Fetal development, gastrulation and embryonic disc
Human embryogenesis is much more complicated than the more general and simplified picture given in your 1st figure.
For details, please study http://en.wikipedia.org/wiki/Human_embryogenesis

To point out the most distinctive features which might have led to your confusion:


Before gastrulation, the blastocyst cavity is formed.
Only the inner cell mass undergoes gastrulation.
Mesoderm forms quiet late and spreads, thereby also forming the chorion as well as the amnion.
The embryo itself is formed from a subset of all embryogenetic cells. This is shown in your 2nd figure, part C and D. Yet, tissues are still going to spread such that the final ectoderm as well as mouth and anus will be formed.