In the human body, what does the orbital cavity contain?
And the answer: eyeball.
Also known as the eye socket, the orbit is a cavity in the skull that contains the eyeball, eyelids, cranial nerves, muscles, and more. Seven different bones make up the socket, which is shaped like a cone.
The bones that comprise your head are some of the most delicate and intricate of your entire body. While the term "skull" is used to refer to the casing which protects your brain more generally, there are actually 29 bones that make up this structure. The orbital cavity is just one piece of the puzzle. While the cavity itself is not an individual bone, its boundaries are formed by the frontal, maxilla, zygomatic, sphenoid, ethmoid, lacrimal and palatine bones. The cone-like shape of the orbital cavity fits between these bone structures towards the back of your head. You can even feel your orbital rim for yourself just to the left and right of your eyes.
Interestingly, your bones are nearly as dynamic as the organs in your body. Contrary to popular belief, bones aren't dried, immovable structures that exist simply to give your body structure. Instead, they're technically organs themselves. Comprised of multiple types of tissue, the inner workings of bone structures are responsible for the creation of red blood cells and storage of calcium. Bones are made of active connective tissue that breaks down, regenerates and repairs itself throughout your life. In fact, humans essentially generate an entirely new skeleton every 7 to 10 years!
As such, bones (especially those which make up the skull) can be greatly affected by different conditions. In 2015, astronauts Scott Kelly and Mikhail Kornienko spent an entire year on board the International Space Station to test the endurance of the human body in microgravity. The pair was required to exercise extensively 6 days a week to combat the intense, weakening effects of living in an environment without gravity – an effect which most prominently can be understood in relation to bone mass. In space, a human suffers 1 to 2 percent bone loss every month. That's about as much as an average elderly individual loses per year. Wow!
Read more about the effects of space on bones and their associated qualities here.