Please enable JavaScript.
Coggle requires JavaScript to display documents.
Orbit and Nasal Cavity (Week3) (Visual Field Defects (Monocular Blindness …
Orbit and Nasal Cavity (Week3)
Components
Eye
Outer
Sclera
Cornea
Middle
(Vascular)
Choroid
CIliary Body
Lens (Suspensory ligaments)
Inner
(Nervous)
Retina
Extra-occular
Medial Rectus
Superior Oblique (CN4)
Lateral Rectus (CN6)
Inferior Oblique
Inferior Rectus
Superior Rectus
IO
LR
SO
SR
MR
IR
Inferior
always
Extort
Superior
always
Intort
Intra-occular
Iris Radial / Dilator muscles
Sympathetic
Superior Cervical Ganglion (C2/3) > Postgang Sympathetic Nerves > follow ICA > Cavernous Sinus, Optic Canal / Superior Orbital Fissure
Iris Circular / Constrictor muscles
Parasympathetic
CN3 > Cillary Ganglion > Short Cillary Nerve
Cillary muscles
- Both Para & Sym
Superior Cervical Ganglion & CN5
CN3 > Cillary Ganglion > Short Cillary Nerve
Nerves
Cranial Nerves 2, 3, 4, 6
Occulomotor Never (CN3)
Viscero Motor (Parasym)
: Iris Circular/Constrictor + Cillary
Edinger Westphal Nucleus
Cillary Ganglion
Somatic Motor
: IO / MR / SR / IR +
LPS
Brainstem (
Midbrain
) > Posterior Cranial Fossa, Middle Cranial Fossa, Cavernous Sinus
Superior Orbital Fissure
Effects of Lesion:
LPS: Ptosis, drooping of upper eye lid
(Parasympathetic) Pupil dilation, Sympathetic dominate
(MR) Unopposed LR, eye lateral deviation
Diplopia all except lateral gaze
Trochlear Nerve (CN4)
Superior Oblique
Brainstem (
Midbrain
) > Posterior Cranial Fossa, Middle Cranial Fossa, Cavernous Sinus
Superior Orbital Fissure
Effects of Lesion:
Paralysis of SO4.
Elevation during forward gaze
Elevation increase with Adduction
Elevation decreases with Abduction
Abducent Nerve (CN6)
Lateral Rectus
Brainstem (
Pontomedullary
) > Posterior Cranial Fossa, Middle Cranial Fossa, Cavernous Sinus
Superior Orbital Fissure
Effects of Lesion
:
Paralysis of LR6.
Adduction at rest / Cannot abduct
Diplopia
on
lateral gaze
of affected eye
Optic Nerve (CN2)
Lateral Geniculate Nucleus
Axon of
Retinal Ganglion Cells
Glial cells
Covered by 3 meningeal layers
Nerve
Chiasm
Tract
Lateral Geniculate Nucleus
Radiation
Thalamus
Visual Cortex
Chiasm
Tract
Radiation
Thalamus
Superior Cervical Ganglion (C2/3)
> Internal Carotid Plexus > Separate in Cavernous Sinus, Optic Canal / Superior Orbital Fissure, merge with Long & Short Cillary (which is a root of Cillary Ganglion)
Iris Radial/Dilator
Cillary Ganglion
Viscero-motor Parasympathetic (CN3) from Edinger Westphal Nucleus
Viscero-motor Sympathetic from Superior Cervical Ganglion
Somatic-sensory (Eyeball) from trigeminal
Phototransduction
:
Light stimulus onto
Photoreceptors
Image is inverted & reversed
Nasal retina more extensive
Light transduced into A.P
Bipolar cells
transmit A.P
Retinal ganglion cell axons
(aka.
Optic Nerve
)
(Like 1st + 2nd Order GSA)
Optic Chiasm
Hemi-decussation
Only Nasal decussates
Optic Tract
Branches off for reflexes (Extra-Occular)
Thalamus
/
Lateral Geniculate Nucleus
(Like 3rd Order GSA)
Optic Radiation
1o/2o
Visual Cortex
VC1 at calcarine sulcus
Ventral Visual Pathway
What
Dorsal Visual Pathway
Where / How
Visual Field Defects
Monocular Blindness
Laceration of Optic Nerve / Axon of Retinal Ganglion
Bitemporal Hemianopia
Laceration at Optic Chiasma
Binasal Hemianopia
COMPLEX
Homonymous Hemianopia
Laceration at Optic Tract
Nasal Cavity
Air Sinuses
Sphenoid Sinus
Sphenoethmoidal Recess
Innervated by Opthalmic Division
Ethmoid Sinus
Middle Nasal Concha
Maxillary Sinus
Middle Nasal Concha
Frontal Sinus
Middle Nasal Concha
General Layout
Inferior Concha
Nasolacrimal Duct
Middle Concha
Hiatus Semilunaris
Frontal Sinus
Maxillary Sinus
Ethmoidal Sinus
Ethmoidal Bulla
Above Hiatus Semilunaris
Contains cells
Superior Concha
Sphenoethmoidal Recess
Posterior & Superior to Superior Concha
Pharyngeal Recess
Behind Tubal Elevation
Inferior and Posterior to Sphenoethmoidal Recess
Common site for NPC
Applications
Visual Reflexes
Light
Pupillary light reflex
Near Objects
Accomodation / Convergence
Pain / Emotional State
Pupil dilation
Eye Movements
(Con/Di)Vergence
Disonjugate
Focus of object moving near or far)
Saccades
Conjugate (Rotate at the same time/direction/amount)
Quick Darting
Smooth Pursuit
Conjugate
Slow tracking
Others
Optokinetic Reflex
Combine Saccade & Smooth Pursuit
Vestibulo-Ocular Reflex (VOR)
Maintain foveation despite head movements
Coordinated by reflex arc
Thought Expansion: Superior Cervical Ganglion Lesion (Horner's Syndrome)
Sympathetic
Smooth / Cardiac / Glands
Ptosis
Pulpil Constrict (Iris Radial/Dilators not working)
Blood vessels (Red face, Increase temperature)
Sweat Glands
