral hemispheres, lateral ventricles] 2. Diencephalon [Thalamus, Third Ventricle] The Midbrain gives rise to: - correct answer 1. Mesencephalon [Midbrain, aqueduct] The Hindbrain gives rise to: - correct answer 1. Metencephalon [Pons, cerebellum, upper part of the fourth ventricle] 2. Myelencephalon [Medulla, Lower part of the fourth ventricle] CNS/PNS Origins - correct answer Neuroectoderm = CNS neurons, ependymal cell [Inner lining of ventricles, makes CSF], oligodendrocytes, astrocytes Neural crest cells = PNS, schwann cells Mesoderm = Microglia [Like Macrophages, originate from Mesoderm] Neural tube defects - correct answer NEUROPORES fail to fuse [4th week] → Persistent connection between amniotic cavity and spinal canal Associated with: 1. Low folate levels befo