Jawline anatomy


In this video, I want to look at the key neurovascular structures when contemplating jawline treatment. If I begin by reflecting the skin backwards and also take up the superficial fat, we will notice that we have the deep buccal fat. I can reflect this, and this allows us to see the facial vein as it courses down just anterior to the masseter muscle. Also, at the anterior aspect of the masseter, we see another very important structure, which is the facial artery, a branch of the external carotid artery. The facial artery has a tortuous course, you will notice that it comes up and down like a dolphin coursing through water, and at the modiolus it is slightly deep to the muscle layers. The final structure that we have in this area is a very important nerve, and this is the marginal mandibular branch of the facial nerve.


Therefore, in this region we have the facial vein, the facial artery, and the marginal mandibular branch of the facial nerve. These three key structures are often found just anterior to the masseter, and they are particularly prone to damage, especially if we use a needle. Accordingly, if we are contemplating any jawline treatment, especially posterior to the jowl, it is important to use a cannula and also treat in a superficial level, thereby avoiding damage to these structures.


Facial artery anatomy


In this video, we want to explore an alternative course of the facial artery. We know that the supply of the facial artery in the face is subject to considerable variation, so if we reflect the skin and subcutaneous fat back we can see the artery here lying just anterior to the masseter muscle. In this particular specimen, we see that the inferior labial artery and the superior labial artery have been given off the main trunk of the facial artery much earlier. In the majority of cases we would find these vessels given off closer to the modiolus. The facial artery itself continues towards the alar fossa, usually lateral to the nasolabial fold, and at the base of the fold it is relatively deep. However, as it ascends it becomes increasingly more superficial, and it is important to bear this in mind when we inject any structure close to the nasolabial fold. We can track the facial artery here just below the subcutaneous fat, and in this specimen we can see two vessels that supply the nose. We can first see the subnasal artery, which is the smaller vessel, and we can also see the lateral nasal artery here, which is often found superficially in the alar groove. In this particular specimen, this is where the facial artery terminates. We would often find the facial artery running along the nasal sidewall, and we would conventionally call this the angular artery, however, in this specimen, this is terminal. It is important to bear this variation in mind because an embolic phenomenon in a patient like this may result in substantial loss of tissue to the nose.


Jaw injection


In this video, we want to have a look at the jawline and the injection filler techniques that we can use to define the jawline. If we start by reflecting the skin back, the first thing we see is the superficial or subcutaneous fat layer. Remember, with advancing years we can get an accumulation of fat deposits in this area which lead to a blunting of the jawline. Although this looks like one confluent layer, these are individual fat compartments which are bounded by septae. When we peel back the subcutaneous fat we can then have a look at the SMAS and muscle layers.


In this region, we will start most medially by looking at the mentalis fibres. Lateral to the mentalis we can see the depressor labii inferioris fibres, and in this particular specimen we can see the structure just below the muscle fibres, which is the inferior labial artery. This is a vessel that can have a very variable course, and may come off the facial artery lower or higher than anticipated. Medial to the DLI, we have this triangular shaped muscle, the depressor angularis oris, which has a narrow insertion and a wider origin on the mandible. This very important structure highlighted with the plastic cards is the facial artery which you can see is coursing up then underneath the zygomaticus major muscle and then heading towards the modiolus where it will give off the superior labial artery. The facial artery itself crosses the neck at a deep level anterior to the masseter muscle.


Let’s now have a look at how we would inject the jawline to improve definition in this area. Because of risk to the underlying structures, mainly the facial artery, facial vein, and marginal mandibular branch of the facial nerve, it is vital to use a cannula when augmenting this region. The injection depth is superficial, and ideally we want to be subdermal or in the subcutaneous fat. We use a soft tissue cannula and we deposit the product in linear threads to add definition to the jawline. Let’s now see where the injected product is sitting. I am reflecting the skin back to reveal the subcutaneous fat, and in a living patient it is entirely possible that we would inject in that subdermal region. Then, I reflect off the subcutaneous fat and we see the product between the subcutaneous fat and the SMAS. Because this is a pre-dissected specimen, the product is a little deeper than we would inject in a living patient, however, you will notice that it is still above the deep vascular structures.