Lecture 2 Flashcards
1
Q
A
2
Q
A
3
Q
The orbit
A
The orbit is developed around the eye. It is roughly the shape of a quadrilatereal pyramid. The apex is at the optic foramen (optic nerve), and the base at the orbital margins.
4
Q
Conditions affecting the orbit
A
- Any large mass in the orbit will cause protrusion or displacement of the eye = proptosis
- Swelling of orbit contents (muscle) such as in thyroid eye disease will also cause proptosis (exophthalmos)
5
Q
Orbital bone fractures: Blow-out fractures
A
- Outward signs of haeorrhage
- Have to avoid a hit to the eye
- Orbital fat and EOM can become entrapped in the fracture.
6
Q
Foramen, fissure for nerve and blood vessel
A
7
Q
The optic foramen
A
The optic foramen facilitates for the optic nerve, ophthalmic artery, central retinal vein which traveks within the optic nerve out of the eye.
8
Q
A
9
Q
Which muscles are connected to movement of the eyelids?
A
- Levator palpebrae
- Orbicularis Oculi
10
Q
General structure of the eyelids
A
- The lid is a mobile and complex structure
- The structure of the lids including the tarsal plates and muscles causes characteristics folds and furow
- Caruncle = modified skin
11
Q
Eyelids- Tarsal plates
A
- Two thin plates
- One in upper and lower lid
- Dense connective tissue
- Provide structure to the lids
12
Q
Levator palpebral
A
- The Levator palpebral lifts the upper lid
- Starts from the sphenoid bone
- Runs horizontally forwards
- Lies between the superior rectus (an EOM) and the roof of the orbit
- At its end, the muscle fans out into a wide aponeurosis
- It passes into the tarsal plate of the upper eyelid.
13
Q
The lower lid
A
- There is close association with the inferior oblique muscle
14
Q
Orbicularis Oculi
A
- Has 3 parts: orbital, palpebral & lacrimal
- The orbital part is the largest
- It extends onto the face some distance beyond the orbital rim
- Some upper fibres are inserted into the eyebrow
- These depress the eyebrow
- The fibres of the muscle pass around the orbit in concentric loops
- The palpebral portion is the central part & is confined to the eyelids
15
Q
Ptosis
A
- Droopy eyelid
- Can be congenital due to absence or poor levator function
- On down-gaze the levator may not relax and so the lid is ‘thethered’ up
- Can also be a sign of paralysis (3rd nerve)
16
Q
Entropion
A
- Entropion is the turning in or inversion of the lid
- Also turns the eyelashes towards the eye - watery eye
- Over time can cause scarring of the cornea, therefore visual impairment
17
Q
Ectropion
A
- Ectropion is the turning out or eversion of the lid, usually the lower lid
- Causes the eye to ‘weep’
- Can cause dry eye
- Congenital
- More common with age
