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Face, Mid-face, Cheek, Eyelid and Orbit Anatomy

Understanding Facial Anatomy

  • Your face is made up of layers of tissues varying in texture and consistency.   These tissue layers overlie {the} bony skull, which provides {the} support for and structure of your face. From a cosmetic surgeon’s standpoint, your face is made up of {the} following components: skin, fat, superficial musculoaponeurotic system (SMAS), platysma muscle, Erb’s point (containing important nerves), deep cervical fascia and {the} retaining ligaments of {the} face. Mastering {the} art of tweaking these components in {the} correct proportion and in an aesthetically pleasing manor is {the} surgeon’s delight and goal, {the} reward being {the} facial iimprovementthat you desire.
  • The thickness of skin overlying your face is variable - your eyelids have {the} thinnest skin while your cheeks and forehead are covered by a thicker skin. Facial skin is repeatedly exposed to {the} sun and elements.  This skin is also affected by aging, resulting in loss of elasticity and {the} development of rhytids or wrinkles. The skin consists of two main layers - {the} inner layer called dermis and {the} outer layer called epidermis. Our epidermis is what everyone sees!

anatomy of face facelift surgery muscles

  •  Fat is one of {the} most important components of your face and lies just beneath your skin, i.e. subcutaneous fat. It consists of lobules partitioned by fibrous septa which connect {the} inner layer of {the} skin, {the} dermis, to {the} superficial fascia just beneath {the} fat. The distribution of fat in {the} face is variable, with a major portion deposited right beneath your cheek as {the} malar fat pad. It is also found below {the} eyes, lateral to your nose, and in front of your ears. Fat accentuates your cheek bones nicely. The malar fat pad is propped up by connections to {the} orbitomalar ligament, {the} superficial musculoaponeurotic system (SMAS), underlying soft tissue, and bone. With age, {the} malar fat pad shrinks, causing {the} cheeks to droop towards {the} crease between your nose and lips. This drop of cheek tissue results in a deeper fold and shadow-- a definite sign of aging.
  • The SMAS or superficial musculoaponeurotic system covers and connects {the} muscles of facial expression to {the} deeper layers of your face. It lies beneath {the} fat layer of your skin and provides definition to your facial expressions.  The SMAS is a thin layer of connective tissue that lies attached closely with {the} platysma muscle, frontalis muscle, galea and superficial temporal fascia. It is also closely attached to {the} superficial muscles of facial expression (including {the} orbicularis muscle), pre-orbicularis fat and {the} malar fat pad. The SMAS is attached to bone at {the} infraorbital rim, zygoma, and {the} mandible.
  • The Platysma is a thin, flat muscle that begins in {the} chest just in front of your collar bone, {the} clavicle, moving up towards {the} face and covering {the} front and sides of {the} neck.  It eventually attaches to your jaw bone and skin, then merges with several muscles and continues as {the} SMAS over {the} parotid (salivary) gland and cheek. Both sides of {the} Platysma merge at {the} midline just below your jaw line. As one ages, {the} platysma muscle becomes loosely attached to {the} underlying structures resulting in vertical banding and bowing under {the} chin.
  • The Deep Cervical Fascia is a connective tissue in {the} neck that covers and protects {the} muscles, nerves, blood vessels and glands of {the} face. Surgery deep to {the} deep cervical fascia can result in injury to {the} facial nerve, which is {the} primary nerve supply to {the} face.  Damage to any of its five branches could cause weakness of {the} muscles supplied by that particular branch.   Utmost care must be taken to avoid injury to {the} facial nerve or its branches.
  • Erb’s point lies vertically below {the} ear canal just behind {the} sternocleidomastoid muscle and represents {the} point of emergence of several nerves that provide sensation to {the} neck and lower face. It lies just over {the} sternocleidomastoid muscle. Its largest branch, {the} greater auricular nerve emerges 6.5 cm below {the} ear canal and provides sensations to {the} lower portion of {the} ear and area just behind {the} ear. Hence, it is important to meticulously dissect this area to avoid damaging any of these nerves.
  •  Retaining ligaments or tendons provide support to {the} soft tissues of {the} face and also provide points for movement of muscles of facial expression. The retaining ligaments important during rhytidectomy surgery are:
  • Osteocutaneous ligaments: connecting from bone to {the} inner layer of {the} skin ({the} dermis). Zygomatic and orbito-malar ligaments suspend {the} soft tissue of {the} malar region. The submental crease is formed by {the} mandibular osteocutaneous ligament.
  • Fascial-cutaneous ligaments bind {the} superficial and deep fascial layers of {the} face.

 

 

 

Underneath {the} skin, along with {the} subcutaneous tissue is a thin layer of fat. However, {the} amount of fat is negligible when compared to other parts of {the} body. Typically, subcutaneous tissue is absent at points where {the} skin is attached directly to underlying ligaments such as {the} medial and lateral palpable ligaments. The skin and subcutaneous tissue can be subject to certain clinical conditions such as dermatochalasis and blepharochalasis.

Submuscular areolar tissue

  • This is a loose connective tissue that lies beneath {the} orbicularis oculi muscle. It can form an anatomical plane that divide {the} eyelid into a front (anterior) and back (posterior) portion. The fibres of {the} levator aponeurosis then passed through this plane in {the} upper eyelid. A small portion of these fibres contribute towards {the} development of {the} upper eyelid crease. Similarly, in {the} lower eyelid, {the} fibres of {the} orbitomalar ligament passed through this plane.
  • If this anatomical plane were to be tracked towards {the} eyebrow area, {the} retro-orbicularis oculi fat will be traversed. If {the} plane were to be tracked towards {the} cheek, {the} sub-orbicularis oculi fat would be traversed.

 

Orbicularis retaining ligament

  • Also called {the} orbital retaining septum or orbitomalar ligament, this ligament attaches {the} orbicularis oculi muscle to {the} lower rim of {the} orbit. It is weak in its central aspect, and a lot stronger in {the} lower-outer aspect. When traced laterally, it is contiguous with tissue that is formed by fusion of {the} outer part of {the} orbicularis oculi and {the} deeper periosteum and temporalis fascia. This fusion is called {the} orbital thickening. This orbital thickening covers {the} frontal process of {the} zygomatic bone.
  • As one gets older, {the} orbicularis retaining ligament tends to get thinned out and stretched, with these changes more prominent in {the} central aspect. When excised along with {the} orbital thickening, it results in full release of {the} superficial fascia that lines {the} orbital rim.

Upper lid retractors

  • The upper lid retractors are a group of muscles whose main function is {the} keep {the} upper eyelid elevated. The muscle that forms a part of this is called {the} levator palpebrae superioris (LPS). This muscle originates from {the} bottom aspect of {the} lesser wing of {the} sphenoid bone located within {the} skull. It consists of 2 heads - {the} levator muscle and {the} superior rectus muscle. They are joined together by fibrous tissue. From its origin, {the} LPS traverses horizontally forward for about 40mm, ending in an aponeurosis that is around 10mm posterior to {the} orbital septum. It then takes a more vertical course toward {the} Whitnall ligament (superior transverse ligament).
  • The Whitnall ligament is similar to {the} previously described orbital fascia and lies in close proximity to {the} aponeurotic and muscular junction of {the} LPS. It extends around {the} upper margin of {the} orbit in a plane that lies between {the} lacrimal gland fascia and {the} trochlea. The LPS varies in thickness, and is relatively thin in areas between {the} upper orbital rim and {the} Whitnall ligament.
  • When traced inwards and outwards, {the} LPS aponeurosis forms ‘horns’ called medial and lateral horns. The lateral horn runs through {the} lacrimal gland, dividing it into 2 lobes - {the} palpebral lobe and {the} orbital lobe. Having done this, it goes on to attach to {the} lateral retinaculum located at {the} lateral orbital tubercle. On {the} other hand, {the} medial horn has a more direct course and is fixed to {the} posterior lacrimal crest.
  • The aponeurosis eventually reaches {the} border of {the} superior tarsal plate having fused initially with {the} orbital septum. At {the} bottom end of this fusion, a small part of {the} aponeurosis attaches to {the} lower aspect of {the} anterior part of {the} tarsal plate. One part of this fusion extends forwards to insert into {the} pretarsal orbicularis oculi muscle and skin, resulting in {the} formation of {the} skin crease in {the} upper eyelid. 

Fat Pads

  • There are a number of different fat pads that are present within and around {the} eyelid. One layer of fat called {the} pre-aponeurotic fat is found right behind {the} orbital septum and in front of {the} levator aponeurosis. Also within {the} upper eyelid are two more areas that contain fat pads that are centrally and medially (towards {the} nose) located. The medial fat pad is pale yellow in colour and lies in front of {the} levator aponeurosis.
  • On {the} other hand, {the} central pad of fat is broader and yellow in colour. As it travels outwards, it wraps around {the} inner aspect of {the} lacrimal gland. The lacrimal gland can be clearly seen and differentiated from this fat by its pink colour and lobulated structure. The lacrimal gland is positioned just posterior to {the} orbital margin but could prolapse slightly making it more prominent when {the} eye is examined.
  • While {the} above described {the} fat pads within {the} upper eyelid, {the} lower eyelid fat pads are slightly different in structure. The inferior oblique muscle separates {the} central fat pad from {the} dinner medial fat pad. There is a small amount of fat that lies in front of {the} inferior oblique muscle as well. The inferior oblique muscle originates from a small indentation in {the} lower border of {the} orbital floor, moving behind {the} orbital margin and at {the} upper aspect of {the} nasal lacrimal canal. It passes underneath {the} inferior rectus muscle and through {the} Tenon capsule, ultimately inserting at {the} point close to {the} macula of {the} eye. This rather winding course of {the} inferior oblique muscle makes it vulnerable to injury during this section of {the} fat pads around {the} eyelid and eye.

Blood supply

  • The eyelids are supplied by branches of {the} internal and external carotid arteries. The ophthalmic artery branches off {the} internal carotid artery and supplies different parts of {the} eyelid. At {the} inner part of {the} upper eyelid, {the} ophthalmic artery splits into two and traverses outwards {the} supply both {the} upper and {the} lower eyelid. The branch that supplies {the} lower eyelid is in fact a branch that arises from {the} superior marginal vessel (that supplies {the} upper eyelid). The superior and inferior marginal vessels that arise from {the} ophthalmic artery together form {the} marginal arcade.
  • The marginal arcade arteries are located at {the} front of {the} tarsus, 4 mm from {the} upper eyelid and 2 mm from {the} lower eyelid margin each. The superior marginal arcade gives rise to a peripheral arcade that runs in front of {the} Muller muscle, giving it a superficial plane and making it prone to injury during eyelid surgery. The peripheral arcade in {the} lower eyelid is often rudimentary.
  • Another branch of {the} internal carotid artery is {the} lacrimal artery that passes through {the} orbital septum along each eyelid and ultimately joins {the} marginal arcade.
  • While {the} above described {the} branches of {the} internal carotid artery, {the} external carotid artery supplies {the} eyelids as branches of {the} facial artery, infraorbital artery and {the} superficial temporal artery. Each of these pride branches that anastomosis with other arteries on {the} face. For example, {the} branch of {the} superficial temporal artery that supplies {the} eyelids joins with {the} zygomatic branch and transverse facial branch.