 Following the oral cavity, food enters the pharynx. Now, I'm back at this original picture because this will help us kind of visualize what exactly a pharynx is. By definition, a pharynx is a space that is utilized by both the digestive system, so food passes through a pharynx, and by the respiratory system, so air passes through a pharynx. It's a little bit of a mush in that definition because most of the time, food is not up here, but this is actually the nasopharynx. I'll write it down for you. The nasopharynx is superior to the soft palate. You have the nasal cavity, which is where air comes into your nose, and that's superior to the hard palate. Let's talk about those cavities in more detail when we get to the respiratory system. You also have the oropharynx, and I'm going to make it in... Let's see if I can get a nice bright yellow. We'll see if this works. The oropharynx, let's see, maybe I should be more specific to make sure that we do it exactly. Do you remember that my uvula was part of my soft palate? My oropharynx starts at the soft palate, and travels all the way down to the hyoid bone. Now, look at this. Here's my hyoid bone right there. Can you see how that looks like a bone? You can't see my yellow little arrow there. We'll go like that for my arrow. This structure right here is actually a bone, and if we had a sagittal section of the human head, we could totally tap the hyoid bone and feel that that's actually a bony structure that muscles are attached to. So this would be the oropharynx, and then we have one more pharynx that, again, is a shared space, and it's called the laryngeal pharynx, and the laryngeal pharynx goes from the hyoid bone, which is right here, to the cricoid cartilage, to the cartilage as part of your larynx or voice box, and again, we'll talk about that in more detail with the respiratory system, but this is the laryngeal pharynx. Laryngeal pharynx. Uh, what do you need to know? There are 17 muscles in your pharynx, and those 17 muscles are connected to a reflex, or the gag reflex. You can't really control if you stick your finger down your throat. Some people have more control over their gag reflexes than others, but if you start twiddling back there in your pharynx, you probably are going to activate the gag reflex, and the gag reflex, this is future, it's coming your way, but it's controlled by the vagus nerve, which is cranial nerve number 10. That's something that we will see when we get to the nervous system. For all intents and purposes, laryngeal pharynx is responsible for helping us swallow all those 17 muscles help us swallow, but really it's just a tube. Like, we're just on our way down. The next stop on our adventure is the esophagus.