development of the CNS

Question 1

structure of developing brainstem around fourth ventricle

Answer 1

roof plate above, suluc limitans surrounds; 1 alar plate either side below sulcus limitans and fourth ventricle laterally (sensory; equivalent of dorsal); 1 basal plate either side below sulcus limitans and fourth ventricle medially (motor; equivalent of ventral)

Question 2

developing brain: dorsal view of embryo at 4 weeks sections (top to bottom)

Answer 2

all at anterior of neural tube: future forebrain (prosencephalon), future midbrain (mesencephalon), future hindbrain (rhombencephalon - largely cerebellum and brainstem), future spinal cord

Question 3

developing brain: dorsal view of embryo at 5 weeks sections (top to bottom)

Answer 3

future forebrain (divided into telencephalon (cortex) above and diencephalon (thalamus and hypothalamus) below), future midbrain (section of brainstem), future hindbrain (parts of brainstem: pons above then medulla below)

Question 4

developing brain: dorsal view of embryo at 8 weeks sections (top to bottom)

Answer 4

neural tubes begin to form ventricles: forebrain with developing hemispheres laterally, and with lateral ventricle either side of central third ventricle medially (lateral ventricles drain into third ventricle); midbrain containing aquaduct which connects to fourth ventricle in hindbrain (fourth ventricle is medial, developing cerebellum is lateral in hindbrain; cerebellum is far more tightly organised than cortex)

Question 5

3 flexures in developing brain at 4 weeks (from forebrain to hindbrain)

Answer 5

cephalic (midbrain and hindbrain), pontine (pons), cervical (flex and produce spinal cord below)

Question 6

development of forebrain, midbrain and hindbrain at 5 weeks and 8 weeks

Answer 6

telencephalon, diencephalon, midbrain, hindbrain

Question 7

developing brain sections at term

Answer 7

more growth; myelination of brain axons

Question 8

developing cortex: telencephalon structure from ventricle to pia surface (medial to lateral)

Answer 8

migrate from inside out; 6 different layers with different functions: ventricular zone (containing radial glial cell: astrocyte that provides scaffolding) -> subventricular zone -> intermediate zone -> cortical plate -> marginal zone

Question 9

developing cortex: intermediate zone in telencephalon structure from medial to lateral

Answer 9

process of radial glial cell (astrocyte that provides scaffolding) -> trailing process of neurone -> migrating neurone -> leading process of neurone

Question 10

define gyrencepahlic

Answer 10

folding of brain in cortex -> more organisation