Chapter 4 : Development of the Nervous Systems (2) Flashcards
1. The anterior and posterior neuropores close during which week of embryonic development? (A) Second (B) Third (C) Fourth (D) Fifth (E) Sixth
1-C. The anterior and posterior neuropores close during the fourth week of embryonic development: the anterior on day 25, the posterior on day 27. Failure of the anterior neuropore to close results in anencephaly; failure of the posterior neuropore to close results in myeloschisis.
2. At birth, the conus medullaris is found at which vertebral level? (A) VT12 (B) VL1 (C) VL3 (D) VS1 (E) VS4
2-C. At birth, the conus medullaris extends to VL3, and in the adult it extends to the VL1-VL2 interspace. At 8 weeks, the spinal cord extends the entire length of the vertebral canal.
3. Failure of the anterior neuropore to close results in (A) hydrocephalus (B) anencephaly (C) mongolism (D) craniosynostosis (E) meningoencephalocele
3-B. Failure of the anterior neuropore to close results in anencephaly. The brain fails to develop; no cranial vault is formed.
4. Caudal herniation of the cerebellar tonsils and medulla through the foramen magnum is called (A) Dandy-Walker syndrome (B) Down's syndrome (C) Arnold-Chiari syndrome (D) cranium bifidum (E) myeloschisis
4-C. Arnold-Chiari syndrome is a cerebellomedullary malformation in which the inferior vermis and medulla herniate through the foramen magnum, resulting in communicating hydrocephalus. Arnold-Chiari syndrome is frequently associated with spina bifida.
4. Caudal herniation of the cerebellar tonsils and medulla through the foramen magnum is called (A) Dandy-Walker syndrome (B) Down's syndrome (C) Arnold-Chiari syndrome (D) cranium bifidum (E) myeloschisis
4-C. Arnold-Chiari syndrome is a cerebellomedullary malformation in which the inferior vermis and medulla herniate through the foramen magnum, resulting in communicating hydrocephalus. Arnold-Chiari syndrome is frequently associated with spina bifida.
5. The flexure that develops between the metencephalon and the myelencephalon is called the (A) cephalic flexure (B) mesencephalic flexure (C) pontine flexure (D) cerebellar flexure (E) cervical flexure
5-C. The pontine flexure develops between the metencephalon (pons) and the myelencephalon
(medulla). The pontine flexure results in lateral expansion of the walls of the metencephalon and myelencephalon, stretching of the roof of the fourth ventricle, and widening of the floor of the fourth ventricle (rhomboid fossa).
- Which of the following statements best describes the sulcus limitans?
(A) It is found in the interpeduncular fossa
(B) It is located between the alar and basal plates
(C) It separates the medulla from the pons
(D) It separates the hypothalamus from the thalamus
(E) It separates the neocortex from the allocortex
6-B. The sulcus limitans separates the sensory alar and motor basal plates. It is found in the
developing spinal cord and on the surface of the adult rhomboid fossa of the fourth ventricle.
The bulbopontine sulcus separates the medulla from the pons. The hypothalamic sulcus separates
the thalamus from the hypothalamus. The rhinal sulcus separates the neocortex from the
allocortex.
8. The diencephalon gives rise to all of the following structures EXCEPT the (A) mamillary bodies (B) pineal body (C) subthalamic nucleus (D) adenohypophysis (E) neurohypophysis
8-D. The adenohypophysis (pars distalis, pars tuberalis, and pars intermedia) develops from
Rathke’s pouch, an ectodermal diverticulum of the stomodeum. The neurohypophysis develops from the infundibulum of the hypothalamus.
8. The diencephalon gives rise to all of the following structures EXCEPT the (A) mamillary bodies (B) pineal body (C) subthalamic nucleus (D) adenohypophysis (E) neurohypophysis
8-D. The adenohypophysis (pars distalis, pars tuberalis, and pars intermedia) develops from
Rathke’s pouch, an ectodermal diverticulum of the stomodeum. The neurohypophysis develops
from the infundibulum of the hypothalamus.
9. The alar plate gives rise to all of the following structures EXCEPT the (A) dentate nucleus (B) inferior olivary nucleus (C) nucleus gracilis (D) nucleus ambiguus (E) cerebellar cortex
9-D. The alar plate of the mantle layer gives rise to sensory relay nuclei and the cerebellum.The nucleus ambiguus, a SVE nucleus, is derived from the basal motor plate.
- All of the following statements concerningmyelination are correct EXCEPT it
(A) is accomplished by neural crest cells
(B) is accomplished by Schwann cells in theperipheral nervous system (PNS)
(C) is accomplished by oligodendrocytes inthe central nervous system (CNS)
(D) commences in the fourth fetal month
(E) is completed by birth
10-E. Myelination is not complete at birth. The corticospinal tracts are not completely myelinated
until the end of the second postnatal year.
- All of the following statements concerningspina bifida are correct EXCEPT
(A) spina bifida results from failure of vertebralarches to fuse
(B) spina bifida is frequently associated withArnold-Chiari malformation
(C) spina bifida usually occurs in the cervicothoracicregion
(D) spina bifida occulta is the least severevariation
(E) spina bifida with myeloschisis is the mostsevere variation
11-C. Spina bifida usually occurs in the lumbosacral region.
- All of the following statements concerningthe neural tube are correct EXCEPT it
(A) lies between the surface ectoderm andthe notochord
(B) is completely closed by the sixth week
(C) contains the neural crest
(D) gives rise to the central nervous system
(CNS)
(E) gives rise to myelin-producing cells
12-C. The neural tube, which lies between the surface ectoderm and the notochord, gives rise
to the brain and spinal cord. Closure is already complete in the fifth week. The neural crest lies
between the neural tube and the surface ectoderm. The neural tube gives rise to oligodendrocytes,
which produce the myelin of the central nervous system (CNS).
13. The cerebellum develops from all of thefollowing structures EXCEPT the (A) rhombencephalon (B) metencephalon (C) rhombic lips (D) alar plates (E) myelencephalon
13-E. The cerebellum arises from the alar plates of the rhombencephalon, which form the rhombic lips. The metencephalon, a division of the rhomben cephalon, includes the pons and the cerebellum. The myelencephalon develops from the rhomben cephalon and becomes the medulla oblongata.
14. The neural crest gives rise to all of thefollowing cells EXCEPT (A) odontoblasts (B) ohgodendrocytes (C) cells of enteric ganglia (D) Schwann cells (E) chromaffin cells
14-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 neural crest also gives rise to pigment cells (melanocytes), odontoblasts, meninges, and
mesenchyme of the branchial arches. Oligodendrocytes arise from the glioblasts of the neural
tube.
