UBC NSCI 311 Lecture 2 (Development of the CNS)

Advanced Neuroanatomy - Midterm 1 Content

trilaminar disks form when

during first 3 weeks of development

what layer is ectoderm

outer layer

ectoderm turns into…

neural tube and neural crest cells

what layer is mesoderm

middle layer (red part on either side of notochord)

mesoderm turns into…

muscle, bone, cartilage, fat, etc.

what layer is endoderm

inner layer

endoderm turns into…

gut tube (digestive system)

notochord functionality

signals cells in ectoderm to thicken and differentiate into neural plate (aka induces neurulation)

notochord location/structure

midline part of mesoderm

steps of neurulation

1. notochord signals ectoderm to thicken and differentiate

2. neural folds extend dorsally and medially toward each other, deepening neural groove

3. neural crest cells cluster beside neural groove

4. neural folds close the neural groove, forming the neural tube deep to the ectoderm layer

neural crest cells origin

from tips of ectoderm neural folds

neural crest cells contribute to…

peripheral nervous system sensory structures

neural tube is the basis of…

central nervous system

what does the hollow space of the neural tube turn into

ventricles

rostral and caudal neuropores

the openings at the end of the neural tube, the last to close

incomplete closure of neuropore leads to…

neural tube defects

examples of neural tube defects

1. encephalocele

2. spina bifida

differentiation of prosencephalon (forebrain)

1. telencephalon —> cerebral hemispheres

2. diencephalon —> thalamus, hypothalamus, epithalamus, subthalamus

differentiation of mesencephalon

mesencephalon —> midbrain

differentiation of rhombencephalon (hindbrain)

1. metencephalon —> pons, cerebellum

2. myelencephalon —> medulla oblongata

what is the dividing neural tube divided into

basal and alar plates

in the neural tube, what separates the basal and alar plates

sulcus limitans

characteristics of the alar plate

dorsal, sensory

characteristics of the basal plate

ventral, motor

list of alar and basal plate subsections (dorsal to ventral)

somatic sensory, visceral sensory, visceral motor, somatic motor

where do somites derive from

paraxial mesoderm (closest to neural tube)

what is a somite

epithelial “ball”

what does each somite divide into

sclerotome cells and dermomyotome cells

what does sclerotome become

vertebrae and ribs

what does dermomyotome become (generally)

dermis and skeletal muscle

dermis

parts of skin and sensory receptors

dermomyotome gives rise to…

a dermatome and a myotome (on ipsilateral side)

what is a dermatome

band of skin that is innervated by sensory neurons, each associated with a single spinal nerve

what is a myotome

group of muscle fibers innervated by motor neurons from a single spinal segment

are most skeletal muscles innervated by one or many neurons

many

where do dermis and skeletal muscle precursors arise from

somites

where do motor neurons arise from

neural tube

what muscle cells do motor neurons innervate (location)

from the same spinal level

examples of what neural crest cells become

sensory neurons, neurolemmocytes (Schwann cells), melanocytes 

most superior key dermatome

C5-T1, upper limbs

second most superior dermatome

T4, nipples

second most inferior key dermatome

T10, umbilicus (belly button)

most inferior key dermatome

L2-S2, lower limbs