Upper Eyelid Anatomy- 5 Key Points
The upper eyelid is made up of 3 compartments (lamella), each of which contain a mixture of skin, muscle, fat, tarsal plate and conjunctiva. This article explores this anatomy in more detail and is key to understanding ptosis.
1. Tri-Lamellae Structure
The upper eyelid is a tri-lamellae structure (anterior, middle and posterior)
2. Anterior Lamella
The anterior lamella is a well-vascularised external cover, which consists of skin and orbicularis oculi (orbital, preseptal and pretarsal divisions)
3. Middle Lamella
The middle lamella provides structural support. It is a relatively new term and refers to the pre-septal fat, orbital septum and post-septal fat.
4. Posterior Lamella
The posterior lamella provides mucosal lining and support through the tarsal plate, conjunctiva and upper eyelid muscle retractors.
5. Neurovascular Supply
The main blood supply to the upper eyelid is the ophthalmic artery.
The main nerve supply is the ophthalmic division of CN V (V1).
Summary of Upper Eyelid Anatomy
The upper eyelid provides dynamic protection of the globe through 3 layers, as described in this table.
| Lamellae | Structure | Notes |
|---|---|---|
| Anterior Lamella | Skin | 1mm thick |
| Orbicularis Oculi | Orbital, Pre-septal, Pre-tarsal | |
| Middle Lamella | Pre-septal fat | Retro-orbicularis oculi fat |
| Orbital Septum | Separates eyelid from orbit | |
| Post-septal fat | Medial and Central | |
| Posterior Lamella | Tarsal Plate | Structural support |
| Upper Eyelid Retractors | Levator Palpebrae Superioris and Mueller’s Muscle | |
| Conjunctiva | Palpebral and Bulbar |
Upper Eyelid Anatomy Mnemonic
Upper Eyelid anatomy is complex & best remembered by the “Rule of 1, 2, 3 4” mnemonic.
1 Eye
2 Eyelids: Upper Eyelid and Lower Eyelid
3 Compartments: Anterior, Middle, and Posterior Lamella
4 Structures in each compartment
- Anterior: Skin; Pre-septal, Pre-tarsal and Orbital orbicularis oculi
- Middle: Pre-septal fat; Orbital Septum; Medial and Central Post-Septal Fat
- Posterior: Tarsal Plate, Levator Aponeurosis; Mueller’s Muscle; Palpebral and Bulbar Conjunctiva
Anterior Lamella Anatomy
The Anterior Lamella is composed of Skin and Orbicularis Oculi muscle.
Skin
- Thinnest on the human body
- Loosely adherent to underlying orbicularis oculi muscle
- Approximately 1mm thick
- Excess skin is called Dermatochalasia and can be a cause of pseudoptosis.
Orbicularis Oculi
The orbicularis oculi muscle is divided into 3 parts, organised concentrically around the palpebral fissure. The orbicularis oculi muscle is innervated by the temporal and zygomatic branches of the facial nerve.
The 3 components of the orbicularis oculi muscle are described in this table:
| Components of Orbicularis Oculi Muscle | Function |
|---|---|
| Orbital Component | Outermost aspect of muscle |
| Superficial to corrugators & procerus | |
| Voluntary lid closure | |
| Pre-septal | Covers the orbital septum |
| Voluntary and involuntary movements | |
| Pre-tarsal | Covers the tarsal plate |
| Involuntary blink |
“Middle” Lamella
The “Middle Lamella” is a relatively new term and consists of the pre-septal fat, the Orbital Septum and post-septal fat.
Orbital Septum
The orbital septum is an extension of the orbital periosteum.
- It extends from the superior orbital rim as a thickening called the arcus marginalis. This is where the facial and orbital periostea meet the posterior layer of the galea to form the septum.
- It inserts direclty onto the tarsus (in some asians) or via the levator aponeurosis.
This fibrous membrane of connective tissue has a role in:
- Insertion of Levator aponeurosis (which inserts onto the tarsal plate)
- It contains the nasal and central fat pads.
- A marker that distinguishes pre-septal and orbital cellulitis.
It separates the anterior and posterior lamella of the upper eyelid. This junction is denoted by a visible grey line on the eyelid. Attenuation of the septum results in psuedoherniation of the intra-orbital fat.
Fat Compartments
It is sometimes referred to as the “middle lamella” because of the pre-septal/post-septal fat compartments adjacent to the orbital septum.
This pre-septal fat is located between the septum and orbicularis muscle. In the upper lid, it is called retroorbicularis oculi fat (ROOF) and has a role in upper lid hooding and puffiness.
Post-septal (pre-aponeurotic) fat pad lies between septum and levator aponeurosis. In the upper eyelid, there is a medial and central fat pad, which are separated by the trochlea of the superior oblique muscle. This is important in the pre-operative examination of a ptotic patient.
Posterior Lamella Anatomy
The Posterior Lamella is composed of Tarsal Plate, Conjunctiva, and Upper Eyelid Muscle Retractors (Levator Palpebrae Superioris, Meuller’s Muscle)
Upper Lid Tarsal Plate
The Upper Lid Tarsal Plate is approximately 25mm-30mm horizontal, 1 mm thick, and 10mm vertical. The tarsoligamentous complex is the connective tissue structural support of the eyelids. It also contains meibomian glands, which secretes lipid component of the tear film just posterior to the grey line
The tarsal plate inserts into the orbital rim by the medial and lateral retinacular supporting structures. It is the insertion point for the following:
- Levator aponeurosis
- Levator palpabrae superioris (innervated by Oculomotor muscle)
- Muller Muscle (innervated by sympathetic system)
Bulbar Conjunctiva
Tissue that lines the inside of the eyelids and covers the sclera (the white of the eye).
Levator Palpebrae Superioris
The Levator Palpebrae Superioris (LPS) acts as a fulcrum and provides 10-15mm of upper lid elevation and sustain lid elevation.
Important anatomical points on this muscle include:
- Origin: Lesser wing of sphenoid
- Insertion: Dermis and superior edge of tarsus, which creates a supratarsal crease and upper eyelid fold. This insertion is much lower in Asians.
- Innervation: CN III
Importantly, the muscle broadens to form an aponeurosis at Whitnall’s Ligament. This is a fascial condensation 14-20mm from the superior edge of tarsus; translates posterior vector of pull into superior vector.
Müller’s Muscle
This muscle is also known as the superior tarsal muscle. Important anatomical points include:
- Origin: Levator muscle
- Insertion: Superior edge of tarsus,
- Innervation: Sympathetics
- Action: 1-3mm of upper lid lift.
Neurovascular System
In comparison to the tri-lamella eyelid structure, its blood and nerve supply is much easier to understand.
The eyelid receives dual blood supply from the external and internal carotid systems, which anastomose via:
- Facial artery and Angular Artery at the medial canthus
- Superficial temporal artery at the lateral canthus
- Infra-orbital artery at the lower eyelid.
The main blood supply to the upper lid is the ophthalmic artery, which gives off peripheral and marginal arcades.
The sensory innervation of the upper eyelid. is primarily by the ophthalmic division of CN V (V1).
