ventricles
The empty space inside a tube is called the lumen. It is the hollow part through which fluid or air can flow.
The hollow core of a needle is called the lumen. It is the open space inside the needle through which fluids are drawn or injected.
marrow
a cavity,opening,or space within somethingwhen something is hollow t has nothing inside it (when a tree is hollow it is empty)
lumen
Hollow.
The spinal-canal which surrounds the spinal cord .
The hollow space behind the nose is called the hot dog sinus
a cavity,opening,or space within somethingwhen something is hollow t has nothing inside it (when a tree is hollow it is empty)
The urinary bladder is a hollow organ, which means it has empty space inside that can expand to store urine.
The word hollow is an adjective. It means to have an empty space inside.
The vertebral canal is the hollow space within the spinal column that houses the spinal cord, while the foramen are openings in the vertebrae through which nerves pass.