Ocular Anatomy: Eyebrows & Eyelids (Lecture 3)

Ocular Adnexa

• Structures surrounding the globe

• Protection & support

What does the Ocular Adnexa include?

• Eyebrows

• Eyelids

• Eyelashes

• Conjunctive

• Lacrimal system

• Extraocular muscles

• Orbital contents

Eyebrows

• Thick skin

• Short, coarse hair

• Extend across superior orbital rim

Where are the eyebrows located?

Extend across superior orbital rim.

How many eyebrow muscles are there?

Three.

What are the the eyebrow muscles?

• Frontalis

• Procerus

• Corrugator

What nerve innervates the eyebrow muscles?

Cranial nerve VII (facial nerve).

What do eyebrow muscles help control?

Facial expressions.

Where is the origin of the Frontalis muscle?

Superior scalp.

Where is the insertion of the frontalis muscle?

Connective tissue near superior orbital rim.

What is the function of the frontalis muscle?

Raises eyebrows.

(Horizontal wrinkles in forehead; i.e. surprised)

Where is the origin of the Corrugator muscle?

Inferomedial frontal bone.

Where is the insertion of the corrugator muscle?

Skin superior to medial eyebrow.

What is the function of the corrugator muscle?

Moves eyebrows inferomedially.

• Vertical frown lines

• “Concentration” or “concern”

Where is the origin of the procerus muscle?

Nasal bone.

Where is the insertion of the procerus muscle?

Medial frontalis.

What is the function of the procerus muscle?

Pulls medial eyebrow inferiorly.

• Horizontal furrows along bridge of nose.

• “Menace” or “aggression”.

Eyelids

Folds of skin and tissue that cover the globe when closed.

Thinnest skin in the body.

What is the thinnest skin in the body?

Eyelids.

What are the functions of the eyelids?

• Protection of globe

• Contain structures that produce the tear film.

• Spread tear film over anterior ocular surface. (upon opening)

• Move tears toward drainage areas at medial canthus. (upon closing)

What happens upon opening of the eyelids?

Tear film is spread over the anterior ocular surface.

What happens upon closing of the eyelids?

Moves tears toward drainage areas at medial canthus.

Eyelid Histology

• Epidermis

• Dermis

• Subcutaneous connective tissue

• Orbicularis oculi muscle

• Orbital septum

• Levator muscle / tarsal muscles

• Tarsal plate

• Conjunctiva

What are factors that make eyelids more susceptible to inflammation, infection, fluid accumulation and injury?

• Thin skin

• Loose connective tissue

• Many elastic fibers

• Reduced adipose tissue (in tarsal portion)

Do the eyelids contain high levels of adipose tissue?

NO. But they have orbital fat pads that surround the eyelids.

How many parts does the upper eyelid consist of?

Two.

What are the parts of the upper eyelid?

• Tarsal portion

• Orbital / Preseptal portion

What does the tarsal portion of the upper eyelid consist of?

• Little adipose tissue

• Contains tarsal plate

• Rests on globe

• Adjacent to lid margin

Where is the orbital / preseptal portion of the upper eyelid?

Adjacent to eyebrow.

What is the superior palpebral sulcus?

Separates the tarsal portion from the orbital portion?

How many parts is the lower eyelid divided in?

Two.

What is the tarsal portion of the lower eyelid?

• Adjacent to lid margin

• Rests on globe

• Contains tarsal plate

Where is the orbital / preseptal portion of the lower eyelid?

Extends onto cheek.

What is the inferior palpebral sulcus?

Separates the tarsal portion from the orbital portion.

(Not usually as distinct as superior.)

Eyelid Margins

Edges of eyelids.

Where are the eyelid margins located?

Rests against the globe.

What does the eyelid margin consist of?

• Cilia (eyelashes)

• Meibomian gland pores

How many divisions does the eyelid margin have?

Two.

What are the divisions of the eyelid margin?

• Lacrimal

• Ciliary

Lacrimal division (eyelid margin)

• Medial 1/6th

• No cilia

Ciliary division (eyelid margin)

• Lateral 5/6th

• Contains cilia

Where does the eyelid margin division occur?

Lacrimal papilla.

Eyelid Margin Structures

• Cilia (most anterior)

• Gray line

• Meibomian gland pores

• Mucocutaneous junction (line of Marx) (most posterior)

Gray Line (eyelid margin)

• Divides eyelid into anterior / posterior

  • Surgical landmark

• Most superficial portion of Riolan muscle

  • Part of orbicularis oculi muscle

What is the most superficial portion of the Riolan muscle?

Gray line.

Mucocutaneous Junction (line of Marx)

• Keratinized, stratified squamous epithelium of skin meets non-keratinized conjunctival epithelium.

Cilia / Eyelashes

Highly innervated for protection (blinking)

• Shed and grow in continuous cycle.

How many eyelashes/cilia are in the upper lid?

• ~ 150 in 2-3 rows

• Curl upwards

How many eyelashes/cilia in lower lid?

• ~75 in 1-2 rows.

• Curl downwards

What is the ENTIRE cycle time for eyelash growth?

~ 4 - 11 months.

How long is the growth phase for eyelashes?

(anagen) = 4 - 10 weeks OR about 2 months

Examples of Eyelash Abnormalities

• Madrosis (loss of lashes

• Trichasis (misdirected growth of lases)

• Distichiasis: Extra rows of lashes

• Poliosis: Whitening of lashes

Palpebral Fissure

Area between open eyelids.

• Upper eyelid normally covers the superior corneal limbus by 1.5-2mm.

What is the average palpebral height (PFH)?

• Caucasian: 11mm

• Asian: 8.5mm

Marginal Reflec Distance 1 (MRD1)

(Part of palpebral fissure)

Distance between corneal reflex and upper eyelid margin.

~4 - 5mm

Marginal Reflex Distance 2 (MRD2)

(part of palpebral fissure)

Distance between corneal reflex and lower eyelid margin.

~5 - 5.5mm

Structures in the Medial Canthus

• Plica semilunaris

• Lacrimal lake

• Caruncle

• Lacrimal punctum (or puncta; plural)

What does the medial canthus help with?

Tear drainage

What is the plica semilunaris?

A narrow, crescent-shaped fold of bulbar conjunctiva.

Serves as the floor for the lacrimal lake.

What is the function of the plica semilunaris?

Allows for lateral eye movement.

Where is the lacrimal lake located?

In the medial canthus.

What is the lacrimal lake?

• Small reservoir of tears.

• Separates medial canthus from globe.

Where is the caruncle located?

Medial Canthus.

What is the caruncle?

Small, pink mass of modified skin (combination of epidermis and conjunctiva).

Where is the carnucle located?

Medial to the plica semilunaris.

Highly innervated**

What is the canthus?

Corners of the palpebral fissure where upper and lower eyelids meet.

Where is the canthus located?

Located medially and laterally.