Ch 8 Flashcards
3 developmental stages in utero
Pre-embryonic
Embryonic
Fetal
T/F: embryonic stage lasts from conception to day 14
F: pre-embryonic
(embryonic: day 15 to end of 8th week)
Fetal stage is from the ___ week to ___
8th
birth
Ectoderm (outer cell layer of embryo) develops into
Sensory organs, epidermis, NS
Mesoderm develops into
Dermis, musc, skel, excretory and circulatory systems
Endoderm becomes
Gut, liver, pancreas and respiratory sys
T/F: cell layers = endoderm, mesoderm, ectoderm (in-out)
T
Formation of neural tube (days 18-26)
Neural plate (thickening of ectoderm)
On surface of embryo, plate extends from head to tail region
Edges of plate fold to create neural groove
Day 21, when folds touch, neural tube= formed
Tube closes first in future cervical region
Groove rapidly zips closed rostrally and caudally leaving open neuropores (open ends)
T/F: neural tube closes similarly to 2 way zipper (closes in middle)
T
Inf part of neural tube becomes ___, sup part becomes ___
Spinal cord
Brain
T/F: dermatome is an embryonic section of somite, after embryonic stage group of musc innervated by segmental spinal nerve
F: myotome
T/F: dermatome is the area of somite that becomes dermis, after embryonic stage dermis = innervated by single spinal nerve
T
Why does the adult spinal cord end @ L1, L2 vertebral lvl?
As fetus matures, spinal column grows faster than cord
What is the end of the spinal cord called?
Conus medullaris
What are the nerve roots that extend inferior to the end of spinal cord?
Cauda equina
T/F: the mesencephalon is synonym for midbrain
T
The hindbrain differentiates into
Medulla, pons, cerebellum
T/F: midbrain retains it name throughout development
(central canal becomes cerebral aqueduct in midbrain, connecting 3&4 ventricles)
T
The post region of forebrain stays near the midline and becomes
Diencephalon
Ant region of forebrain becomes
Telencephalon
Spina bifida is a neural tube defect that results when the inf ___ does not close
(developing vertebra do not close around incomplete neural tube –> bony defect @ distal end of tube)
Neuropore
Spina bifida ___ occurs if the neural tissue does not protrude through the bony defect, spinal cord func normally
Spina bifida occulta
Spina bifida occurs before, during or after birth
Before
3 types of spina bifida cystica
Meningocele, myelomeningocele, myeloschisis
