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Questions and Answers
What is one of the primary functions of the eyelids in relation to eye health?
What is one of the primary functions of the eyelids in relation to eye health?
During which time frame does eyelid fusion occur during gestation?
During which time frame does eyelid fusion occur during gestation?
Which embryonic structure contributes to the formation of lower eyelids?
Which embryonic structure contributes to the formation of lower eyelids?
What is the role of eyelids in light regulation?
What is the role of eyelids in light regulation?
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Which of the following best describes the protective function of eyelids?
Which of the following best describes the protective function of eyelids?
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At what stage of gestation do eyelid structures begin to fully develop?
At what stage of gestation do eyelid structures begin to fully develop?
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What is the main purpose of the blink reflex?
What is the main purpose of the blink reflex?
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What layer forms the eyelids from the embryological development perspective?
What layer forms the eyelids from the embryological development perspective?
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What is the diameter of the horizontal palpebral aperture at birth?
What is the diameter of the horizontal palpebral aperture at birth?
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Which nerve is responsible for the motor supply to the orbicularis oculi muscle?
Which nerve is responsible for the motor supply to the orbicularis oculi muscle?
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What type of gland opens at the lid margin?
What type of gland opens at the lid margin?
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Which layer of the eyelids is innermost and contains small accessory lacrimal glands?
Which layer of the eyelids is innermost and contains small accessory lacrimal glands?
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What is the primary artery responsible for the arterial supply of the eyelid?
What is the primary artery responsible for the arterial supply of the eyelid?
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Which condition is characterized by abnormal growth or misdirection of eyelashes?
Which condition is characterized by abnormal growth or misdirection of eyelashes?
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What is the function of the Müller muscle?
What is the function of the Müller muscle?
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What is the venous drainage of the eyelid primarily divided into?
What is the venous drainage of the eyelid primarily divided into?
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What type of inflammation characterizes an external hordeolum?
What type of inflammation characterizes an external hordeolum?
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What is a common characteristic of a chalazion?
What is a common characteristic of a chalazion?
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Which type of blepharitis affects the base of the eyelashes?
Which type of blepharitis affects the base of the eyelashes?
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What distinguishes seborrheic blepharitis from other types?
What distinguishes seborrheic blepharitis from other types?
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What is the correct term for the condition characterized by eyelid dysjunction occurring at 5 to 6 months gestation?
What is the correct term for the condition characterized by eyelid dysjunction occurring at 5 to 6 months gestation?
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Which anatomical portion of the upper eyelid is located closest to the eyebrow?
Which anatomical portion of the upper eyelid is located closest to the eyebrow?
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What is a symptom of posterior blepharitis?
What is a symptom of posterior blepharitis?
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What separates the orbital portion from the tarsal portion in the upper eyelid?
What separates the orbital portion from the tarsal portion in the upper eyelid?
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Which condition is characterized by redness and peripheral corneal infiltrates?
Which condition is characterized by redness and peripheral corneal infiltrates?
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In the lower eyelid, which portion transitions smoothly into the cheek?
In the lower eyelid, which portion transitions smoothly into the cheek?
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What is the cause of parasitic blepharitis?
What is the cause of parasitic blepharitis?
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Meibomitis is specifically characterized by which of the following?
Meibomitis is specifically characterized by which of the following?
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Which structure is less pronounced in the lower eyelid compared to the superior sulcus?
Which structure is less pronounced in the lower eyelid compared to the superior sulcus?
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Study Notes
Anatomy & Physiology of the Eyelids
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Eyelid importance:
- Protect eyes from foreign objects
- Spread tears for lubrication
- Regulate light entering the eye
- Contribute to facial aesthetics and expressions
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Embryology:
- Develop from surface ectoderm
- Upper eyelids form from the frontonasal process
- Lower eyelids form from the maxillary process
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Eyelid development timeline:
- 6-7 weeks: Appearance of eyelid fold
- 8-10 weeks: Eyelid fusion
- 3-4 months: Development of eyelid structures
- 5-6 months: Eyelid reopening
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Common congenital eyelid anomalies:
- Ectropion: Outward turning of the eyelid
- Ankyloblepheron: Fusion of eyelids
- Lid Coloboma: Missing portion of the eyelid
- Cryptophthalmos: Buried eyeball under the skin
- Entropion: Inward turning of the eyelid
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Clinical correlation:
- Blepherophimosis: Narrow palpebral fissure
- Epiblepheron: Fold of skin obscuring the eyelashes
- Epicanthus: Fold of skin covering the inner eye
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Eyelid anatomy:
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Upper eyelid: Composed of orbital, tarsal, and marginal portions
- Superior palpebral sulcus: Groove that separates the orbital and tarsal portions
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Lower eyelid: Composed of orbital, tarsal, and ciliary portions
- Inferior palpebral sulcus: Less prominent groove that separates the orbital and tarsal portions
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Upper eyelid: Composed of orbital, tarsal, and marginal portions
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Palpebral fissure (eyelid opening):
- At birth: Horizontal diameter 18-21 mm, Vertical diameter 8mm
- Adult: Horizontal diameter 28-30 mm, Vertical diameter 9-11 mm
- Medial canthus (inner corner of the eye): Consists of Lacrimal Caruncle, Plica Semilunaris and the medial palpebral ligament
- Lid margin: The free edge of the eyelid comprised of cilia, openings of glands of Moll and Zeiss, and the meibomian gland openings.
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Clinical Correlation of lid Margin glands:
- Cyst of Moll/Cyst of Zeiss: cysts arising from the obstruction of their respective glands.
- Distichiasis: Abnormal growth of eyelashes from the meibomian gland openings.
- Trichiasis: Eyelashes misdirected toward the eye.
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Layers of the eyelid:
- Skin and subcutaneous areolar tissue
- Muscles of protraction and retraction
- Orbital septum
- Orbital fat
- Tarsus
- Conjunctiva: Innermost layer that lines the posterior surface of the eyelids and the anterior surface of the globe.
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Nerve supply:
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Motor:
- Orbicularis oculi: Facial nerve
- Levator palpebrae superioris: Superior division of oculomotor nerve
- Müller's muscle: Sympathetic nervous system
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Sensory: Ophthalmic and maxillary divisions of the trigeminal nerve
- Upper eyelid: Supraorbital, supratrochlear, and lacrimal nerves
- Lower eyelid: Infraorbital nerve
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Motor:
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Arterial Supply:
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Marginal arcade: In front of the tarsal plate
- Lateral palpebral artery (from lacrimal artery)
- Medial palpebral artery (from dorsal nasal artery)
- Peripheral arcade: Upper border of the tarsus
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Marginal arcade: In front of the tarsal plate
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Venous drainage: Pretarsal and postarsal systems
- Pretarsal: Subcutaneous veins, angular vein, superficial temporal vein
- Postarsal: Orbital veins, ophthalmic vein, cavernous sinus
- Eyelid retractors: Levator palpebrae superioris, Müller's muscle
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Glands of the eyelid:
- Meibomian glands: Sebaceous glands within the tarsal plate
Clinical correlation of eyelid glands:
- External hordeolum (stye): Localized infection of the glands of Zeis and Moll.
- Internal hordeolum: Infection of the meibomian gland.
- Chalazion: Chronic granulomatous inflammation of meibomian glands due to retained sebaceous secretions.
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Blepharitis: Inflammation of the lid margin.
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Anterior blepharitis: Affects the base of eyelashes.
- Staphylococcal: Associated with atopic dermatitis.
- Seborrhoeic: Associated with dandruff.
- Parasitic: Due to crab louse.
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Posterior blepharitis: Affects the meibomian glands.
- Meibomitis: Obstruction and inflammation of meibomian glands, often secondary to posterior blepharitis.
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Anterior blepharitis: Affects the base of eyelashes.
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Description
This quiz covers the anatomy and physiology of the eyelids, including their developmental timeline and the importance of eyelids in protecting the eyes. Additionally, it explores common congenital anomalies associated with eyelids and their clinical correlations. Test your knowledge on the intricate details and functions of this vital facial feature.
