 We'll do a very brief review of anatomy, just get some reference points that you can use to orient yourself as you're going through the images. And then we'll start in on the pathology, we'll talk about congenital disorders of the inner ear, we'll talk about inflammation in the middle ear, we'll briefly talk about trauma and then we'll talk about some specific clinical scenarios, just some brief discussions of inner ear anatomy. The cochlea, when you're figuring out where you are in the cochlea and orienting yourself, there's a series of food analogies. Radiologists love food analogies and the inner ear is no exception. But then when you're looking at the vestibule and the semi-circular canals, posterior to the internal auditory canal, we're going to be looking at them in predictable orientations to talk about which of the semi-circular canals we're looking at. So we're going to run through the cochlea and talk about the food analogies. If you're down at the lowest cut of the cochlea and you're looking at the basal turn of the cochlea, that has been likened to a banana. It looks more like a gherkin pickle to me, but people call this the banana. You come up a little bit and now you can see not only the basal turn of the cochlea, but now you can see the upper turns of the cochlea separated by bone. This has been likened to a stack of pancakes. If you keep coming up, now you've lost the basal turn of the cochlea, you're above the basal turn of the cochlea, and you're seeing the upper turns of the cochlea separated by the scaler. There's the medialis down the center. Now it's likened to a cluster of cherries, the upper turns of the cochlea. Now we've moved to coronal plane now. Here's a coronal cut. The coronal cut has the snail. I'll let you decide whether that is a food analogy or not. The snail has the curved shell that is the cochlea, right? But there's eyes too. It's not just the snail's shell. There are also two eyes up there. And those two eyes are two different parts of the facial nerve. It is the labyrinthine section of the facial nerve as it swings forward and then hits the genic that ganglion comes back. And now it is the tympanic segment. So both the labyrinthine and the tympanic segments of the facial nerve, those are the two eyes of the snail. Now turning towards our semicircular canals, we're back behind the internal auditory canal. And we orient ourselves by finding the vestibule first and then finding the semicircular canals that come off of them. So the lateral semicircular canal is the easiest, right? It's like a ring and there's like a signet ring where the vestibule is the stone. And the curve of the ring is the lateral semicircular canal, very easy to find on axial images. Now what about the posterior semicircular canal? As predicted, it's posterior to the vestibule. And you can see it's swinging up and then swinging across as it comes to the top. The superior semicircular canal, if you come up towards the top of the temporal bone, you can make out both the anterior and posterior limbs of the superior semicircular canal, so it's easy to find near the top because of those two limbs. Now I want to emphasize that the posterior and superior semicircular canals come together. They join together before they return to the vestibule as a common cruise, shared by those two semicircular canals. And then of course behind the vestibule, this is the vestibular aqueduct. It's very difficult to put on one axial image. It looks best on an oblique image, but it will run from the back of the vestibule to the posterior fossa. One other item I think is really worth pointing out here is the sub-arcuate canal, sometimes called the petromastoid canal. This normal canal runs right underneath the arch of the semicircular canal. And this can be accidentally mistaken for a fracture, but it's a normal structure and it carries the sub-arcuate artery. And so sometimes it's larger, sometimes it's smaller. Do not mistake this for pathology. This is a normal structure, the sub-arcuate canal.