(4.41)

Now that we’ve looked at the bony features of the nasal cavity, the paransal sinuses, and the nasopharynx let’s see what this region looks like in the living body. We’ll start with the entry to the air passage that forms such a distinctive feature of the face, the external nose.

The skin over the upper, bony part of the nasal framework is thin and mobile. The skin over the lower, cartilaginous part is thicker, and fixed to the underlying structures.

The openings which form the beginning of the air passage are the nostrils, also called the anterior nares. We’ll remove the skin from one half of the nose so that we can see the underlying structures. The edge of the bony opening for the nose, the piriform aperture, is here.

Here’s the nasal bone. The two nasal bones, united in the midline, form the bridge of the nose down to here. From here almost to the tip, the bridge of the nose is formed by the front edge of the septal cartilage, which we’ll see more fully in a minute. On each side the framework of the nose is formed by two slender pieces of cartilage, the lateral cartilage, and the alar cartilage.

The lateral cartilage is thin and flat. In front it’s continuous with the septal cartilage. The alar cartilage has two parts, the lateral crus, and the medial crus.

The lateral crus forms the curved outer framework of the nostril. The medial crus turns sharply backwards, ending here. Together the two medial crura form the framework of the lowest, most anterior part of the nasal septum, which is called the columella.

To get a good look at the nasal septum, we’ll divide the bone and soft tissues along this line, and remove the left side of the face. Here’s the nasal septum. Before we look at it let’s get oriented. Here’s the anterior cranial fossa. Here’s the bony palate, or hard palate, with the soft palate extending behind it. Here’s the oral cavity. Here’s the opening of the right nasal cavity. Behind it is the nasopharynx, which we’ll look at in a minute.

The nasal septum extends from here behind, to here in front. This small part of the septum is covered with skin. The rest of it is covered with this layer of mucous membrane. We’ll remove a small piece of the mucous membrane so that we can appreciate its thickness.

The highest part of the septum is the specialized olfactory area. It contains some of the fibers and nerve endings of the olfactory nerve, which are the sensory receptors for our sense of smell. The cribrifom plate, which the olfactory nerve fibers go through, is at this level.

Now we’ll remove all the mucous membrane from the septum so that we can see the underlying cartilage and bone.

This part of the septum is bone, as we’ve already seen. This part is formed by the septal cartilage. In this specimen there’s an unusual defect in the cartilage, here. In front, the septal cartilage forms the bridge of the nose down to here, then runs downward and backward to attatch to this bony prominence on the maxilla, the anterior nasal spine.

Now we’ll remove the whole of the nasal septum, so that we can see the lateral wall and floor of the nasal cavity. The inside of the nostril, up to the lower border of the lateral cartilage which is here, is called the nasal vestibule. It’s lined with skin. The rest of the nasal cavity is lined with mucous membrane.

Here are the conchae, superior, middle, and inferior. The mucous membrane that covers them is richly supplied with mucous glands, and with blood vessels. The complex surfaces of the conchae have imporatant functions in humidifying the inspired air, and warming it. This olfactory area, like the corresponding area on the septum, contains olfactory nerve fibers and nerve endings.