1. Frontal Bone
2. Nasal Bone
3. Maxilla
4. Mandible
5. Zygomatic Bone
6. Sphenoid Bone
7. Temporal Bone
8. Parietal Bone
9. Occipital Bone 

1. Roof
2. Floor
3. Apex
4. Medial Wall
5. Lateral Wall 

1. Frontal Bone
2. Zygomatic
3. Maxillary
4. Palatine
5. Lacrimal
6. Ethmoid
7. Sphenoid 

1. Greater wing of Sphenoid
2. Superior orbital fissure
3. Lesser wing of sphenoid
4. Frontal bone
5. Optic canal
6. Ethmoidal foramina
7. Ethmoid bone
8. Lacrimal bone
9. Palatine bone
10. Maxilla
11. Inferior orbital fissure
12. Zygomatic bone

• Lesser Wing of Sphenoid
• contains optic canal w/ optic nerve & opthalmic artery

1. optic canal
2. superior orbital fissure
3. inferior orbital fissure
4. infraorbital foramen
5. ethmoidal foramina 

• most nerves supplying the orbit & its contents
• superior ophthalmic vein

• infraorbital nerve
• inferior ophthalmic vein

• lined w/ respiratory mucosa (ciliated & secretes mucus)
• filled w/ air
• communite w/ & drain in nasal cavity through small aperatures 

• located above the orbit & contained w/n frontal bone
• 2 are separated by bony septum
• triangular, extends up above medial eyebrow end & backward into orbit roof

• located below the orbit & w/n body of Maxilla bone
• roof formed by floor of the orbit
• pyramidal in shape

• located medial to the orbit & w/n body of sphenoid
• each of 2 opens into sphenoethmoidal recess (nasal cavity) abover superior concha

• located medial to the orbit & w/n ethmoid bone b/n nose & orbit
• separated from orbit by thin plate of bone (lamina papyracea) 

• act as resonators to the voice
• reduce the weight of the skul

1. Lacrimal gland
2. Lacrimal ducts
3. Canaliculi
4. Lacrimal sacs
5. Nasolacrimal duct

1. Periorbita
2. Tenon's Capsule
3. Suspensory Ligament (of Lockwood)
4. Orbital septum
5. Check ligaments
6. Extraocular muscle pulleys
7. Orbital fat

Define Periorbita:

(aka orbital periosteum/orbital fascia)

• dense CT that lines the bones in the orbit
• attachment for muscles & ligaments
• provides support for blood vessels

Define Tenon's Capsule:

(aka Fascial Sheath/Fascia Bulbi)

• condensation of fibrous tissue
• covers eyeball from entrance of optic nerve to near corneal limbus
• perforated by tendons of EOM
• serves as socket for prosthetic eye

• fills the spaces not occupied by ocular structures
• cushions & protects ocular structures

thin, transparent mucous membrane

Palpebral & Bulbar

• Palpebral - lines posterior surface of eyelid
• Bulbar - covers anterior part of eyeball

What is the aqueous portion of the eyeball?

• the clear fluid that fills the anterior & posterior chambers of the eye
• secreted by the ciliary body

• maintains intra-ocular pressure (IOP)...clinically correlates to Glaucoma
• nurtures avascular cornea & lens

• clear, avascular & gel-like body that fills postremal (vitreal) chamber
• 2/3 weight & volume of eyeball
• does not regenerate

• biconvex, avascular, clear, pure epithelial tissue
• posterior to iris & connected to ciliary body by zonules
• accommodation...clinically correlates to Cataracts & Glaucoma

cornea & sclera

• mainly through opthalmic artery (branch of internal carotid artery)
• enters orbit through optic canal

• MR, LR, SR, IR, SO, IO
• Levator palpebrae superioris
• superior tarsal muscle (Muller's muscle) 

• CN III
• Adduction 

• CN VI
• Abduction

• CN III
• Elevation
• also intorsion & adduction

• CN III
• Depression
• also extorsion & adduction

• CN IV
• Intorsion
• also depression & abduction

• CN III
• Extorsion
• also elevation & abduction

• 6 striated muscles that act on the eyeball & are external to the eye
• move the eyeball
• support eye globe during head movement

• anterior aspects of bony orbit (medial wall)
• from periorbita of inferonasal orbital rim adjacent to the anterior lacrimal crest

• orbital apex
• periorbita of superonasal orbital wall (slightly anterior to recti)

• condensation of fibrous tissue that covers eyeball from entrance of optic nerve to near corneal limbus
• fascia bulbi is perforated by tendons of EOMs

• fastest & precise movements
• structure & associated CT is specialized for unique functional requirements

In what ways do EOMs differ from all other striated muscles?

(compared to typical skeletal muscle...)

• CT in EOMs more delicate & has higher # of elastin fibers
• higher vascular supply
• distinct orbital & global layers
• presence of single innervated (SIFs) & multiple innervated fibers (MIFs)...MIFs unique to EOMs
• wide variety of myosin isoforms

• elevation or supraduction
• depression or infraduction

• Abduction or lateral movement
• Adduction or medial movement

• inward rotation (intorsion or incycloduction)
• outward rotation (extorsion or excycloduction)

• convergence - both eyes adducted
• divergence - both eyes abducted

• right & left gazes
• supraversion
• infraversion

antagonist

• LR & MR
• SR & IR
• SO & IO

• vertical recti (SR & IR)
• 2 oblique (SO & IO)

• intorsion (SO + SR)
• extorsion (IO + IR)
• elevation (IO + SR)
• depression (SO + IR)

• adduction (MR + SR + IR)
• abduction (LR + SO + IO)

• Ophthalmic artery
• Optic nerve (CN II)
• Oculomotor nerve (CN III)
• Nasociliary nerve (branch off CN V₁)
• Abducens nerve (CN VI)

• Olfactory
• sensory nerves of smell

• Optic Nerve
• sensory nerve of vision

• Oculomotor Nerve
• innervates four of extrinsic eye muscles

• Trochlear Nerve
• innervates the superior oblique extraocular muscle

• Trigeminal Nerve
• provides sensory innervation to the face 
• provides motor innervation to the muscles of mastication

• CN V₁: Ophthalmic - sensory innervation to orbit (enters through superior orbital fissure)
• CN V₂: Maxillary
• CN V₃: Mandibular

• Abducens Nerve
• abducts the eyeball 
• supplies LR

• Facial Nerve
• complex nerve including motor, sensory, & parasympathetic fibers 
• innervates muscles of facial expression; sensory innervation of face
• corneal reflex 
• taste in anterior 2/3rds of tongue
• parasympathetic innervation of lacrimal & 2 salivary glands

• Vestibulocochlear Nerve
• sensory nerve of hearing & balance

• Glossopharygeal Nerve
• sensory & motor innervation of structures of tongue & pharynx
• taste
• parasympathetic fibers

• Vagus Nerve
• mixed sensory & motor nerve
• main parasympathetic nerve
• only 1 to wander into thorax & abdomen

• Accessory Nerve
• somatic motor neck muscles
• trapezius & SCM

• Hypoglossal Nerve
• runs inferior to the tongue
• innervates tongue muscles; motor

• Olfactory (CN I)
• Optic (CN II)
• Vestibulocochlear (CN VIII)

• Oculomotor (CN III)
• Trochlear (CN IV)
• Abducens (CN VI)
• Accessory (CN XI)
• Hypoglossal (CN XII)

• Trigeminal (CN V)
• Facial (CN VII)
• Glossopharyngeal (CN IX)
• Vagus (CN X)

• attach to the brain
• pass through foramina of skull

• primarily serve head & neck structures
• exception: Vagus nerve (X) extends into the thorax & abdomen

• relatively large
• low muscle fiber to nerve fiber ratio
• precise movements

• interconnected
• receive fibers from both cerebral hemispheres & from visual cortex

• superior rectus
• levator palpebrae superioris

• medial rectus muscle
• inferior rectus muscle
• inferior oblique muscle

• emerges from midbrain from the posterior aspect of the brain stem
• decussates with the nerve of the opposite site

• enters the orbit though SOF b/n superior & inferior divisions of CN III (inside oculomotor foramen)
• reaches lateral rectus muscle

Each EOM has a ________________

in the opposite eye that allows symmetric eye movements.

• compression
• reduced blood supply
• diabetes
• traumatisms, congenital

• deficit in ocular motility
• ptosis (CN III)
• dilatation of pupil (CN III)
• compensatory position of head (tilts)

• complete lesions: weakness of muscles innervated by CN III
• result: ptosis of lid, mydriasis, & outwardly turned eye during primary gaze
• diplopia - no accommodation
• upward & downward gaze compromised in affected eye
• SO causes eye to rotate inward during downward gaze

• partial lesions: affect either EOMs or intraocular muscles
• EOM affected w/o parasympathetic involvement
• intraocular muscles affected w/o EOM involvement

• weakness of SO muscle innervated by CN IV
• difficult to detect b/c affect vertical eye position when eye turned inward
• diplopia
• patient tilts head to side opposite of palsy or toward unaffected eye

• weakness of LR muscle innervated by CN VI
• eye turned inward; moves outward sluggishly reaching midline at most

• recurring episodes of intense stabbing pain in CN V area near mouth or nose
• pain triggered by touch, drinking, washing face

• disorder of facial nerve causes paralysis of facial muscles on one side
• leads to loss of facial expression
• may appear abruptly w/ full recovery w/n 3-5 weeks

1. increased intraorbital pressure causes orbital bones to break at their weakest point
2. compression of orbital rim causes direct buckling of orbital floor

• periorbital edema ("puffy eyes")
• ecchymosis (distortion of skin color due to bleeding)
• local tenderness
• double vision
• restricted eye movements
• hypesthesia (lack of sensation) of cheek & upper lip (if infraorbital nerve damaged)
• Enophthalmos or proptosis (recession or protrusion of eye due to severe orbital edema or retrobulbar hemorrhage)

• restriction due to entrapment of an eye muscle, orbital edema, or damage to CN III
• to determine the cause, a forced duction test can be used

• advise patient not to blow nose
• use of nasal decongestant
• propylactic antibiotics to prevent orbital cellulitis
• use of steroids to decrease orbital edema

• diplopia present 10-14 days after trauma
• enophthalmos > 2mm 14 days after trauma
• cosmetically unacceptable to patient
• fractures involving 1/2 or more of orbital floor

• active infection of orbital soft tissue posterior to orbital septum
• in patients w/ underlying sinus disease, orbital fractures can result in this
• 90% of cases secondary to acute or chronic bacterial sinusitis

• cellulitis of face or eyelid
• dacryocystitis (inflammation of lacrimal/tear sac)
• dental infection
• intracranial infection
• postsurgical
• trauma
• bacteremia - infection in blood
• endophthalmitis - infection of soft tissues of eye

• fever
• proptosis
• chemosis - edema of mucous membrane & eyelid 
• erythema - skin irritation/reddening
• restriction of eye movement
• pain w/ eye movement

• involvement of orbital apex (demands aggressive management)
• delay could progress infection & development of apex syndrome
• also cause cavernous sinus thrombosis, blindness, CN palsies, & death

• with IV antibiotics
• may still progress to abscess formation (swollen area, usually filled w/ pus) leading to proptosis
• require surgical drainage

• edema, erythema, & inflammation of eyelids
• normal visual acuity, ocular motility, & pupil rxn
• no pain w/ eye movement
• no chemosis

• most common cause is sinusitis
• used to be Haemophilus influenzae before HIB vaccine
• hospitalization & IV antibiotics may be needed

• caused by superficial source like infected cyst or trauma
• usually treated with oral antibiotics
• may progress to localized abscess where surgical drainage required

• often follows internal hordeolum
• can become large/heavy enough to press on cornea causing visual distortions
• should be treated w/ month of hot compresses & lid massage
• if still not better, incised, curretted, & steroids

• painful, hot, swollen, red, eyelid bump
• hot compresses, lid massage, topical antibiotic

• acute infection (usually staphlococcal) of gland of Zeis or Moll
• may center around eyelash follicle which can be plucked to drain
• treatment: hot compresses & topical antibiotics

• oculomotor nerve does not work
• eye would not be able to look up, down, or inward
• since CN III doesn't innervate SO & LR, eye could position down & out
• patient would complain of diplopia

• CN III innervates levator palpebral superioris; so lack of innervation would cause ptosis
• also innervates sphincter pupillae & ciliary muscle; w/o innervation there is unopposed action of dilator & no ability to accommodate

• Diabetes (external ophth.)
• aneurysm
• tumor
• trauma
• inflammation
• vascular disease