Although we learn to recognise the visible signs of facial ageing – that become manifested in lines, wrinkles, contours and folds – most of us are less familiar with the underlying structure of the face that gives each of us our own unique characteristics.
Involving a complex web of bones, muscles and fat, we’ve compiled a basic overview of the facial structure, its function and how it changes through time to help better understand facial rejuvenation techniques and approaches.
Skeletal anatomy
Facial bone anatomy is both complex and elegant, forming the basis of our outward-facing features while serving a wealth of functions behind the scenes.
The key function of the human cranium is to protect the brain, its eight plates converging to house and safeguard the sense organs of smell, sight, sound and taste. The facial skeleton also provides a frame for the soft tissues of the face and facilitates eating, facial expression, breathing, and speech.
The principal bones of the face are the mandible (or jawbone), maxilla (or upper jaw), frontal bone, nasal bones and zygomatic bones (cheekbones). Except for the mandible, all of the bones in the skull are joined together by sutures – immovable joints formed by bony ossification, with Sharpey’s fibres (bundles of strong collagenous fibres) providing some flexibility.
The strong, U-shaped mandible houses the lower teeth and, as the only mobile bone of the facial skeleton, its motion is essential for mastication (chewing). The maxilla multi-tasks by holding the upper teeth, while also forming the roof of the oral cavity and wall and roof of the nasal cavity. The palatine bones form part of the mouth and nasal cavities and the vomer sits at the centre of nasal cavities. The small and fragile lacrimal bone at the inner orbit of the eye forms part of the tear duct system.
Muscular anatomy
A network of underlying facial muscles allow us to communicate, express emotions and convey thoughts, as well as perform basic functions such as blinking, chewing and speaking.
Many of the 43 muscles in the face are attached not to bones, but to each other or to the skin with which they interact. Oriented in bands, facial muscles are stimulated by the facial nerve and interact to produce expressions and individual nuances. The study of human facial movements has concluded that the six key expressions – anger, happiness, surprise, fear, sadness and disgust – among others, are an ingrained human trait rather than a learned response.
The eye area comprises a complex multi-layered structure. Layers of muscle hold the eyeball in place assisted by the orbital bone and orbital rim. Movement is regulated by the inferior oblique muscle and superior oblique tendon, and eyelids by the levator and orbicularis muscles.
These muscles are connected with fatty pads, predominately the malar fat in the cheeks and the sub-orbicularis fat below the eye. Orbital fat extends to the eyelids
and is limited by the orbital septum layer, which acts as a net. Upper and lower tarsal plates provide scaffolding in the eyelids, allowing them to retain their shape.
Skin
As the body’s largest organ and one of its most essential systems, the skin’s functions go far beyond the aesthetic. The skin regulates internal temperature; perceives external stimuli and transmits the information to the brain; protects from potentially harmful substances; and stores essential nutrients. Unlike some other areas, our facial skin is relentlessly exposed to the elements and, as a result, the skin on our face is always at risk of damage.
Where the skin on the soles of our feet is thick and durable, facial skin is lighter and thinner. However, this varies across the face. Whereas skin is thinner on the upper face, eye area and over the nose, it tends to be eshy in the lower face. Pigmentation, hair follicles, sebaceous and sweat glands are distributed in differing formations and the blood vessels below the surface in the epidermis may be visible to a greater or lesser extent.
Regardless of where skin is positioned on the body, it has e same structure of three layers: epidermis, dermis and subcutis (subcutaneous layer or panniculus adiposus).
Epidermis
The epidermis is the outer-most layer of the skin and continually renews and regenerates. Ultimately, all the cells in the epidermis originate from a single layer of basal cells in its basement membrane – these are called keratinocytes, which are stacked on top of each other to form several strata, melanocytes, and dendritic cells.
Keratinocytes develop in the basal layer and rise, losing their central nucleus and producing skin proteins called keratins and fats called lipids, before being shed from the surface of the skin as dead cells. As they move towards the surface of the skin, their form changes and they create distinct layers known – from the bottom up – as the basal layer, the spiny layer, granular layer, stratum and stratum corneum.
In the spiny layer, the keratinocytes make lipid fat cells which discharge as the cells move up through the granular layer, forming a moisture- carrying mortar around the basal cells, which are now called corneocytes. These effectively dead and attened cells form the protective outer layer of skin, which is worn away in a process known as desquamation. The entire process normally takes around 30 days – although sunburn, injury or cosmetically stripping the outer layer speeds the process.
The stratum corneum retains moisture in the lower skin layers, comprising up to 15 percent water. Moisture loss is regulated by the lipids, while dead cells are cleared away by skin enzymes.
Men tend to have thicker stratum corneum than women; they tend to have more collagen and produce more sebum, making the lipid layer of their skin thicker and the cell renewal process slower.
Melanocytes produce melanin, which contributes to skin colour and provides UV protection. Dendritic (or Langerhans) cells are involved in the immune system of the skin. They consume foreign materials that invade the epidermis and transfer out of the skin to stimulate an immune response.
Dermis
Between the epidermis and the subcutaneous fat layer lies the dermis, which contains connective tissue and houses the arteries, hair follicles, lymph vessels, sensation receptors, sweat glands and veins. This thicker dermal layer is composed primarily of collagen, which is responsible for the strength and elasticity of the skin. It is held together by a protein called elastin that is produced by broblast cells. The dermis also contains moisture-storing glycoproteins and hyaluronic acid, which have the ability to attract and bind hundreds of times its weight in water. Here, collagen and elastin production decline with ageing.
Subcutis (subcutaneous layer)
As the deepest layer of skin, the subcutis is made up of a loose network of fat and collagen cells. It acts as a protective cushion and helps insulate the body by monitoring heat gain and heat loss. The thickness of this layer can vary significantly in individuals and in different parts of the body. CBM
