## Structure
<ul>
 <li>Superficial to deep:&nbsp;</li>
 <ul>
 <li>Skin (thinnest in the body)</li>
 <li>Subcutaneous tissue</li>
 <li>Orbicularis oculi fibres</li>
 <li>Orbital septum/tarsal plates</li>
 <li>Levator (in upper lid)</li>
 <li>Conjunctiva</li>
 </ul>
</ul>
<HotTopic>Grey line sits between lashes and openings of the tarsal (meibomian) glands</HotTopic>
<ul>
 <li>
 Defines the anterior lamellae (skin/lashes, subcut tissue, orbicularis) from posterior lamellae
 (tarsal plate and conj)
 </li>
</ul>
<ul>
 <li>Posterior to tarsal glands the conjunctiva meets the keratinised epithelium of the skin.</li>
</ul>
<ul>
 <li>25-35 Meibomian (tarsal) holocrine glands sit within the tarsal plates&nbsp;</li>
 <ul>
 <li>Secrete the lipid layer of the tear film</li>
 <li>Drain into a central ductule opening at the mucocutaneous border</li>
 <li>Secretion increases with age</li>
 <li>Mixture of lipids with a melting point of 35 degrees</li>
 <li>There are more glands in the upper than lower tarsus</li>
 </ul>
</ul>
<ul>
 <li>Sebaceous glands of Zeis open into the ciliary follicles (holocrine glands):</li>
 <ul>
 <li>
 There are also more sebaceous glands in the upper than lower lid (two glands per cilium)
 </li>
 <li>Secrete via plasma membrane rupture which destroys the cells at time of secretion</li>
 </ul>
</ul>
<ul>
 <li>Modified sweat glands of Moll (apocrine glands):</li>
 <ul>
 <li>
 There are more in the lower than the upper lids
 </li>
 <li>They secrete via pinched off membrane vesicles containing secretion</li>
 </ul>
 <li>
 Note: glands of Zeis and Moll are located in the anterior lamellae of the lids, associated with
 the lash follicles
 </li>
</ul>
<ul>
 <li>Caruncle medially with adjacent plica semilunaris</li>
</ul>

## Arterial supply

<ul>
 <li>Superior and inferior medial palpebral arteries are branches of ophthalmic artery</li>
 <li>
 Superior and inferior lateral palpebral arteries are branches of lacrimal artery (branch of
 ophthalmic)
 </li>
 <li>
 The two branches of each palpebral artery form marginal and peripheral arterial arches which
 anastomose across the lids
 </li>
 <li>
 Further anastomoses between the circulations of the internal and external carotid occur in the
 lids: branches of the superficial temporal, transverse facial and infraorbital arteries
 </li>
</ul>
<HotTopic>
The pre-tarsal portion of the eyelids is supplied by the superficial temporal and facial artery
 branches. The post-tarsal portion is supplied by branches of the ophthalmic as above
</HotTopic>
<ul>
 <li>
 The arches run anterior to the tarsal plate and Muller&rsquo;s muscle but behind orbicularis
 </li>
 <li>The marginal arch runs 3mm from the lid margin</li>
 <li>The peripheral arch is often absent inferiorly</li>
</ul>

## Venous drainage
<ul>
 <li>Ophthalmic and angular veins medially</li>
 <li>Superficial temporal vein laterally</li>
</ul>

## Lymphatic drainage
<ul>
 <li>Lateral two-thirds: superficial parotid nodes and preauricular nodes</li>
 <li>Medial third: submandibular nodes</li>
</ul>

## Nerve supply
<ul>
 <li>
 Upper lids&rsquo; skin supplied by branches of the ophthalmic nerve (V1) : supratrochlear,
 infratrochlear, supraorbital and lacrimal
 </li>
 <li>Medial lower lids&rsquo; skin supplied by infratrochlear branch of ophthalmic</li>
 <li>
 Lateral lower lids&rsquo; skin supplied by infraorbital nerve which is the terminal branch of
 the maxillary nerve (V2)
 </li>
</ul>

## Orbital septum
<ul>
 <li>Thickened continuation of the periosteum (connective tissue) both above and below</li>
 <li>Defines the anterior limit of the orbit</li>
 <li>Attached to orbital margins: arcus marginalis</li>
 <li>
 Posterior to medial palpebral ligament which attaches tarsi to lacrimal crest
 and frontal process of maxilla
 </li>
 <li>
 Anterior to lateral palpebral ligament which attaches tarsi to marginal
 tubercle of zygoma
 </li>
 <li>
 Attached to levator aponeurosis just above where the levator inserts into orbicularis (ie just
 above the skin crease) and just above the superior border of the tarsus
 </li>
 <li>The lower lid septum actually inserts directly onto the inferior tarsal border</li>
</ul>
<ClinicalCorrelate>
 The orbital septum prevents the spread of pre-septal cellulitis into the orbit
</ClinicalCorrelate>

## Tarsal plates

<ul>
 <li>Upper tarsus: 11mm</li>
 <li>Lower tarsus: 4mm</li>
 <li>1mm thick</li>
 <li>About 29mm wide</li>
 <li>Embedded with meibomian glands</li>
 <li>The bulbar conjunctiva adheres to the tarsus</li>
</ul>

## Levator
<ul>
 <li>Derived from the common tendinous ring at superolateral optic foramen</li>
 <ul>
 <li>Attached to inferior surface of lesser wing of sphenoid</li>
 </ul>
 <li>Passes above superior rectus</li>
 <li>
 Fibres develop a fan-shaped aponeurosis: wider than the original muscle at the level of superior
 transverse ligament of Whitnall
 </li>
 <li>Aponeurosis descends behind orbital septum and inserts into tarsal plate&nbsp;</li>
</ul>
<HotTopic>
 Some fibres continue on and attach to skin, creating primary lid crease
</HotTopic>
<ul>
 <li>The aponeurosis divides the lacrimal gland into orbital and palpebral portions</li>
 <li>Lateral horn inserts into marginal tubercle of zygoma</li>
 <li>Medial horn blends with the septum and medial palpebral ligament.</li>
 <li>Note: the horns act as &lsquo;checks&rsquo; on the action of levator with the eyelid</li>
 <li>Function: raises lid by 15mm</li>
 <li>
 Innervation: superior branch of oculomotor nerve which penetrates through superior rectus to
 reach the levator and then penetrates levator at the posterior ⅓-anterior ⅔
 </li>
 <li>
 Smooth muscle of Muller (superior tarsal muscle) arises from inferior surface of levator and
 inserts into tarsal plate
 </li>
</ul>

## Superior transverse ligament of Whitnall
<ul>
 <li>
 Supports upper lid and acts as a check for the levator: prevents posterior displacement and
 provides a fulcrum so the direction of levator can turn from horizontal to vertical
 </li>
 <li>
 Comprises a bundle of fascia beneath the superior orbital rim extending from the lacrimal gland
 to the trochlea
 </li>
 <ul>
 <li>Medial insertion at the trochlea</li>
 <li>Lateral insertion at the frontozygomatic suture</li>
 </ul>
 <li>Weakening with age can lead to ptosis</li>
</ul>

## Orbicularis oculi

<ul>
 <li>Flat elliptical striated muscle</li>
 <li>Orbital, palpebral (or &lsquo;pretarsal&rsquo;) and lacrimal portions</li>
 <ul>
 <li>Orbital: arises from medial palpebral ligament</li>
 <ul>
 <li>Forms circumferential fibres around orbital margin</li>
 <li>Some fibres insert into the skin and soft tissue of eyebrow</li>
 <li>Under voluntary control</li>
 </ul>
 <li>Palpebral portion is &lsquo;button-holed&rsquo; by palpebral fissure</li>
 <ul>
 <li>Also arises from medial palpebral ligament</li>
 <li>Fibres intertwine to form the lateral palpebral raphe</li>
 <li>Sits anterior to orbital septum and tarsal plate</li>
 <li>Provides reflex (involuntary) blinking and some voluntary function</li>
 </ul>
 <li>Lacrimal portion attached to the posterior lacrimal crest</li>
 <ul>
 <li>Passes deep to the medial palpebral ligament&nbsp;</li>
 <li>Attaches to posterior lacrimal crest behind the lacrimal sac</li>
 <li>Pull the lids and papillae medially during blinking</li>
 </ul>
 </ul>
</ul>
<ul>
 <li>Medial fibres surround the canaliculi</li>
 <li>Nerve supply: temporal and zygomatic branches of the facial nerve</li>
</ul>
<ClinicalCorrelate>
 Paralysis of orbicularis leads to ectropion and upper lid retraction
</ClinicalCorrelate>
<ul>
 <li>Contains Riolan&rsquo;s muscle and Horner&rsquo;s muscle</li>
 <li>Riolan&rsquo;s muscle</li>
 <ul>
 <li>Striated muscle fibres next to anterior border of the tarsal plate</li>
 <li>Represents the grey line</li>
 <li>Extends the length of the eyelid and is the most posteriorly placed orbicularis portion</li>
 <li>
 Together with pretarsal orbicularis, surrounds the canaliculus to shorten it during blinking
 and promote tear drainage
 </li>
 </ul>
</ul>

## Preaponeurotic fat

<ul>
 <li>Situated behind the orbital septum and in front of the muscular portion of the levator</li>
 <li>Divided into medial and lateral pad (larger) by the trochlea</li>
 <li>
 The medial pad is more fibrous giving it a whitish colour while the lateral pad is yellowish
 </li>
</ul>

## Eyebrows

<ul>
 <li>5 groups of muscles move the eyebrows</li>
 <ul>
 <li>
 (Occipito)Frontalis elevates the eyebrows: supplied by the temporal branches of the facial
 nerve
 </li>
 <ul>
 <li>Elevates the eyebrows and moves the scalp forward</li>
 <li>Produces furrows in forehead</li>
 <li>Extends from eyebrows to nuchal lines</li>
 </ul>
 <li>
 The others all depress the eyebrows
 </li>
 <ul>
 <li>Orbicularis oculi</li>
 <li>Procerus</li>
 <li>Depressor supericilii</li>
 <li>Corrugator supercilii: produces vertical furrows in forehead</li>
 </ul>
 </ul>
 <li>Procerus and corrugator also move the eyebrows medially</li>
 <li>Frontalis: deficient laterally (only supports the medial 2/3rds hence lateral ptosis)</li>
 <li>
 All are supplied by the facial nerve
 </li>
</ul>

## Eyelashes

<ul>
 <li>Twice as many and longer on the upper lid</li>
 <ul>
 <li>150 in the upper compared to 75 in lower lid</li>
 </ul>
 <li>Glands of Zeis and Moll open into the hair follicles</li>
 <li>No erector pili muscles</li>
 <li>Replaced every 100-150 days (3-5 months)</li>
</ul>

Structure Superficial to deep: Skin (thinnest in the body) Subcutaneous tissue Orbicularis oculi fibres Orbital septum/tarsal plates Levator (in upper…

Orbit and ocular adnexae

Eyelids

Intro

FRCOphth Part 1 Study Notes

Orbit

Extraocular Muscles

Orbital Blood Vessels

Paranasal Sinuses

Lacrimal Glands

Tear Film

Blinking

Anterior segment - ocular surface

Conjunctiva

Conjunctivitis

Sclera

Cornea

Corneal Structure And Development

Corneal Physiology

AC to Lens

Angle

Ciliary Body

Aqueous Humour Dynamics

Iris

Pupil

Lens

Posterior segment

Choroid

Vitreous

Retinal Macrostructure

Neurosensory Retina

Retinal Pigment Epithelium

Neuroanatomy

Venous Sinuses

Cerebral Ventricles

Cerebral Blood Supply

Supranuclear Gaze Pathways

Head And Neck Autonomic Nervous Supply

Head And Neck Glands

Osteology

Nerves

Muscles And Pharyngeal Arches

Extraocular Nerves

Sensory Nerves

Physiology

Physics Of Blood Flow

Neuronal Control Of Blood Vessels

Oxygen-Haemoglobin Dissociation Curve

Cytochrome p450

Pituitary Gland

Thyroid Hormone Production

Insulin

Glucagon

Parathyroid Hormone

Corticosteroids

Catecholamines

Cardiac Cycle

Renal Physiology

Fluid Balance

Acid-Base Balance

Muscle Physiology

Sensory Fibres

Cutaneous Receptors

Endocytosis

Glycosaminoglycans

Condensed Ocular Biochemistry

Eye Movements

Accomodation

Vision

Visual Cycle And Phototransuction

Visual Pathway

Visual Acuity

Colour Vision

Binocular Vision

Pathology

Collagen

Tissue Damage

Inflammation

Disease Entities

Wound Healing

Thrombosis / Atherosclerosis

Cell Growth

Neoplasia

Histopathology

Nystagmus

Free Radicals And Antioxidants

Immunology

Ocular Immunology

Microbiology

Viral Infections

Bacterial Infections

Fungal Infections

Protozoa

Nematodes

Antimicrobials

Genetics

Chromosomes

Mitosis

Meiosis

Genes

Polypeptide Synthesis

Histones

MicroRNA

Hardy-Weinberg Equilibrium

Mutations

Chromosome Defects

Autosomal Inheritance

X-Linked Inheritance

Mitochondrial Inheritance

Multifactorial Inheritance