CNS Development and Brain Divisions

Question 1

What are the three stages in neural tube development?

Answer 1

• neural plate
• neural folds
• neural tube

Question 2

What is the early tissue layer covering the embryo? What type of tissue is it composed of?

Answer 2

• ectoderm

- simple cuboidal epithelium

Question 3

What structure becomes simple columnar epiuthelium from the simple cuboidal?

Answer 3

-neural plate

Question 4

What structure fuses together to form the neural tube?

Answer 4

-neural folds

Question 5

When does the superior neuropore close? When does the inferior neuropore close?

Answer 5

• superior: day 27

- inferior: day 30

Question 6

What are the divisions of the tripartite brain? Pentapartite brain? What differentiates into what?

Answer 6

• prosencephalon -> telencephalon and diencephalon
• mesencephalon -> mesencephalon
• rhombencephalon -> metencephalon and myelencephalon

Question 7

What brain area is the most anterior?

Answer 7

telencephalon

Question 8

How does CSF flow through the brain?

Answer 8

lateral ventricles -> third ventricle -> cerebral aquaduct -> fourth ventricle

Question 9

What is anencephaly?

Answer 9

-failure of cranial end of the neural tube to close

Question 10

What is holoprosencephaly? What facial deformities is it typically associated with?

Answer 10

-failure of prosencephalon to divide into two cerebral hemispheres
-associated with:
+single orbit with two eyes, one eye, or no eye
+proboscis type nose located above eye
+cleft lip and palate

Question 11

Differentiate between spina bifida occulta and cystica.

Answer 11

Occulta:
-results from failure of inferior neuropore to close
-vertebral arches fail to develop in caudal area
-spinal cord functions as normal
Cystica:
-characterized by a sac-like cyst at caudal end of spine
-spinal cord and/or meninges may be found in cyst
-spinal cord function impaired
-lower extremity dysfunction
-bladder and bowel function may be impaired

Question 12

What are the different types of spina bifida?

Answer 12

• meningocele: only meninges in sac
• meningomyelocele: meninges and spinal cord are in sac, abnormal growth of spinal cord, lower extremity paralysis, bowel and bladder dysfunction
• myeloschisis: failure of caudal neural folds to fold, most severe of the defects

Question 13

What is Arnold-Chiari deformity?

Answer 13

-inferior cerebellum and medulla are elongated and protrude into vertebral canal
-medulla and pons are small and deformed
-hydrocephalus
-malformation of lower cranial nerves
+deafness
+tongue, facial muscle, lateral eye movement weakness

Question 14

Structures in lumina, floor, and roof of telencephalon primodia.

Answer 14

lumina: lateral ventricles
floor: basal nuclei, olfactory lobes and nerves
roof: cerebral hemispheres

Question 15

Structures in lumen, roof, walls, and floor of diencephalon primordia.

Answer 15

lumen: third ventricle
roof: epithalamus
walls: thalamus
floor: hypothalamus and infudibulum

Question 16

Structures in lumen, roof, and floor of mesecephalon primordia.

Answer 16

lumen: cerebral aqueduct

roof (tectum): sup and inf colliculi

floor: tegmentum

Question 17

Structures of lumen, roof, and floor of metencephalon primordia.

Answer 17

lumen: 4th ventricle
roof: cerebellum
floor: pons

Question 18

Structures of lumen, main part, and roof of myelencephalon primordia.

Answer 18

lumen: 4th ventricle

main part: medulla oblongata

roof: post choroid plexus

Question 19

What is contained in the myelencephalon/medulla?

• nuclei
• pyramids
• olives
• vital reflex centers
• various nonvital centers

Answer 19

-nuclei
  \+vestibular nuclear complex
  \+sensory nuclei
  \+portions of reticular formation
-pyramids
   \+lateral corticospinal tracts
-olives
  \+nuclei related to cerebellum
-vital reflex centers
  \+cardiac center
  \+vasomotor center
  \+centers related to respiration

Question 20

Structures in the metencephalon

Answer 20

-pons
  \+nuclei
      -cranial nerve V-VIII
      -pontine nuclei (relay between cerebrum and cerebellum)
  \+centers
      -sleep center
      -respiratory centers
-cerebellum

Question 21

Structures of mesencephalon.

Answer 21

-nuclei
   \+cranial nerve III-IV
-tectum
   \+sup (visual reflexes) and inf (auditory and olfactory reflexes) colliculi
-tegmentum
   \+red nucleus
   \+substantia nigra
   \+various tracts

Question 22

What are the functions of the cerebellum?

Answer 22

• coordinates skeletal muscle movements
• maintain equilibrium and posture
• synergic control of muscle activity

Question 23

True or False: like a majority of the structures in the brain, the cerebellum does not have a cortex

Answer 23

false

Question 24

What are peduncles?

Answer 24

large pairs of fiber tracts

Question 25

In the cerebellum, the inferior peduncle connects _________ and ______________.

Answer 25

medulla and spinal cord

Question 26

Middle peduncles connect to ___________

Answer 26

the pons

Question 27

Superior peduncles of the cerebellum connect to the ______________.

Answer 27

midbrain

Question 28

What structures are in the telencephalon?

Answer 28

• olfactory bulb
• basal nuclei (subconscious motor control and muscle tone)
• cerebral cortex (paired lobes, surface with sulci and gyri)

Question 29

What structures are in the diencephalon?

Answer 29

• thalamus (relay center for afferent and efferent info to and from cerebrum and other parts of brain)
• epithalamus (pineal body, habenular nuclei)
• hypothalamus (mammilary bodies involved in olfactory reflexes and emotional responses to odors, supraoptic and paraventricular nuclei)

Question 30

Functions of the diencephalon.

Answer 30

• controls and integrates ANS
• associated with visceral activity
• intermediary between nervous and endocrine systems
• controls normal body temp
• maintains extracellular fluid volume
• biorhythm oscillator

Question 31

What are the habenular nuclei involved in?

Answer 31

-emotional and visceral responses to odors

Question 32

When does the nervous system form during development?

Answer 32

-end of second week to end of eighth week