Eyelids Flashcards
What are the five main components of the eyelid?
Skin Orbicularis oculi fibrous layer Levator palpebrae superioris muscle Muller muscle
What is the skin adnexa and what are its components?
The adnexa lies deep to the dermal layer of the eyelid and includes the eyelashes, eccrine, apocrine and holocrine glands.
Where is the upper eyelid located?
2mm inferior to the superior limbus
Where is the lower eyelif located?
Sits on the inferior limbus border
What is the role of the eccrine glands?
These are the sweat glands of the eyelid
What do the holocrine glands secrete? Give some examples of holocrine glands q
Lipids and oily substances
Meibomian glands
Gland of Zeis
What are the apocrine glands?
E.g. gland of moll
These are modified sweat glands
What is the sensory supply to the upper eyelid?
Laterally - lacrimal nerve (CNV1)
Medially - Supraorbital and Supratrochlear nerves (these are branches of the frontal nerve CNV3)
What is the sensory supply to the lower eyelid?
Infraorbital nerve - branch of CNV2
What is the sensory supply to the medial canthal area of the eyelids?
Infratrochlear nerve - this is a branch of the nasociliary nerve of CNV1
What is the name of the striated muscle whose main function is to close the eye?
The orbicularis oculi
What are the four segments of the orbicularis oculi?
Palpebral
Orbital
Lacrimal
Ciliary
What nerves supply the orbicularis oculi?
Temporal and Zygomatic branches of CNVII
The fibrous layer is split into the tarsal plate and the orbit septum. What are the functions of the tarsal plate?
Tarsal plate: Structural support to the eyelids
What muscle is responsible for eyelid retraction?
Levator palpebrae superioris
What is the origin and insertion for the Levator palpebrae superioris
Origin - lesser wing of the sphenoid
Inserts - tarsal plate
What is the nerve supply to the Levator palpebrae superioris
CN III superior division
Give the name of a smooth muscle, which has sympathetic innervation, that contributes to eyelid retraction?
Muller Muscle
Where does the Muller muscle originate and insert?
Origin - Levator aponeurosis
Insert: tarsal plate
List the three ways the blinking reflex can be stimulated:
Corneal stimuli
Light stimuli
Auditory stimuli
How is the corneal stimuli elicited?
Afferent - CNV1
Efferent - CNVII
How is the light stimuli elicited?
Afferent - CN II
Efferent - CN VII
How is the auditory stimuli elicited?
Afferent - CNVIII
Efferent - CNVII
Define Bell’s phenomenon:
This is a physiological term describing the upward and outward rotation of the globe during forced lid closure. It is considered a defence mechanism.
When might Bell’s phenomenon be easily observed?
In CNVII palsy. The lid will remain open when the patient is asked to close their eyes.