Chapter 8 Flashcards
Pre embryonic stage (conception to day 14)
Fertilization of ovum in the uterine tube
Fertilized ovum begins cell division
Solid sphere of cells forms → cavity opens up in the sphere
outer layer of sphere becomes fetal contribution to placenta
Inner cell mass becomes embryo
Implantation → inner cell mass develops into embryonic disk
Ectoderm, endoderm, mesoderm forms
Embryonic stage ( day 15 → end of 8th week)
Organs begin to form
Formation of nervous system begins
Ectoderm develops into…
Sensory organs, epidermis, and nervous system
Mesoderm develops into…
Dermis, muscles, skeleton, excretory and circulatory systems
Endoderm develops into…
Gut, liver, pancreas, respiratory system
Fetal stage (end of 8th week → to birth)
Nervous system develops fully
Myelination begins
Nervous system phases
1) tissue that will become NS comes together to form a tube running along the back of the embryo
2) when the tube closes, brain formation begins
Neural plate
Longitudinal thickening of the ectoderm
Forms on the surface of the embryo, from head to tail region
Neural groove
Edges of neural plate fold
Neural tube
When folds of neural groove touch (day 21)
Closes first in future cervical spine region
Neuropores
When neural groove zips closed, rostraly and causally openings are left
Neural crest
Cells adjacent to neural tube separate from tube and remaining ectoderm
Soma
Cell body of a neuron
Somites
Spherical cell clusters of mesoderm formed parallel to the neural tube
Sclerotome
Anteromedial part of somite
Becomes vertebrae and skull
Myotome
posteromedial part of somite
Becomes skeletal muscle
AND
After embryonic stage, a group of muscles innervated by a segmental spinal nerve
Dermatome
Lateral part of somite
Becomes dermis
AND
after embryonic stage, the dermis innervated by a single spinal nerve
Motor plate
Ventral section of neural tube
Association plate
Dorsal section of neural tube
Ventral horn
Gray matter derived from the motor plate
Dorsal horn
Gray matter derived from association plate
Primary sensory neurons
Peripheral sensory neurons
Convey information from sensory receptors to association plate
Cauda Equina
Collection of lumbosacral nerve roots that extend inferior the the end of the spinal cord (resembles horses tail)
Filum terminale
Continuation of the Dura, pia, and glia connecting to the end of the spinal cord with the coccyx
Brain formation
Begins day 28
Hindbrain
Becomes medulla, pons, and cerebellum
Posterior forebrain
Becomes diencephalon
Anterior forebrain
Becomes telencephalon
