Anatomy

Facial Anatomy

When considering the anatomy of the face for rejuvenation with injectable treatments it is very helpful to think of it in its entirety as a three-dimensional structure that consists of five unique layers running superficial to deep. This is important, so that we know which structures we are aiming to treat & the success we will gain from each approach.

We must remember, that the ageing process effects not only the most visible part of our face, the skin, but also other intrinsic factors that are at play including deep fat layer loss as well as loss of muscle laxity, ligament and bone deterioration which dramatically accelerate ageing.

Ligaments

There are several ligaments that run through these tissue plane, from deep to superficial. The true retaining ligament run from the periosteum through the SMAS layer to insert into the dermis. These include the orbital retaining ligament, the zygomatic cutaneous ligament and the mandibular ligament. Several smaller ligaments are also present which can be described as condensations of fascia which run from the SMAS layer superior to the skin. The role of these multiple myocutaneous ligaments is to allow the transmission of movements of the muscles of facial expressions to the skin.

Arteries

Arterial Blood Supply

The face contains two main arterial blood supplies. One arising from the external carotid artery system and one arising from the internal carotid artery system.

The external carotid artery gives rise to the facial artery which crosses the mandible, entering the face at the junction between the posterior one third and the anterior two thirds of the body of the mandible. This also corresponds to the anterior border of the masseter muscle and this can be palpated at this point as well as being identified by a facial artery notch that runs inferiorly along the edge of the mandible. This artery runs underneath the SMAS layer and traverses superiorly and medially towards the corner of the lip before giving rise to an inferior labial and superior labial artery, and then continuing in the deep nasal labial fat as the nasolabial artery. This continues along the side of the nose, as the angular artery, and gives rise to an alar branch to supply the skin over the ala of the nose and a lateral nasal branch to supply the skin of the lateral nose.

A further branch of the carotid artery is its terminal branch, the superficial temporal artery which divides into two main branches and supplies the skin of the temporal and forehead area.

The second main supply to the face arises from the internal carotid artery which gives rise via its various branches to the supraorbital and supratrochlear artery. As the facial artery makes its way from the mandible notch to the oral commissure, it branches to the inferior labial artery and the superior labial artery and continues towards the nasal alar and meets the angular artery.

The inferior labial artery comes off the facial artery and penetrates the orbicularis oris and runs a tortuous course along the inferior “wet/dry” border of the lips.. It supplies blood to the lower lip and mucous membrane. The artery anastomoses with the inferior labial artery on the opposite side.

The superior labial artery is larger than the inferior artery and runs along the inferior “wet” border. It has 2-3 branches towards the nose including the alar branch and nasal septal.

Difference between Arteries, Veins and Capillaries

Blood presentation 1

Danger zones when injecting:

Glabella
Temple
Nose
Perioral Area (Lips)
Infraorbital area region
Nasolabial Folds

Veins of the face have no valves which means free retrograde flow therefore-

Higher risk of infection
Embolisation leading to blindness
Orbital and central nerve infection (Orbital Cellulitis and Cavernous Sinus Thrombosis)

Position of the Facial Nerves

There are 12 Cranial nerves that control the muscles in the head and neck and carry nerve impulses (sensory information) from sense organs to the brain.

The olfactory nerve transmits sensory information to your brain regarding smells
The optic nerve is the sensory nerve that involves vision.
The oculomotor nerve has two different motor functions: muscle function and pupil response.
The trochlear nerve controls your superior oblique muscle. This is the muscle that’s responsible for downward, outward, and inward eye movements.
The trigeminal nerve is the largest of your cranial nerves and has both sensory and motor functions.
The abducens nerve controls another muscle that’s associated with eye movement. This muscle is involved in outward eye movement. For example, you would use it to look to the side.
The facial nerve provides both sensory and motor functions, including: moving muscles used for facial expressions as well as some muscles in your jaw: providing a sense of taste for most of your tongue: supplying glands in your head or neck area, such as salivary glands and tear-producing glands; communicating sensations from the outer parts of your ear.
Your vestibulocochlear nerve has sensory functions involving hearing and balance.
The glossopharyngeal nerve has both motor and sensory functions.
The vagus nerve is a very diverse nerve. It has both sensory and motor functions.
Your accessory nerve is a motor nerve that controls the muscles in your neck. These muscles allow you to rotate, flex, and extend your neck and shoulders.
Your hypoglossal nerve is responsible for the movement of most of the muscles in your tongue.

Salivatory Glands

Five nerve branches divide within the parotid gland. There is a structure of lymphatic drainage within the area.

Langers Lines

Langer’s lines, Langer lines of skin tension, or sometimes called cleavage lines, are topological lines drawn on a map of the human body. They correspond to the natural orientation of collagen fibres in the dermis and are generally perpendicular to the orientation of the underlying muscle fibre.

The Skin

The skin is the largest organ of the body.

Cells have an average life span of 19 – 34 days.

The average person is covered by 2 ½ square yards of skin that weighs around 9 pounds.

The average human grows about 1000 completely new outer skins during a lifetime.

Red blood cells wear out at a rate of 3 million every second, requiring the body to make over 200 billion new ones every day.

The body’s entire supply of red blood cells is completely renewed every four months.

Blood platelets last only 7-10 days in the body. They are one of the shortest-lived elements in the human body.

Skin has two major tissue layers, The Epidermis, a thin layer of nonvascular tissue and the dermis, a dense layer of vascular connective tissue the subcutaneous layer (below the dermis) is a thick layer composed of fatty connective tissue that varies in thickness in each person.

A unique characteristic of the epidermis is its ability to regenerate tissue continuously. This process of shedding and renewing and renewing of epidermal tissue is called desquamation, taken from the Latin ‘desquamatous’ that means to scale off.

The outer layer of healthy skin is moist and approximately 10% water.

Intercellular cement is the lipid substance between the cells of the epidermis that keep the skin from dehydrating and helps to shield the skin from aggravating substances.

The layers of the epidermis have no blood vessels.

In order of their distance from the surface:

Stratum Corneum: Horny Layer: The outer layer of skin. This layer is the thickest of the epidermal layers and is exposed to the outer elements. The cells in this layer are dry and flat. This layer may have between 18-23 layers of flat dry cells that are cemented together by lipids, peptides, sebum and ceramides.

Stratum Lucidum: Is only present on the palms and soles of the feet. Thickness may vary from 0.5 to 0.8MM on the palms and soles of the feet and can be less than 0.1mm on the eyelids.

Stratum Granulosum: In this layer the lipids separate from the keratin (a non-living substance), ands cells lose a considerable amount of fat and moisture. These cells are approximately 80% keratin and less than 20% water.

Stratum Spinosum: This layer is several layers thick and flattens out as it rises upward. It is called the spiny or prickle cell layer due to the spiky appearance of the cells.

Stratum Germinativum: The Basal layer is the only living layer of the epidermis where mitosis takes place. Mitosis is the process by which body cells divide to form two identical cells. This layer of skin does not have any blood vessels in it. Melanin is also in this layer.

Layers of the Dermis

Papillary Layer: This Layer of skin is directly below the epidermis.

Reticular Layer: This Layer contains the following:

Nerves.
Lymph Vessels.
Oil Glands.
Elastin.
Blood Vessels.
Hair Follicles.
Sweat Glands.
Fat Cells.
Arrector pili muscles.
Collagen

One Square inch of skin contains:

9,500,000 Cells
65 Hairs
19-20 Yards of Blood Vessels
13 Sensory apparatuses for cold
19,500 Sensory cells at the ends of nerve fibres
1,300 nerve endings to record pain
650 Sweat glands
95-100 Sebaceous glands
78 sensory apparatuses for heat
78 yards of nerves
160-165 pressure apparatuses for the perception of tactile stimuli.

Why does the skin age and what happens when it does?

How our skin ages is dependent on many influencing factors: lifestyle, diet, genetics, sun exposure & our own personal habits. For instance, smoking produces free radicals that make once-healthy oxygen molecules overactive and unstable. Free radicals damage our skin cells, breaking down our collagen and elastin and producing lines & wrinkles. In addition, primary factors contributing to wrinkled, liver spotted skin include the normal ageing process and extensive unprotected exposure to the sun (photo aging) and pollution. The loss of subcutaneous support (fatty tissue between your skin and muscle). Other factors that contribute to aging of the skin include stress, gravity, daily facial movement, obesity, anorexia and even more basic influences such as sleep position.

As we age skin tone & texture changes significantly:

Skin becomes rougher & uneven in texture
Skin develops lesions such as benign tumours.
Skin becomes slack due to the loss of the elastic tissue (elastin) in the skin with age causes the skin to hang loosely.
Skin becomes thinner & more transparent. This is caused by thinning of the epidermis (surface layer of the skin)
Skin becomes more fragile & sensitised. This is caused by a flattening of the area where the epidermis and dermis (layer of skin under the epidermis) come together.
Skin bruised easier. This is due to thinner blood vessel walls.

Skin Facts

The skin guards the body from injury and bacterial invasion

The perceived colour of a person’s skin depends on the intensity of the state of contraction or dilation of the superficial vessels and on the extent of oxygenation of the blood.

Our skin has a limited capacity for absorption.

Freckles are an uneven distribution of melanin in the epidermis.

Skin is about 1mm thick on your eyelids, 3mm thick on the palms of your hands and the soles of your feet and about 2mm thick everywhere on the body.

The nerve endings are small and separate so that sensation is distributed not uniformly but in small areas. Individuals who are insensitive to pain have defective development of certain nerve structures.

When cells are injured, histamine (a chemical that dissolves protein) is released and these irritate the sensory nerve endings to cause varied degrees of discomfort.

When ice is applied to the skin the capillaries constrict, less blood and histamine flows and pain is alleviated.
When the skin is stroked firmly, the contractile cells of the vessels are mechanically stimulated, and capillary constriction produces immediate blanching. When these cells relax, the vessels dilate, and redness appears that flares to a small distance from the actual site of the stimulus. The flare depends on the integrity of nerve tissue and does not occur when the skin nerves have degenerated. If the stroke is injurious, histamine is released from damaged cells, water moves from the capillaries into the tissues and a swelling ensues. This is called a wheal and flare reaction or a hive.

The Function of the Skin

The skin has many functions, these include:

Secretion – The skin secretes sebum from the underlying sebaceous glands. This natural oil helps to keep the skin supple.

Heat Regulation – The body temperature is regulated through the skin. Sweating helps to cool the skin, while shivering helps to warm the body up.

Absorption – Substances can be absorbed through the skin which can be transported into the blood stream.

Protection – The skin acts as a protective barrier against germs and bacteria. The skin also contains Melanocytes which produce Melanin, and this helps protect the skin against UV radiation.

Excretion The skin contains sweat glands which help to excrete excess waste and toxins out of the body.

Sensation – The skin contains thousands of nerve endings which act as sensors for pain. Heat or cold.

Vitamins – The skin helps make Vitamin D which Is created by a chemical reaction to Sunlight