Chapter 5: Development of the Nervous System

Chapter 5: Development of the Nervous System

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

1. Somites are derived from which one of the following pre-embryonic cell layers?
2. Endoderm
3. Mesoderm
4. Ectoderm
5. Neural crest
6. None of the above

ANS: B

Rationale: Somites are spherical cell clusters that develop from the mesoderm as the neural tube closes.

2. Which one of the following statements about somites is NOT true?
3. The sclerotome develops into the vertebrae and skull.
4. The myotome develops into skeletal muscle.
5. The dermatome develops into skin.
6. Somites are added in a caudal-to-rostral direction.
7. Somites develop adjacent to the neural groove.

ANS: D

Rationale: Somites initially appear in the occipital region, adjacent to the neural groove, and are added in a rostral-to-caudal direction. The anteromedial sclerotome becomes the vertebrae and skull, the posteromedial myotome develops into skeletal muscle, and the lateral dermatome develops into the dermis.

3. Neurons that develop in the ventral region of the neural tube become:
4. Interneurons and projections neurons.
5. Interneurons and the motor neurons that innervate skeletal muscle.
6. Interneurons of the autonomic nervous system.
7. Both A and B
8. All of the above

ANS: B

Rationale: Neurons in the ventral region of the neural tube proliferate to form interneurons and the motor neurons that innervate skeletal muscles. Neurons in the dorsal tube proliferate to form interneurons and projection neurons, whereas neurons from the neural crest form autonomic neurons.

4. Which one of the following forms of spina bifida is the least severe and usually does not result in neural symptoms?
5. Spina bifida with myeloschisis
6. Spina bifida with meningomyelocele
7. Spina bifida with meningocele
8. Spina bifida occulta
9. All forms of spina bifida result in neural symptoms.

ANS: D

Rationale: Spina bifida is a neural tube defect that results when the inferior neuropore does not close, producing a bony defect at the distal end of the tube. The severity of the defect varies, ranging from normal spinal cord function (spina bifida occulta) to severe malformation and exposure of the spinal cord to the surface of the body (myeloschisis).