ORBIT & OCULAR ADNEXAE - Eyelids Flashcards
What is the grey line of the eyelid? What does it divide?
Gray line divides the eyelid margin into the anterior lamina and posterior lamina
Anterior to tarsal plate
Posterior to lash line.
What is the difference between the gland of zeiss and the gland of moll in terms of
1. Location
2. Lobularity
3. Function
- Zeiss : at the margin of the eyelid,
Moll: between cilia (eyelash) and anterior lid margin - Zeiss: unilobular
Moll: unbranched spiral shape - Zeiss: modified sebaceous gland that produces sebum to prevent eyelashes from becoming dry and brittle
Moll: apocrine sweat gland
What is the horizontal and vertical measurement of the palpebral fissure?
horizontal - 30mm
vertical - 10mm
What is a mongoloid slant? Which strabismus pattern does it exhibit
Elevation of lateral canthus > 2mm
Pseudo A pattern strabismus
What conditions have mongoloid slant?
Down’s syndrome
Noonan’s syndrome
What conditions have Anti-mongoloid slant? What strabismus pattern?
Treacher collin syndrome
Coffin lowry syndrome
Zygomatic maxillary complex fracture
Pseudo V pattern strabismus
What are the 9 layers of the eyelid from outside to inside?
- Skin - v thin loosely adhered to muscle
- Subcutaneous areolar tissue - only fat
- Striated muscle layer (orbicularis)
- Submuscular areolar tissue
- Fibrous layer (tarsal plate and orbital septum)
- Orbital Fat
- Levator Aponeurosis
- Non-striated muscle layer - Muller’s muscle
- Conjunctiva
What are the two parts of the orbicularis muscle? What is their function?
- Orbital part - forced closure of eyelid
- Palpebral part - gentle closure of eyelid
Which layer consists of the nerves and vessels of the eyelid? What does this layer connect with?
Submuscular areolar tissue
Communicates with striatum of scalp - dangerous area of scalp and can act as communication for pus/blood between two areas
What is the tarsal plate?
Dense fibrous tissue of the eyelid giving strength and firmness, has meibomian glands embedded within it
What is the upper and lower tarsal height?
Upper : 10mm
Lower: 5mm
How many meibomian glands are there?
20-30 on each lid
What do meibomian glands produce?
Sebaceous glands (like Zeiss glands) Produce lipids (meibum) that forms the outer layer of tear film to stop evaporation
What is attached to the superior tarsal border? (2)
What structure is attached below the superior tarsal border?
1.Orbital septum and muller’s muscle
2. LPS aponeurosis attaches 3-4mm below,
What is attached to the inferior tarsal border? (3)
Orbital septum
capsulopalpebral fascia
inferior palpebral/tarsal muscle (lockwood ligament) which connects to the inferior rectus
What are the lateral ends of the tarsus attached to?
What are the medial ends of the tarsus attached to?
Lateral: whitnal tubercle by lateral palpebral ligament
Medial: attach to anterior lacrimal crest and frontal process of maxillla by medial palpebral ligament
What is the muller’s muscle and inferior palpebral muscle innervated by?
sympathetic nerve fibres – irritation leads to retraction of lids –> paralysis leads to horner’s syndrome
What is the difference between cyst of zeiss and cyst of moll?
Zeiss: non-translucent, obstructed sebaceous gland with eyelash follicle (picture)
Moll: Translucent - retention cyst of apocrine sweat gland
Which nerve supplies the upper lid (4)
Which nerve supplies the lower lid (2)
Upper: Infratrochlear, Supratrochlear, Supraorbital, Lacrimal
Lower: Infraratroclear, Infraorbital.
What is the origin and insertion of Muller’s muscle?
Origin: Underside of LPS
Route: Travels inferiorly between levator aponeurosis and conjunctiva
Insertion: Inserts into superior border of tarsus
Where is the origin and insertion of the LPS? What happens to its medial horn?
Origin: Lesser wing of sphenoid bone above the optic canal
Insertion: Superior tarsal plate.
Medial horn of aponeurosis inserts into frontolacrimal suture.
When do the eyelids form embryologically?
4-5 weeks upper eyelid forms first from surface ectoderm
What are the 4 layers of the epidermis?
Superficial to deep
1. Keratin layer (stratum corneum) - devoid of nuclei.
2. Granular layer (stratum granulosum) - keratohyaline granules
3. Prickle cell layer (stratum spinosum) - polygonal cells 5 cell layers thick with eosinophilic cytoplasm joined by desmosomes
4. Basal cell layer (stratum basale) - single row of cells, contain melanin/melanocytes
Extra layer: Stratum lucidum (found between corneum and granulosum - found in palms/soles)
How does entropion occur?
Laxity of tissue causes Relative dissociation of anterior lamella (skin + orbicularis) and posteiror lamella (tarsus, conjunctiva, lid retractors)
Leads to upward movement of anterior lamella and preseptal orbicularis muscle with weakness of lower lid retractors
There is horizontal lid laxity with medil and lateral canthal relaxation, leading to tarsal stretching
