E2 Lundy-Ekman Review Questions Ch 17

Front 1

1. When do the organs form during development?

Back 1

During the embryo stage, from the second to the end of the eighth week, the organs are formed.

Front 2

2. List the steps in formation of the neural tube.

Back 2

Neural tube formation:
a. A thickening of the ectoderm becomes the neural plate.
b. The edges of the plate move toward each other, forming the neural grove.
c. The folds touch in the dorsal midline, first in the future cervical region.
d. The folds fuse together, forming a tube that detaches from the neural crest cells and form the ectoderm that will become skin.

Front 3

3. What is a myotome?

Back 3

In early development, a myotome is the part of the somite that will become muscle. After the embryo stage, a myoteme is a group of muscle innervated by a segmental spinal nerve.

Front 4

4. Describe the changes in the neural tube that leads to formation of the brain.

Back 4

After the superior neuropore closes, the region of the neural tube that will become the brain expands to form three enlargements: the hindbrain, midbrain, and forebrain. Next, the hindbrain divides into the myelecephalon and metencephalon, while the forebrain divides into the diencephalon and telencephalon. The myelencephalon and metencephalon further differentiate to become the medulla, pons, and cerebellum. The telencephalon becomes the cerebral hemispheres.

Front 5

5. List the progressive process of cellular-level development.

Back 5

The progressive developmental processes are cellular proliferation, mitigation, and growth; extension of axons to target cells; formation of synapses; and myelination of axon.

Front 6

6. Describe the regressive process of cellular-level development.

Back 6

The regressive developmental processes are neuronal death and axon retraction.

Front 7

7. Explain the concept of "growing into deficit."

Back 7

"Growing into deficit" is the appearance of sign of nervous system damage during infancy and childhood due to nervous system damage that occurred earlier. The signs are not evident until the infant or child reaches the age when the damaged system(s) would normally have become functional.

Front 8

8. Describe the anatomical deficit in each of the following: anencephaly, Arnold-Chiari malformation, and the four types of spina bifida.

Back 8

Anencephaly is the development of only a rudimentary brainstem, w/o cerebral and cererbellar hemispheres. the Arnold-Chiari deformity is a developmental malformation of the hindbrain, with an elongated inferior cerebellum and medulla that protrude through the vertebral canal. The next four are all due to incomplete closure of the caudal neural tube: in spina bifita occulta, neural tissue does not protrude through the bony defect; in meningocele, the meninges protrude through the bony defect; in meningomyelocele, neural tissue and meninges protrude outside the body; and in myeloschisis, a malformed spinal cord is open to the surface of the body.

Front 9

9. What are the differences b/t Arnold-Chiari type I and type II?

Back 9

The Arnold-Chiari malformation is a developmental deformity of the hindbrain. In Type I, the cerebellar tonsils protrude through the foramen magnum into the vertebral canal, and the medulla and pons are small and malformed. Frequently there are no symptoms, or symptoms are delayed until adolescence or adulthood. Headaches, sensory and motor disorders, facial and tongue weakness, hearing loss, dizziness, weakness of lateral eye movements, impaired coordination, and visual disturbances are the most common signs and symptoms. In Type II, the signs are visible during infancy. The brainstem and cerebellum protrude into the vertebral canal. Signs include paralysis of the sternocleidomastoid muscles, deafness, bilateral paresis of lateral eye movements, and facial weakness. Type II is usually associated w/ meningomyelocele.,

Front 10

10. About half of the cases of severe mental retardation are associated w/ what developmental defect?

Back 10

Severe mental retardation is associated w/ defects in the structure of dendrites and dendritic spines.

Front 11

11. What is cerebral palsy? List the major types of cerebral palsy. What causes cerebral palsy?

Back 11

CP is a disorder of movement and postural control due to permanent, nonprogressive damage of a developing brain. The major type of CP are spastic, athetoid, and mixed. Causes of CP include abnormalities, disorders of the immune system, coagulation disorders, infections, trauma, and hypoxia.

Front 12

12. What are critical periods?

Back 12

Critical periods are the time when neuronal projections compete for synaptic sites. Normal function of neural systems is dependent on appropriate experience during the critical period.