the neck
The hollow part of a bird is called the airsac.
barg
If the curve is part of the circumference of the circle, it is called an arc.
They are called threads
called a What_type_of_fossil_is_found_in_a_hollow_place_shaped_like_an_organism.
The hollow at the base of the throat is called the supra-sternal notch.
marrpw
I do not know, so don't ask me.
The empty space inside a tube is called the lumen. It is the hollow part through which fluid or air can flow.
The middle hollow part of your hand is called the palm. The palm is the central region of the hand located between the fingers and the wrist, and it is used for gripping, holding objects, and performing various tasks.
Hollow dude, its part of your intestines, think about it...
Renji? No, he isn't part hollow so he can't get a hollow mask.