Answer to challenge 4:
Vagus nerve ✔️
I made it quite easy by adding the last clue which was the biggest giveaway. Since seeing most people struggled with day 3. I decided to have some mercy and make it more easier. Ease after difficulty lol.
– Sister A (she messaged with the answer apart from the blog comment)
– The miracle of life 68 (blog)
Mention of the vagus nerve was made in the chapter below
And here are 2 illustrations
It was discussed during the initial chapters of the blog…