There is some recent news that Rory Markham fought with a 'collapsed lung' at UFC 95.

Now there needs to be some nuanced dissection of this diagonsis before people start raving that Markham is a beast that fought with only one lung.

A collapsed lung is medically described as a pneumothorax and affects breathing.  Respiration operates by maintaining pressure gradients that allow air to move from a high gradient to a low gradient. Changes in volume within the thoracic (chest) cavity is what allows for the change in pressure to precipitate the movement of air. Thus inhalation is expanding the cavity to increase the volume and lower the pressure gradient, causing air to travel into the lungs. Exhalation is the shrinking of the cavity, to decrease the volume, thus increasing the pressure, which causes air to flow out of the lungs. Muscles, like your diaphragm and intercostals, are actually used in changing the volume of the thoracic cavity not contracting 'on' the lungs to facilitate breathing.

A pneumothorax can be a full or partial collapse of the lung and is usually caused when air gets in between the lung and chest wall. The presence of air within the wall, changes the pressure within the thoracic cavity making it more difficult to breathe due to the disruption of the pressure gradients.

Rory Markham clearly suffered a pneumothorax, he was X-rayed and stayed in the hospital for two days for observation. Of course affected his fighting ability in some way though the fight was short so by how much is an unknown.

Now there are varying degrees of pneumothorax, as pictured below. These degrees of injury indicate what kind of treatment is required.

Since Markham did not undergo any surgery or a procedure and was only observed for two days, it indicates the injury could heal on its own. Making it most likely a small pneumothorax. It is possible to suffer a small pneumothorax from stretching. 

This story appears to be the red flag, "oh my god, he fought with one lung!" injury  that is making its way across the internet.

When fighters make this kind of announcement regarding injuries suffered, but offer no details of the severity or degree, it is our job to say wait a minute, this isn't making a whole lot of sense.

Remember when Jamie Varner was complaining about his 'detached retina'? That isn't the type of injury that you can just waltz into the optometrists office a week after it occurred, at least if it is was as severe as Varner was describing.

Look, we saw what happened with Amare Stoudemire when he had a detached retina. Immediate surgery and out for the rest of the regular season. Not quite on par with Varner's injury.

It is important to remember that when these fighters describe an injury to take it with a grain of salt. They are not medical professionals nor are they describing the severity of the injury they are classifying. It's akin to saying, "I have a broken toe" when the damage is small break at the end, versus saying "I have a fractured third metatarsal which will require screws in order to set the bone to heal."

It is in the specifics and description of an injury, not some medical term, that we discover what type of damage has actually been done to a fighter.