Lids & Conjunctiva Flashcards
What are the functions of the eyelid?
- Protection (from light entering the eye, direct trauma, air particles)
- Lubrication (distributes tear film, provides comfort, removes debris)
- Globe Position (maintains position in orbit with conjunctiva)
What are the layers of the eyelid?
- Skin
- Subcutaneous tissue (very little fat)
- Orbicularis oculi
- Orbital septum and tarsus
- Levator palpebrae superioris (upper lid only)
- Smooth muscle
- Conjunctiva
SSOOLSC
How many layers of the eyelid are there?
Seven
What is the grey line of the eyelids?
The gap between lamellae
What is the lamallae in contact with?
The palpebral conjunctiva
What conjunctiva is in contact with the eye?
The orbital conjunctiva is between the tarsal plate and the fornix
What is the lamellae?
A thin layer of the lid that’s separated into anterior and posterior by the grey line
What’s included in the anterior lamella?
Skin and Orbicularis
What’s included in the posterior lamella?
Tarsus and Conjunctiva
What’s the orbicularis oculi?
Concentric bands of striated muscle
What cranial nerve innervates the orbicularis oculi?
The facial nerve through the Temporal and Zygomatic branch
What is the orbicularis oculi responsible for?
Involuntary blinking, voluntary closing and tear drainage
What is the orbicularis oculi divided into?
Orbital, Palpebral and Lacrimal portions
What is the palpebral portion of the orbicularis oculi divided into?
Pre-septal and Pre-tarsal
What’s strongly attached to the orbicularis oculi?
Medial and lateral canthal tendons
What are the different portions of the orbicularis oculi responsible for?
Orbital - acts like purse string to strongly close the eye like in bright light
Palpebral - voluntary and involuntary closure of lids such as blinking and sleep
Lacrimal - draw lids and lacrimal papillae medially, dilate lacrimal sac during blinking
What is the orbital portion of the orbicularis oculi responsible for?
Orbital - acts like purse string to strongly close the eye like in bright light
What is the palpebral portion of the orbicularis oculi responsible for?
Palpebral - voluntary and involuntary closure of lids such as blinking and sleep
What is the lacrimal portion of the orbicularis oculi responsible for?
Lacrimal - draw lids and lacrimal papillae medially, dilate lacrimal sac during blinking
What’s the ciliary muscle in the orbicularis oculi also known as?
Muscle of Riolan
What’s the muscle of Riolan also known as?
Ciliary muscle (not the intra-ocular ciliary muscle)
What is the ciliary muscle / muscle of Riolan of the orbicularis oculi?
It’s at the lid margin consisting of a small group of very fine muscle fibres
What is the function of the ciliary muscle or muscle of Riolan?
To allow apposition and touching of the eyelids when we close our eye
What’s the orbital septum and extension of?
The orbital septum is an extension of the periosteum from orbital roof and orbital floor
What’s the function of the orbital septum?
To separate the lids from orbit, it’s clinically significant (pre-septal vs. orbital cellulitis). Very thin but has a huge protective function
What does the orbital septum separate?
The orbital septum separates the anterior and posterior lamellae
Where does the LPS originate?
Lesser wing of the Sphenoid
Where does the LPS insert?
Into the upper lid skin via aponeurosis
What’s the role of the LPS?
Elevation and retraction of the upper lid
What’s the anatomical site of where neurosis begins to form?
Whitnall ligament
What’s an aponeurosis?
An aponeurosis is a thin sheath of connective tissue that helps connect your muscles to your bones. Aponeuroses are similar to tendons. They support your muscles and give your body strength and stability. Tough tissue.
What is Whitnall’s ligament?
Whitnall’s ligament was first described in 1910 by Dr. Samuel Ernest Whitnall as a superior transverse ligament above the musculotendinous junction of the levator palpebrae superioris.[1][2] It is formed by a collection of muscle sheaths from the levator palpebrae superioris muscle that assemble into a ligament in the area where the levator palpebrae muscle becomes an aponeurosis.
It attaches to the superior rectus muscle tendon sheath, the medial side of the trochlea, and to the lateral orbital margin
What is Whitnalls ligament also known as?
Superior Transverse Ligament
What does the Superior Transverse Ligament/Whitnalls ligament form?
Aponeurosis
What division of CN III is the LPS part of?
Superior Division
What is blood to the LPS supplied by?
Ophthalmic and supraorbital arteries supply the LPS
What’s the superior tarsal muscle also called?
Muller’s Muscle
What is Muller’s Muscle also known as?
The Superior Tarsal Muscle
Where does Muller’s Muscle originate?
From the LPS at the level of Whitnall’s ligament
Where does the Superior Tarsal Muscle insert?
Into the tarsal plate
What’s the role of Muller’s Muscle?
Elevates the upper lid
What is Muller’s Muscle muscle type?
Smooth muscle
Is Muller’s Muscle under sympathetic and parasympathetic innervation?
Sympathetic
What is the inferior tarsal muscle analogous with?
Muller Muscle but it’s in lower lid
What’s the major bulk of posterior lamellae?
Tarsal plates. Thick but thinner and rounded towards the end of the eyelid
What glands do the tarsal plates contain?
Meibomian glands that open at lid margin for oil secretion
What are the mm of the tarsal plates?
Upper = 10mm
Lower = 5mm (has fewer glands)
How do the tarsal plates attach?
Skin moves freely over anterior surface, conjunctiva is densely adherent to posterior surface
Form the medial and lateral canthal ligaments which attach to maxilla and zygoma, respectively
How big is the lid margin?
30mm x 2mm
What is the lid margin separated into?
2 sections by lacrimal puncta:
Lateral - 5/6th square edged
Medial - 1/6th round edged without lashes. Water collects medially in the corner at the lacrimal lake.
How is the lid margin organised from anterior to posterior?
Anterior to posterior:
Skin
Lashes (out of the anterior lamellae)
Grey line
Meibomian gland orifices
Mucocutaneous junction (anchoring point of the palpebral conjunctiva to the eyelid)
Conjunctiva
What is epiphora?
Watery eyes (would be like a waterfall if the inferior puncta is blocked or not working).
This can irritate the skin which affects lower eyelids and cheekbones but also comprises vision.
What is the role of the lashes?
Protection from debris and prevent film evaporation as a secondary function.
The tertiary function is glands that open to the eyelash and keep it supple being the Glands of Zeis and the Glands of Moll
What are Meibomian glands?
Type of sebaceous gland in tarsal gland
How many meibomian glands are there?
30 in the upper lid, fewer in the lower lid
What do the meibomian glands secrete?
Meibum
What is the function of meibomian glands?
To prevent evaporation of aqueous tear film
What do blocked meibomian glands cause?
Chalazions & Hordealum
Chalazions = blocked meibomian glands that are not infective (so not tender or painful but can affect the skin on the eyelids).
If they’re infected then they become a stye (hordealum)
How do you treat a stye or chalazion?
Stye = antibiotics
Need to tell them to have eyelid hygiene (how to clean them) and do a warm compress to the eye to relax the openings of the meibomian glands to allow evacuation of the content in them
What are the Glands of Moll?
Modified apocrine sweat glands that help keep lashes supple
What are the Glands of Zeis?
Sebaceous glands to lash follicles that also maintain quality of lashes (they open into hair follicles)
What’s the corneal reflex?
When something touches the eye, we blink
What is the receptor, afferent pathway, first synapse, second synapse, efferent pathway and effector muscle of the Corneal Reflex?
Receptor - Sensory ending in corneal epithelium
Afferent Pathway - Long ciliary nerves, nasociliary nerve, ophthalmic nerve
First synapse - Spinal nucleus of trigeminal
Second synapse - Facial nucleus
Efferent pathway - Temporal and zygomatic branches of facial nerve
Effector muscle - Orbicularis oculi
What is the receptor, afferent pathway, first synapse, second synapse, efferent pathway and effector muscle of the ‘Blinking to light’ or fast-approaching object’?
Receptor - Retina
Afferent Pathway - Optic nerve
First synapse - Superior Colliculus
Second synapse - Facial nucleus
Efferent pathway - Temporal and zygomatic branches of facial nerve
Effector muscle - Orbicularis oculi
What is the receptor, afferent pathway, first synapse, second synapse, efferent pathway and effector muscle of the ‘Blinking to noise’?
Receptor - Cochlea
Afferent Pathway - Vestibulocochlear Nerve
First synapse - Inferior Colliculus
Second synapse - Facial nucleus
Efferent pathway - Temporal and zygomatic branches of facial nerve
Effector muscle - Orbicularis oculi
What causes blinking?
Autonomic control, variable frequency and speed, no clear stimulus
What is Bells Palsy?
Facial nerve palsy with movement issues of the face. This can cause the cornea to dry out and perforate. If they have lagophthalmos (inability to close the eye) then they can lose vision
What is Lagophthalmos?
An inability to close the eye
How does Bells Palsy occur?
Facial nerve starts at the Pons, contralateral. Fibres cross into facial nerve nucleus which innervate facial muscles. However, uniquely, the facial nerve is ipsilateral and contralateral. A lower motor neurone lesion will affect the forehead but an upper motor neuron issue will not affect the forehead because the forehead has supply from both the contralateral and ipsilateral side. Part that controls forehead has info from both parts of the lower cortex (lower motor neurons). If someone presents with issues like this, first thing to do is to ask them to raise their forehead.
What is Ectropion?
It’s an evolution outwards of the lower eyelid. Tear film is exposed to need surgery to correct for the tear film. It’s paralytic, cicatricial, mechanical and congenital causing tear film insufficiency, dryness and pain.
What is Entropion?
Involution of the lower eyelid. Involution means age related. It’s spastic, cicatrical and congenital. It causes foreign body sensation, irritation, redness and may damage the cornea. Causes damage to the cornea every time you blink and can cause blindness. Look more up about this.
Cicatricial = can cause sparring due to mechanical rub and the eyelashes can rub against and introduce foreign bodies into the eye
What’s Cicatricial?
Cicatricial = can cause sparring due to mechanical rub and the eyelashes can rub against and introduce foreign bodies into the eye
What is the arterial blood supply pre and post-tarsal?
Pre-tarsal = superficial temporal and facial arteries (branches of external carotid artery)
Post-tarsal = Branches of ophthalmic arteries (branch of the internal carotid artery)
What is the venous supply to the medial and lateral part of the eyelids?
Medial = Ophthalmic and angular veins
Lateral = Superficial temporal veins
What are the lymphatics of the eyelid?
Follow venous drainage
Medial aspect = submandibular nodes
Lateral aspect = preauricular nodes
Where does sensory innervation to the upper lid come from?
CN V - Ophthalmic
Where does sensory innervation to the medial lower lid come from?
CN V - Ophthalmic
Where does sensory innervation to the lateral lower lid come from?
CN V - Maxillary
Where does sensory innervation from the lower lid come from?
Medial = Ophthalmic Nerve of CN V
Lateral = Maxillary Nerve of CN V
What is the conjunctiva?
A thin, translucent membrane that attaches globe to lids.
Epithelium is continuous from the mucocutaneous junction all the way to the corneal limbus
What are the functions of the conjunctiva?
Lubrication - contributes mucous part of the tear film
Reduces Friction - allows free movement of the lids
Immune Defense - contributes to protection of the eye
What is the conjunctival anatomy?
Palpebral Conjunctiva -
Adherent to tarsal plate
Forniceal Conjunctiva -
Contains some lacrimal ducts
Bulbar Conjunctiva -
Overlies anterior globe and EOMs
Caruncula Lacrimalis -
Modified skin with volumes of accessory lacrimal and sebaceous glands
Plica Semilunaris -
Fold of conjunctiva rich in Goblet and Immune cells that may facilitate lateral movement
Where is the conjunctiva stratified squamous and stratified columnar?
Epithelium varies by location and contains non-keratinized stratified squamous on palpebral part and is stratified columnar on the bulbar part
How many cells are in the conjuctiva and what cells are in the conjuctiva?
3;
Goblet Cells
Immune Cells
Melanocytes
What are the features of goblet cells?
Unicellular
Most in fornices and plica semilunaris
Produce majority of conjunctival mucins
What are the features of immune cells?
Langerhans cells help prime immune response (antigen-presenting)
Lymphocytes
What are the features of melanocytes?
Vary depending on race, contribute to pigmentation like light scattering in the eye. They can cause melanoma’s = skin cancer on and in the eye
How is the conjunctiva supplied with blood?
Rich vascular network within stroma, similar to lids
Additionally some supply from anterior ciliary arteries
How is the conjunctiva sensory innervated?
Palpebral part = mostly from CN V1
Inferomedial fornix and palpebral part = CN V2
Bulbar = long ciliary nerves
What are the 2 types of glands in the conjunctiva?
Accessory lacrimal glands and mucus-secreting glands
What are the names and locations of the accessory lacrimal glands of the conjunctiva?
Glands of Krause - in the superior fornix
Glands of Wolfring - in the superior tarsus
What are the names and locations of the mucus-secreting glands of the conjunctiva?
Glands of Henle - scattered throughout the conjunctiva
What divides the Lacrimal gland into palpebral and orbital?
Aponeurosis of the LPS
What type of gland is the lacrimal gland?
Exocrine lobulated gland
What artery supplies the lacrimal gland? Which vein drains it?
Lacrimal Artery & Superior Ophthalmic Vein
Does the Lacrimal gland receive autonomic or sympathetic fibres?
Both
Which nerve supplies sensation to the face?
Trigeminal Nerve
Which nerve supplies movement to the face?
Facial Nerve
What is the pterygopalatine ganglion?
Landmark of the lacrimal gland, becomes efferent fibres at the pterygopalatine ganglion of the parasympathetic pathway to the lacrimal gland. The nerves move together and damage to these nerves = dry eyes
How do parasympathetic fibres reach the pterygopalatine ganglion via?
Lacrimal Nucleus –> Facial Nerve –> Greater petrosal nerve
What is the parasympathetic supply to the lacrimal gland?
From facial nerve in the lacrimal nucleus/superior salivatory nucleus. Pre-ganglionic fibres are carried by the greater petrosal nerve and then the nerve of pterygoid canal to reach the pterygopalatine ganglion
What is the “secretomotor” of the parasym supply of the lacrimal nerve?
Forms the efferent pathway of the lacrimal reflex (parasym supply is of “greater” importance than sympathetic = “Greater Petrosal Nerve”)
How do post-ganglionic fibres leave the pterygopalatine ganglion?
Leave and piggyback on the maxillary nerve along the zygomatic branch and then reaches the lacrimal gland with the lacrimal nerve
Where does the sympathetic supply of the lacrimal gland originate?
Superior cervical ganglion in the sympathetic chain
In sympathetic nervous system which fibres are long and which are short?
Pre = Short
Post = Long
Where do the post-ganglionic fibres of the sympathetic supply of the lacrimal nerve travel?
Deep petrosal nerve and then follow the same course
Which gland is the responsible for baseline tear production?
Accessory Lacrimal Glands
Which glands produce lipid layer of tears?
Meibomian, Zeis and Moll
Which lubricates and aids in even distribution of tears?
Conjunctival Goblet Cells
Which glands constantly produce aqueous?
The Accessory Lacrimal Glands
What is the purpose of aqueous in tears?
Nourishes and hydrates and for immune defense
What glands produce aqueous in tears?
Lacrimal and accessory lacrimal glands
Which layers of tears are the most implicated in dry eye?
Lipid & Aqueous
What can lipid layer dysfunction be secondary to?
Blepharitis (inflamed eyelid), aging or idiopathic = dry eyes
What can cause Aqueous layer dysfunction?
Medications, allergies, trauma (chemical injuries), disease to lacrimal glands, Sjogren’s disease, rheumatoid disease of lacrimal and accessory glands (last two are both autoimmune exocrine disorders)
Where does the conjunctiva end?
At the limbus
