In this video, we are going to examine the structure of the nose. The key layers of the nose that are of interest to us are the skin, the nasal muscles, the fibro fatty layer, the bones, and the cartilage. Running within these layers we also find the blood supply. Within medical aesthetics, there are a number of anatomical points that can help to guide us, including those use in cephalometric analysis which will be covered in another video. The ones we can see shown here are the radix, the nasal tip, the columella, the subnasali, the ala, and finally the anterior nasal spine.
There is considerable interplay between the muscles of the nose which we shall now explore. The levator labii superioris alaeque nasi arises from both the maxilla and the nasal sidewall. It then inserts into the orbicularis oris and the nasal alar. When it contracts, it causes elevation of the nose and enhances the nasolabial fold. The transverse nasalis originates from the maxilla and inserts into the nasal bone. It causes compression of the nostrils when it is active. The compressor naris also arises from the maxilla and inserts into the aponeurosis. Again, contraction causes compression of the nostril. The dilator naris is another muscle that originates from the maxilla, but during smiling it contracts to open the nostrils. The depressor septi nasi arises from the incisive fossa of the maxilla and inserts into both the nasal septum and the back of the ala. When smiling occurs, it contracts to lower the tip of the nose and shorten the upper lip, compared to their resting position.
The bony support for the nose comes from the area surrounding the piriform aperture. As we age, this widens and the nose loses support, leading to widening of the ala and plunging of the tip. We will now look at the blood vessels within the nose. It receives its blood supply from a number of different vessels, some of which we will examine here.
The facial artery enters from below and forms as a branch from the external carotid artery. At the level of the nasal ala, we find the sub-nasal artery, a lateral nasal artery, and the angular artery. The superior labial artery has columella branches which feed into the tip of the nose. The ophthalmic artery brings in a blood supply from above by way of the dorsal nasal artery. We should note that blood vessels tend to be lateral and superficial within this region, and many anastomosis between the different vessels can occur. The blood vessels in this region are particularly important due to their connections and their origins. Dermal filler inadvertently injected into the blood vessels can cause blindness due to the connections with the ophthalmic artery. The video reviewing the mechanism of filler blindness contains more information on this important topic. At the apex of the nose, skin is relatively thin and has a low pressure. As we proceed downwards the skin becomes thicker until it reaches its thickest point with the highest pressure at the tip.
The goal when we are treating this region is to influence different facial angles, which in this case include the frontonasal angle and the nasolabial angle. We can also inject over the anterior nasal spine to elevate the tip of the nose. As we consider the anatomy of the nose, we can see that the safest injection sites for dermal filler lie in the midline and at a deep level. Injecting here ensures we avoid the blood supply within this region. The tip of the nose is a particular ‘danger zone’ because of the thick tissue and high pressure at this point.