1. The neural retina is derived from the (A) alar plate (0) choroid (C) neural crest (D) neural tube (E) telencephalic vesicle wall
I-D. The retina is derived from the neural tube, which gives rise to the entire central nervous system (eNS).
2. At birth, the conus medullaris is found at which vertebral level? (A) VT12 (B) VLl (C) VL3 (D) VSl (E) VS4
2-C. At birth, the conus medullaris extends to VL3, and in the adult it extends to the VLI-VL2 inter space. At 8 weeks, the spinal cord extends the entire length of the vertebral canal.
3. Cnudnl herniation of the cerehcllnr tonsils and medulla through the foramen magnum is called (A) Dandy-Walker syndrome (B) Down syndrome (C) Arnold-Chiari syndrome (D) cranium bifidum (E) myeloschisis
3-C. Arnold·Chiari syndrome is a cerebello medullary malformation in which the inferior vermis and medulla herniate through the foramen mag num, resulting in communicating hydrocephalus. Arnold·Chiari syndrome is frequently associated with spina bifida.
4. A newborn has multiple congenital defects due to dysgenesis of the neural crest. Which of the following cells would most likely be spared? (A) Dorsal root ganglion cells (B) Geniculate ganglion cells (C) Melanocytes (D) Motoneurons (E) ParafoUicular cells
4-D. Motoneurons develop from the neural tube, more specifically, from the basal plate. The other options are derivatives of the neural crest.
5. The diencephalon gives rise to all of the fol¬lowing structures EXCEPT the (A) mamillary bodies (B) pineal body (C) subthalamic nucleus (D) adenohypophysis (E) neurohypophysis
5-D. Th~ adenohypophysis (pars distalis, pars tuberalis, and pars intermedia) develops from Rathke po\..ch, an ectodermal diverticulum of the stomodeum. The nellrohypophysisdevelops from the infundibulum of the hypothulumu8.
6. All of the following statements concerning myelination are correct EXCEPT (A) it is accomplished by neural crest cells (B) it is accomplished by Schwann cells in the peripheral nervous system (PNS) (C) it is accomplished by oligodendrocytes in the central nervous system (CNS) (D) it commences in the fourth fetal month (E) it is completed by birth
6-E. Myelination is not complete at birth. The corticospinal tracts are not completely myelinated until the end of the second postnatal year.
7. All of the following statements concerning spina bifida are correct EXCEPT (A) spina bifida results from failure of verte¬bral arches to fuse (B) spina bifida is frequently associated with Arnold-Chiari malformation (C) spina bifida usually occurs in the cervi¬cothoracic region (D) spina bifida occulta is the least severe variation (E) spina bifida with myeloschisis is the most severe variation
7-C. Spina bifida usually occurs in the lumbosacral region.
8. The neural crest gives rise to all of the fol¬lowing cells EXCEPT (A) odontoblasts (B) oligodendrocytes (C) cells of enteric ganglia (D) Schwann cells (E) chromaffin cells
8-B. The neural crest gives rise to dorsal root ganglion cells, the cells of autonomic and enteric ganglia, Schwann cells, satellite cells, and chromaffin cells of the suprarenal medulla. The neuralcrest also gives rise to pigment cells (melanocytes), odontoblasts, meninges, and mesenchyme of the hranchial nrchej;. Oli~() dendrocytes arise from the glioblasts·ofthe neural tuhe.
9-C. The corticospinal tract (pyramid) has its origin in the neocortex of the telencephalon.
10-A.· The tela choroidea gives rise to the choroid plexus.
11-B. The inferior olivary nucleus is derived from the alar plate of the developing medulla.
12-D. The basal plate gives rise to the hypoglossal nucleus.
13-E. The alar plate givef risc to the solitary nucleus.
14-B. The general somatic efferent (GSE) column innervates the lateral rectus muscle.
15-E. The general visceral efferent column (GVE) gives rise to the superior saliva tory nucleus of CN VII. This parasympathetic nucleus innervates the lacrimal, the sublingual, and the submandibular glands and also the palatine and nasal glands.
I6-A. The cerebellum is derived from the alar plate. The alar plate gives rise to the rhombic lip, which becomes the cerebellum.
17-C. The pontine nuclei are derived from the alar plate.
18-D. The special visceral efferent (SVE) column gives rise to motor neurons that migrate into the lateral pontine tegmentum and become the facial nucleus, eN VII.