PTOSIS

               Ptosis is drooping of the eye lid. We need to know that 3rd CN that innervates the levetor palpebrea muscle. 

Aprroach to ptosis:

1. Unilateral vs bilateral eyes
2. Look at the pupils
3. Eye movement and squint.
4. Sympathetic innervation

1. Unilateral vs bilateral 

Unilateral (then check pupil-sympathetic innervation 3rd CN)

• small pupil - Horner's syndrome
• normal pupil - medical 3rd CN palsy, DM
• large pupil - Surgical 3rd CN palsy, here 2 conditions is considered:(if isolated - PCOM aneurysm, if combine; 3, 4, 6 th CN palsy - carvenous sinus or superior orbital fissure syndrome) 

Bilateral 

• small pupil - horner's syndrome
• normal pupil - (think of neuromuscular jnt and muscle) - MG, dystrophia myotonica & Kearns- Sayre syndrome. *, DM
• large pupil - bilateral 3rd nerve palsy and midbrain lesion.

* progressive external opthalmoplegia , characterised by reduce eye movement, retinitis pigmentosa, prolonged PR interval.

3. Eye movement (H movement yeah)

abduction - 6th CN (LR6)

downward - 4th CN (SO4), absent of intortion of eye. (D, I) 

* vertical eye has additional action (intortion and extortion)

the rest is 3rd CN - adduction,  downward and upward.

( need to know origin, distribution and innervation of 3,4,6 th CN) -??

then, need to know the origin : divide by:

• supranuclear Opthalmoplegia - abnormal conjugate gaze ( horizontal (pons) or vertical(midbrain)) show doll eye sign.
• nuclear and infranuclear opthalmoplegia - diplopia, doll's eye response absent.

4. Sympathetic innervation