Bones of the Nasal Cavity
Fig. 34.1 Skeleton of the nose
The skeleton of the nose is composed of an upper bony portion and a lower cartilaginous portion. The proximal portions of the nostrils (alae) are composed of connective tissue with small embedded pieces of cartilage.
Fig. 34.2 Bones of the nasal cavity
The left and right nasal cavities are flanked by lateral walls and separated by the nasal septum. Air enters the nasal cavity through the anterior nasal aperture and travels through three passages: the superior, middle, and inferior meatuses (arrows). These passages are separated by the superior, middle, and inferior conchae. Air leaves the nose through the choanae, entering the nasopharynx.
Paranasal Air Sinuses
Fig. 34.3 Location of the paranasal sinuses
The paranasal sinuses (frontal, ethmoid, maxillary, and sphenoid) are air-filled cavities that reduce the weight of the skull.
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Table 34.1 Opening of nasal structures into the nose |
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Nasal passage |
Sinuses/duct |
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Sphenoethmoid recess |
Sphenoid sinus (blue) |
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Superior meatus |
Posterior ethmoid sinus (green) |
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Middle meatus |
Anterior and middle ethmoid sinus (green) |
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Frontal sinus (yellow) |
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Maxillary sinus (orange) |
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Inferior meatus |
Nasolacrimal duct (red) |
Fig. 34.4 Paranasal sinuses
Mucosal secretions from the sinuses and nasolacrimal duct open into the nose.
Fig. 34.5 Bony structure of the paranasal sinuses
Coronal section, anterior view.
Clinical
Deviated septum
The normal position of the nasal septum creates two roughly symmetrical nasal cavities. Extreme lateral deviation of the septum may result in obstruction of the nasal passages. This may be corrected by removing portions of the cartilage (septoplasty).
Sinusitis
When the mucosa in the ethmoid sinuses becomes swollen due to inflammation (sinusitis), it blocks the flow of secretions from the frontal and maxillary sinuses in the osteomeatal unit (see Fig. 34.4). This may cause microorganisms to become trapped, causing secondary inflammations. In patients with chronic sinusitis, the narrow sites can be surgically widened to establish more effective drainage routes.
Neurovasculature of the Nasal Cavity
Fig. 34.6 Nasal septum
Fig. 34.7 Arteries of the nasal cavity
Left lateral view. Note: The venous drainage of the nasal cavity is into the anterior facial and ophthalmic veins.
Fig. 34.8 Lateral nasal wall
Clinical
Noseble eds
Vascular supply to the nasal cavity arises from both the internal and external carotid arteries. The anterior part of the nasal septum contains a very vascularized region referred to as Kiesselbach's area. This area is the most common site of significant nosebleeds.
Fig. 34.9 Nerves of the nasal cavity
Left lateral view.
