Lip anatomy and injection
The wet dry border of the upper and lower lip is a common site of injection. However, many practitioners prefer to use a needle in this region, and it would be very important to know the vascular risks. In this particular specimen, you will notice that the inferior labial artery is lying very superficial, just under the mucosa but in the posterior aspect. You will see, therefore, that inadvertent injection in this region could quite easily get the needle inside this vessel. You will also see that the needle is considerably thinner, or more narrow, than the vessel itself. Accordingly, it would not be difficult to get our needle within this vessel, leading to occlusion and necrosis. Therefore, if we are going to inject the lower lip, especially in the posterior region, it would be wise to use a cannula. Also, we can see the same scenario in the upper lip; if we reflect the skin back, bearing in mind that the muscle has been dissected out to show the vessels, the superior labial artery lies posterior and just under the mucosa. Therefore, when injecting the lips, if we are anterior and superficial then we are relatively safe, but for any injection that is posterior it would be wise to use a cannula.
Perioral anatomy and injection
In this video, let’s explore the vascular anatomy when treating the perioral region. In this specimen, we have reflected the skin back and can see the cervical platysma, and also this pyramidal shaped muscle, which is the DAO, or the depressor angularis oris. The structure I am pointing to now is the facial artery as it is dipping in and out up to the modiolus. It then gives off this structure, which is the inferior labial artery, and we will also have a superior labial artery that supplies the upper lip. If I extend the skin, bearing in mind that in this region we have dissected the muscle out so we can see the vessels, we will see the superior labial artery has a posterior course lying deep to the muscle. As the vessel is deep, if we inject the anterior aspect of the lip, as long as we are just under the mucosa in a superficial plane, this will be a relatively safe location for our injection. If I reflect the skin back, we can see that the product will be placed just under the mucosa and there will normally therefore be a muscle layer between the product and the deeper lying vessel. When we want to inject in the deeper plane, as we may do if we want to get an eversion of either the upper or lower lip, it would be very wise to use a soft tissue cannula, however, one point of safety to note is that the cannula can inadvertently get inside the blood vessel. Have a look here at how, despite being a 25 gauge cannula, it is actually more narrow than the superior labial artery. Therefore, just because you are using a cannula, it does not mean that you cannot have a vascular accident.