Lecture 1: CNS Development and Brain Divisions

Question 1

During what embryonic stage does the formation of the nervous system occur?

Answer 1

end of 2nd week - end of 8th week

Question 2

What are the 3 stages in Neural Tube Development?

Answer 2

1. Neural Plate
2. Neural Folds
3. Neural Tube

Question 3

What kind of early tissue layer covers the embryo?

Answer 3

Simple Cuboidal Epithelium = Ectoderm

Question 4

What kind of epithelium does ectoderm turn into that covers the Neural Plate?

Answer 4

Simple cuboidal epithelium along dorsum of embryo becomes simple columnar epithelium = Neural Plate.

Question 5

How is the neural folds formed?

Answer 5

Thickened neural plate folds along the anterior-posterior axis to form the neural groove flanked by the Neural Folds.

Question 6

What forms the neural tube?

Answer 6

Opposing edges of the neural folds fuse along the anterior-posterior axis to form the Neural Tube, which separates from the simple cuboidal ectoderm.

Question 7

At what day does the superior (anterior or cranial) neuropore close by?

Answer 7

Day 27

Question 8

At what day does the inferior (posterior or caudal) neuropore close by?

Answer 8

Day 30

Question 9

What 3 subdivisions of the cranial end of the neural tube make up the Tripartite Brain?

Answer 9

> Prosencephalon (forebrain)

> Mesencephalon (midbrain)

> Rhombencephalon (hindbrain)

Question 10

What 5 subdivisions of the cranial end of the neural tube make up he Pentapartite Brain?

Answer 10

> Telencephalon (most anterior)
Diencephalon

> Mesencephalon

> Metencephalon
Mylencephalon

Question 11

Which two subdivisions make up the rhombencephalon (hindbrain)?

Answer 11

> Metencephalon

> Mylencephalon

Question 12

Which subdivision makes up the mesecephalon (midbrain)?

Answer 12

> Mesencephalon

Question 13

Which two subdivisions make up the prosencephalon (forebrain)?

Answer 13

> Telencephalon (most anterior)

> Diencephalon

Question 14

True or False:

The mesencephalon (midbrain) makes up the cerebral aquaduct.

Answer 14

True

Question 15

True or False:

The rhombencephalon (hindbrain) makes up the third ventricle.

Answer 15

False - rhombencephalon (hindbrain) makes up the fourth (4th) ventricle.

Question 16

Which ventricle does the diencephalon, which is a subdivision of the prosencephalon, make up?

Answer 16

3rd Ventricle

Question 17

Which subdivision of the forebrain makes up the lateral ventricles (1st and 2nd ventricles)?

Answer 17

Telencephalon

Question 18

What is anencephaly?

Answer 18

The failure of the cranial end of the neural tube to close.

Question 19

What is holoprosencephaly a failure of?

Answer 19

Failure of prosencephalon to divide into two cerebral hemispheres.

Question 20

What facial deformities are often associated with holoprosencephaly?

Answer 20

> single orbit with two eyes or one eye or no eye

> proboscis-type nose located above eye

> cleft lip and palate

Question 21

What is spina bifida occulta a result from?

Answer 21

Results from a failure of the inferior neuropore to close.

Question 22

In patients with spina bifida occulta, is the spinal cord function usually normal?

Answer 22

Yes

Question 23

In patients with spina bifida occulta, why does the inferior neuropore fail to close?

Answer 23

Because the vertebral arch(-es) fails to develop in the caudal area.

Question 24

What characterizes spina bifida cystica over spina bifida occulta?

Answer 24

Spina Bifida Cystica is characterized by a sac-like cyst at the caudal end of the spine.

Question 25

What are the 3 forms of spina bifida cystica?

Answer 25

> Meningocele > Meningomyelocele > Myeloschisis

Question 26

What is found in the sac of patients with meningocele form of spina bifida cystica?

Answer 26

ONLY meninges found in sac

Question 27

What is found in the sac of patients with meningomyelocele form of spina bifida cystica?

Answer 27

BOTH meninges and spinal cord are found in sac.

Question 28

Of the three forms of spina bifida cystica, which is the most severe of the defects?

Answer 28

Myeloschisis

Question 29

What causes the spina bifida cystica form, myeloschisis, to occur?

Answer 29

Failure of caudal neural folds to close.

Question 30

True or False: The meningomyelocele form of spina bifida cystica always results in abnormal growth of the spinal cord.

Answer 30

True

Question 31

Other than a protruding sac on the caudal end of a patient with spina bifida cystica, what loss of function would patients with meningomyelocele present with?

Answer 31

> lower extremity paralysis > bowel and bladder dysfunction > loss of sensation to lower limbs

Question 32

What is the Arnold-Chiari deformity?

Answer 32

> inferior cerebellum and medulla are elongated and protrude into vertebral canal > medulla and pons are small and deformed > hydrocephalus > malformation of lower cranial nerves (CN 6-12) - deafness - tongue, facial muscle, lateral eye movement weakness

Question 33

What does the floor of the telencephalon primordia consist of?

Answer 33

> basal nuclei (ganglia) | > olfactory lobes and nerves

Question 34

What does the roof of the telencephalon primordia consist of?

Answer 34

> cerebral hemispheres

Question 35

What does the lumina of the telencephalon primordia consist of?

Answer 35

> lateral ventricles (I, II)

Question 36

What does the floor of the diencephalon primordia consist of?

Answer 36

> hypothalamus | > infundibulum

Question 37

What does the walls of the diencephalon primordia consist of?

Answer 37

> thalamus

Question 38

What does the roof of the diencephalon primordia consist of?

Answer 38

> epithalamus

Question 39

What does the lumen of the diencephalon primordia consist of?

Answer 39

third ventricle

Question 40

What does the floor of the mesencephalon primordia consist of?

Answer 40

> tegmentum

Question 41

What does the roof (tectum) of the mesencephalon primordia consist of?

Answer 41

> superior colliculi | > inferior colliculi

Question 42

What does the lumen of the mesencephalon primordia consist of?

Answer 42

> cerebral aqueduct (of Sylvius)

Question 43

What does the floor of the metencephalon primordia consist of?

Answer 43

> pons

Question 44

What does the roof of the metencephalon primordia consist of?

Answer 44

> cerebellum

Question 45

What does the lumen of the metencephalon primordia consist of?

Answer 45

> part of fourth ventricle

Question 46

What does the lumen of the myelencephalon primordia consist of?

Answer 46

> rest of fourth ventricle

Question 47

What does the main part of the myelencephalon primordia consist of?

Answer 47

> medulla oblongata

Question 48

What does the roof of the myelencephalon primordia consist of?

Answer 48

> posterior choroid plexus

Question 49

What are the nuclei of the medulla, which is part of the myelencephalon?

Answer 49

> vestibular nuclear complex > sensory nuclei > portions of reticular formation

Question 50

What vital reflex centers are found in the medulla, which is part of the myelencephalon?

Answer 50

> cardiac center > vasomotor center > centers related to respiration

Question 51

What are pyramids and olives of the medulla oblongata?

Answer 51

Pyramids: > consist of lateral corticospinal tracts (massive fiber tracts that carry information from the cerebral cortex to the spinal cord) Olives: > site of nuclei related to cerebellum

Question 52

Which nuclei are found in the pons of the metencephalon?

Answer 52

> cranial nerve nuclei 5 - 8 | > pontine nuclei -> which relay between the cerebrum and cerebellum

Question 53

Where are the sleep center and respiratory center found within the metencephalon?

Answer 53

Pons

Question 54

Is the cerebellum from the metencephalon?

Answer 54

Yes

Question 55

What is the function of the cerebellum?

Answer 55

> coordinate skeletal muscle movements > maintain equilibrium and posture > synergic control of muscle activity

Question 56

True or False: The cerebellum is connected to other parts of the brain via large pairs of fibers tracts called peduncles.

Answer 56

True

Question 57

What does the inferior peduncle connect the cerebellum to?

Answer 57

> medulla and spinal cord

Question 58

What does the middle peduncle connect the cerebellum to?

Answer 58

> pons

Question 59

What does the superior peduncle connect the cerebellum to?

Answer 59

> midbrain

Question 60

Which cranial nerve nuclei are found in the mesencephalon?

Answer 60

> CN nuclei 3-4

Question 61

What makes up the roof (tectum) of the mesencephalon?

Answer 61

> superior colliciuli (visual reflexes) | > inferior colliculi (auditory and olfactory reflexes)

Question 62

What is found in the tegmentum of the mesencephalon?

Answer 62

> red nucleus > substantia nigra > various tracts

Question 63

What does the thalamus function to do?

Answer 63

> major relay center for afferent and efferent information to and from cerebrum and other areas of the brain

Question 64

What does the epithalamus function to do?

Answer 64

> habenular nuclei involved in emotional and visceral responses to odors (cologne and perfume is designed to cause a visceral response from the epithalamus) > pineal body (we don't know what it does)

Question 65

What is the hypothalamus?

Answer 65

> mamillary bodies involved in olfactory reflexes and emotional responses to odors > supraoptic and paraventricular nuclei

Question 66

What are the functions of the hypothalamus?

Answer 66

> controls and integrates ANS > associated with many kinds of visceral activity > intermediary between nervous and endocrine systems > controls normal body temperature > maintains extracellular fluid volume > Biorhythm oscillator

Question 67

What does the basal nuclei (ganglia) of the telencephalon do?

Answer 67

> subconscious motor control and muscle tone

Question 68

What is the cerebral cortex of the telencephalon divided into?

Answer 68

> divided into paired lobes | > surface with gyri (hills) and sulci (valleys)