seven of them!

1. Roof: frontal bone
2. Lateral wall: zygomatic, sphenoid bone
3. Floor: maxillary bone (MC orbital fracture)
4. Medial wall: lacrimal and ethmoid
   

• pyramid shaped. Base=orbial margin. Apex=optic canal.
• medial wall are parallel.
• lateral wall are 90 degree
• optical axes are parallel
• orbital axes are 45 degree

where does sueprior recturs

lateral rectus

inferior rectus

and superior/inferior oblique come from?

Motion of eyes lid?

what is the fx of orbicularis Oculi?

what is the fx of levator palpebrae superioris?

what innervate orbucularis oculi and what innervate levator palpebrae superioris?

• orbicularis oculi: closes the eyes lid (CN7-look like hook that pull eyes shut). Bell's palsy
• levator palpebrae superioris: opens the eyelids (CN3- three pillars III keep eyes open). Ptosis (can't open eyes)
  

• superior, inferior, medial and lateral
• originated from annulus tendineus (Annulus of Zinn)
• Insertion: sclera, posterior cornea.

Lateral (abducent N), superior Obl (trochlear N), Medial (superiod division of oculomotor), inferior (inferior devision of oculomotor)

• origin: frontal bone, medial palpebral ligament, lacrimal bone
• Insertion: lateral palpebral raphe.
• Orbital portion: tight closure
• palpebral portion: blinking
• innervation: temporal and zygomatic branch of facial n VII

• origin: lesser wing of sphenoid
• insertion: superior tarsus and superial fascia of the eye lid
• contains smooth muscle fibers (superior tarsal or Muller's muscles)

• Superior oblique:

1. origin: lesser wing of sphenoid bone
2. pass through trochlea
3. insert into sclera deep to superior rectus

• Inferior oblique

1. origin: medial orbital wall
2. passes posterolateraly beneath eyeball
3. insert into sclera deep to lateral retus.

• Mc: orbital floor, even though medial wall is more fragile.
• Maxillary bone fractures downward and contents can herniate into maxillary sinus. Sinus and bone absorn the force, eyes are protected.
• orbital fractures heal fine, but bone can break and trap nerve underneath.

SO4 LR6 AO3

Superior Oblique CN IV  (trochlea)

Lateral rectus CN VI (abducent)

All other CN III (oculomotor)

super tarsal (muller's ) muscle: postganglionic sympathetics from superior cervical ganglion.

1. Horizontal: elevation and depression axis
2. vertical: abduction and adduction axis
3. anteroposterior (optic axis)intorsion and extorsion (in and out)

move the optical axis

use a combination of muscles

Action to eliminate torsion using lateral rectus

with contracting superior rectus

pulling superior rectus will rotate the eye (do not want torsion)

using lateral rectus will Abduct the eyes and correct it

= eyes elevated laterally

lateral rectus contraction will bring eye laterally

inferior rectus contraction bring eyes inferiorly

eyes depressed laterally

eliminate torsion using medial rectus

with superior oblique involvement

medial rectus contraction pull eyes medially

superior oblique contraction will pull eyes inferiorly

eyes depressed medially.

medial rectus pull eyes medially (adducted)

inferior oblique will pull eyes superiorly

eyes elevates medially

1. superior rectus: strong elevator of                          
2. Inferior rectus: strong depressor of                         
   
3. Inferior oblique: strong elevator of                         
4. Superior oblique: strong depressor of                      

1. already abducted eyeball (by lateral rectus)
2. already abducted eyeball (by lateral rectus)
3. already adducted eyeball (by medial rectus)
4. already adducted eyeball (by medial rectus)

1. superior rectus + inferior oblique=                          
2. inferior rectus + superior oblique=                         

1. elevation
2. depression

• superior rectus: strong elevator of already abducted eyeball
• inferior rectus: strong depressor of already abducted eyeball
• inferior oblique is strong elevator of already adducted eyeball
• superior oblique is strong depressor of already adducted eyeball

Depression and elevation without torsion

• superior rectus+ inferior oblique= elevation
• infrior rectus + superior obluqe = depression

CN VI: Abducent nerve

RO4LR6AO3

this is a Lateral rectus defect

unable to abduct the eyeball

may turn head to avoid double vision

CN VI is susceptible to high intracranial pressure

CN III: oculomotor nerve

eye deviates "down and out"

levator palpebrae superioris-->ptosis, eyes cannot open

may also have blown pupul : ischemic vs compressionve (parasympathetic)

• CN IV trochear nerve innvervates Superior Oblique, neck pain
• tend to tilt head away from lesion to compensate for torsion (Bielschowsky's sign)-action of superior rectus alone for intorsion causes elevation of affected eyes.