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We're gonna start with inflammatory disease, and

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in order to understand this better, we have to

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know the normal drainage of the paranasal sinuses.

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So when we are considering the frontal sinus,

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the frontal sinus drains into the frontal

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ethmoidal recess or the frontal recess.

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Terms are used interchangeably, and from

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there into the middle meatus. I will define

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these—the anatomy here in just a moment.

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The anterior ethmoid complex drains through

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the hiatus semilunaris into the middle meatus.

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And then the posterior ethmoid complex

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and the sphenoethmoidal goes through the

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sphenoethmoidal recess for its drainage.

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And all of these go to the back of the

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throat, where the mucus is swallowed into

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the pharynx. For the maxillary sinus,

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the flow is through the maxillary sinus

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ostium into the infundibulum, and then to the

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middle meatus, and then back to the pharynx.

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So let's look at this anatomy on a diagram.

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This is a coronal CT scan using wide

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chest or pulmonary windows in order to

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see the air within the paranasal sinuses.

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It's not devoted towards looking at the bone,

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however, it very nicely shows the anatomy

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of the paranasal sinuses that is important.

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So the "O" that we are looking at

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here in the maxillary antrum

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is the ostium of the maxillary sinus, and the flow

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of mucus goes through the ostium into this area,

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which has been labeled "INF" for infundibulum. Above

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the infundibulum, where the black arrow is, is

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an area known as the hiatus semilunaris, and it's

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just below an ethmoid air cell known as the bulla.

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The asterisk that you see resides

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between the middle turbinate

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and the uncinate process.

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This is the uncinate process.

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And the uncinate process defines the infundibulum

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laterally from the area where the

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asterisk is, which is the middle meatus.

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The flow of mucus from the maxillary

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sinus goes through the ostium into the

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infundibulum, back along the hiatus semilunaris,

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and then from there to the middle meatus.

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Let's look on the image to the right here.

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And what we see is the "B" for the ethmoidal bulla.

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That is the air cell just above the

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hiatus semilunaris and the infundibulum.

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And it's a very important air cell because, depending

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upon its size and its configuration, it may narrow

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the areas of drainage for the maxillary sinus.

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Here we have the frontal sinus, and what you notice

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is that the frontal sinus has an area where it drains.

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Through this asterisk into the frontal

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recess or frontal ethmoidal recess, and it

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too goes into the middle meatus for drainage.

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I wanna point out a little bit more anatomy

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on this slide, and that is the turbinates.

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So the turbinates include the inferior

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turbinate and the middle turbinate, and

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you can see that the middle turbinate

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forms the medial border of the

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middle meatus and the frontal recess.

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The middle turbinate has two attachments.

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One is to the cribriform plate at the skull base,

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and there is a second attachment that we will

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see shortly, that goes to the orbital wall, which

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is known as the basal lamella or ground lamella.