Development of the Brain Dennis T#2

Question 1

What are the derivatives of forebrain (Prosencephalon)?

Answer 1

Telencephalon & Diencephalon

Question 2

Derivatives of midbrain?

Answer 2

Mesencephalon

Question 3

What are the hind brain (Rhombenccephalon) derivatives?

Answer 3

Metencephalon & Myelencephalon

Question 4

Derivatives of the telencephalon and diencephalon?

Answer 4

Telencephalon: Lateral ventricles and cerebral hemispheres

Diencephalon: Thalamus hypothalamus epithalamus… third ventricle

Question 5

Mesencehpalon derivatives?

Answer 5

Midbrain & aqueduct

Question 6

Metencephalon and Myelecephalon derivatives?

Answer 6

Metencephalon: Pons and cerebellum and upper part of 4th ventricle

Myelencephalon: Medulla and lower part of 4th ventricle

Question 7

What are the three flexures?

Answer 7

Midbrain (Mesencephalic) Flexure
Cervical flexure
Pontine flexure

Question 8

What flexures are in the hindbrain?

Answer 8

Cervical flexure which separates hindbrain form spinal cord- defined at C1 superior rootlet @ foramen magnum

Pontine flexure which demarcates metencephalon from myelencephalon

Question 9

Hindbrain derivatives?

Answer 9

Myelencephalon: medulla oblongata

Metencephalon: pons and cerebellum

Cavity of hindbrain is the 4th ventricle

Question 10

What do the neuroblasts in alar plates form?

Answer 10

nucleus gracilis and nucleus cuneatus. Both associate with pathway for sensory info the PCML (DCML)

Question 11

what are pyramids and where are the found?

Answer 11

Caudal myelencephalon

ventral structure consisting of CST fibers, important for regulating motor movement from cerebral cortex

Question 12

In the rostral myelencephalon what happens when pontine flexure begins to move?

Answer 12

Pontien flexure causes walls of medulla to move laterally and the roof plate is thinned and cavity is part of 4th ventricle

Question 13

Describe the relation of alar plates to the basal plates once pontine flexure is established?

Answer 13

Alar plate becomes lateral to the basal plates with expansion and flattening of the tissue

Question 14

Neuroblasts from the basal plate develop into motor neurons and those nuclei organize themselves into columns. What are the columns?

Answer 14

GSE
SVE
GVE

Question 15

Neuroblasts in the alar plates of he medulla form neurons that are arranged in columns similar to basal plates. What are they?

Answer 15

GVA
SVA
GSA
SSA

Question 16

What forms neurons in olivary nuclei?

Answer 16

Neuroblasts from alar plates that migrate more ventrally

Question 17

What do the walls of the metencephalon form?

Answer 17

Pons and cerebellum and the cavity forms 4th ventricle

Question 18

In the metencephalon, what does the pontine flexure do?

Answer 18

forces walls of pons out laterally spreading the gray matter in the floor of 4th ventricle and neuroblasts of basal plate develop into motor nuclei

Question 19

Cerebellum develops from ____.

Answer 19

Dorsal parts of alar plates

Question 20

How does the cerebellum develop?

Answer 20

Cerebellar swellings project into 4th vent and fuse in median plane and overgrow rostral 4th vent pons and medulla. Alar plates will form central nuclei pontine cochlear nuclei

Question 21

How does the choroid plexus form

Answer 21

Emendymal roof of the 4th ventricle is covered with Pia mater, which is derived from the hindbrain mesesnchyme. The pia mater and the ependymal roof is called the Tela Choroidea.

The tela choroidea proliferates and invests into 4th vent forming choroid plexus and then secretes ventricle fluid

Question 22

When the outpockets from the 4th ventricle rupture what is formed?

Answer 22

Median and lateral apertures

Question 23

What are the superior and inferior colliculi and where are they from?

Answer 23

Come from midbrain

Neuroblasts of the alar plates that migrate into the tectum

Question 24

What do the neuroblasts of the basal plate form?

Answer 24

Midbrain
Tegmental nuclei (Red nuclei involved in movement, reticular formation brain alertness, CN 3 and 4)

Question 25

What forms the cerebral aqueduct?

Answer 25

midbrain | neural canal narrowing and it will connect 3rd and 4th ventricles

Question 26

The swellings in the lateral walls of the 3rd ventricle in the diencephalon form ____.

Answer 26

Thalamus, hypothalamus and epithalamus

Question 27

Describe development of thalamus.

Answer 27

Diencephalon | Develops and bulges into a cavity and fuses at the midline in ~70% of brains forming interthalamic adhesion

Question 28

Describe hypothalamus development.

Answer 28

Diencephalon Comes from neuroblasts in the intermediate zone. Endocrine and homeostatic nuclei develop and mammillary bodies form on the ventral surface

Question 29

Epithalamus comes from __?

Answer 29

From roof and dorsal portion of lateral wall

Question 30

What is the pineal gland?

Answer 30

median outgrowth of the roof of diencephalon

Question 31

Pituitary gland development?

Answer 31

(BOARDS) The anterior pituitary is endocrine tissue and the posterior is neural tissue. Two embryonic sources: 1. Hypophyseal diverticulum which is an upgrowth of roof of stomodeum (oral ectoderm) 2. Neurohypophyseal diverticulum (Rathke's pouch) downgrowth of diencephalon (neuroectoderm)

Question 32

Describe the 4 steps to hypophyseal diverticulum development.

Answer 32

1. projects from roof of stomodeum by 3rd week 2. constricts its attachment from oral cavity 3. Passes through cranium and contact infundibulum at week 5 4. Regresses from oral cavity at 6th week

Question 33

What does the telencephalon consist of?

Answer 33

Median part and two cerebral vesicles, primordia of the cerebral hemispheres. The cavity corms anterior 3rd ventricle but largely lateral ventricle.

Question 34

What separates and defines caudate and lentiform (putamen and globus pallidus) nuclei?

Answer 34

Fibers of the IC pass through the corpus striatum

Question 35

Holoprosencephaly (HPE), what is it?

Answer 35

incomplete separation of cerebral hemispheres. Most cases are associated with facial abnormalities such as cyclopia premaxillary agenesis, proboscis, single nostril, hypotelorism or facial clefts. Severe and relatively common defect!

Question 36

Describe the genetics of HPE.

Answer 36

Over 12 loci! SHH is the key player but there are others as well. It results in impaired forebrain dev and impacts FNP development. Usually results in early fetal death

Question 37

What is the lamina terminalis?

Answer 37

largest and most rostral end of the bundles of cerebral commissures. It extends from roof of diencephalon to optic chiasm. Within the lamina other commissures form!

Question 38

What is the anterior commissure?

Answer 38

Interconnects temporal lobes within each hemisphere

Question 39

Hippocampal commisure?

Answer 39

Interconnects the hippocampi within each hemisphere

Question 40

Corpus Callosum?

Answer 40

Largest commissure links hemispheres along the length. It grows and extends beyond lamina terminalis anterior portion forms first and the posterior portion forms in fetal life

Question 41

What is the septum pellicudium?

Answer 41

Thin plate of brain tissue containing nerve cells and fibers. Divides

Question 42

How are layers produced in the cerebral cortex?

Answer 42

Cortical layers are laid down from deep to superficial. Youngest neurons are on the outer surface and oldest are the deepest. Layer 6 is first produced Layer 1 is last produced

Question 43

What is Lissencephaly?

Answer 43

Incomplete neural migration during months 3 and 4 of gestation. Initally the infant appears normal, but later develop siezures and profound mental deficiency and mild spastic quadriplegia. It is called smooth brain, they lack gyri and sulci.

Question 44

What is agyria?

Answer 44

Seen in Lissencephaly | lack of gyri

Question 45

What is pachygyri?

Answer 45

Lissencephaly | Thick and broad unorganized gyri

Question 46

What is neuronal heterotopia?

Answer 46

Cells in aberrant positions compared to normal brain enlarged ventricles and malformation of the corpus callosum are also compon

Question 47

Microcephaly?

Answer 47

Lack of coordinated brain and skull growth where calvaria and brain are small and face is normal sized. Zika virus, cytomegalovirus, rubella, toxoplasma gondii can cause it. Maternal alcohol abuse ionizing radiation, or autosomal recessive primary microcephaly are causes.