Lateral orbital tubercle insertions (Whitnall’s tubercle?)
1)
check ligaments of LR
2)
lateral horn aponeurosis of levator
3)
orbital septum
4)
lateral canthal tendon
5)
Lockwood’s ligament
(Whitnall’s
ligament inserts at trochlea and between lacr. gland lobes)
Lockwood’s
ligament: connects IO capsule to IR capsule and to lower lid retractors
Whitnall’s ligament: where levator aponeurosis originates?
Walls of orbit
Medial (4): ethmoidal, lacrimal, maxilla, sphenoid
Floor
(3): maxilla, zygoma, palatine
Lateral
(2): zygoma, greater wing of sphenoid,
Roof
(2): frontal, lesser wing of sphenoid
- NB:
sphenoid everywhere except floor
MOST/LEASTS
Sclera:
-
thinnest at EOM insertions
-
thickest:posteriorly
Goblet
cells:
-
most at plica and caruncle
-
absent at limbus
Embryonic Derivatives
A)
ectoderm
1)
lid skin epithelium and appendages
2)
conj epithelium
3)
lens
4)
lacrimal gland
5)
lacrimal drainage (puncta, canal., sac, NLD)
6)
primary vitreous
B)
neuroectoderm
1)
neurosensory retina
2)
RPE
3)
ciliary epith. (both layers)
4)
iris sphinter and dilator
5)
optic nerve
C)
mesoderm
1)
endoth. of all blood vessels
2)
EOM’s
3)
temporal sclera
D)
neural crest: THE REST
A) Orbit
1)
orbit c.t.
2)
orbital bones
3)
trochlea
4)
meningeal sheath of O.N.
5)
ciliary nerve Schwann cells
6)
EOM tendons
B) Globe
1)
sclera
2)
cornea stroma and endoth.
3)
choroid
4)
c.b. muscle
5)
t.m.
6)
iris stroma
7)
melanocytes
8)
2nd and 3rd vitreous
Development dates:
Lens
(Day 25-40 or Week 4-6)
Day:
25:
optic vesicle
27:
lens plate
29:
lens pit (after 4 weeks)
33:
lens vesicle
35:
primary lens fibers (after 5 weeks)
40:
lens is obliterated (after 6 weeks)
40-240:
secondary lens fibers
56: Y
sutures (2 months)
9
month: pupil mb disappears
Glaucoma
8
month: angle formed
Nerve
at
birth: myelination to lamina cribosa (AAO)
7
month to 2 years after birth (Wright) - full
myelinization?
Retina
5
weeks: retinal pigment
8
months: nasal retinal vascularization
at
birth: temporal retinal vascularization
4
months post-natal: macula
Hyaloid fissure
week
5: hyaloid artery enters fissure –when lens
develops
week
6-8: closure (Moore )
month
8: regression
Comparisons
Structure New born Adult
globe
length 16 24
cornea
diam. 9.5-10 11
Sinus formation
1)
maxillary: birth (jaw)
2)
ethmoid: birth (nose)
3)
frontal: 6 years (forehead)
4)
sphenoid: slowly; complete around early puberty (brain)
A) Ciliary
ganglion
A) Roots
1) V1
sensory root is the long ciliary nerve; branch of nasociliary nerve
2)
parasympathetic root is from the inferior division of CN 3
3)
sympathetic root is from internal carotd
B) Branches
1)
short ciliary nerves; contain:
a)
parasympathetic innervation to iris and c.b.
b)
sympathetic innervation to iris and c.b., vessels
c)
sensory innervation of globe (iris, cornea)
Numbers
A) Retina
1)
1.2 million axons
2) 6
million cones
3)
120 million rods
4) 5
million RPE cells
B) Arteries
and nerves
1)
6-10 short ciliary nerves
2) 2
long ciliary nerves (sensory from NC n.) - sensory innervation to anterior eye
3) 20
short post. cil. arteries
4) 2
long posterior ciliary arteries
5) 7
anterior ciliary arteries (LR has one)
6)
intraorbital optic nerve: 25 mm (1 inch)
7)
intracranial optic nerve: 10 mm (1 cm)
C) Lens
1)
lens: 9.5 mm at equator
2)
bag after extraction: 10.5 mm
3)
sulcus: 11.5 mm
4)
zonules insert 1.5 mm from equ. ant surface
5)
zonules insert 1.25 mm from equ. Post surface
Attachments of uvea
1)
optic nerve
2)
scleral spur
3)
vortex veins
Attachments of vitreous
1)
optic nerve
2)
vitreous base
3)
macula
4)
retinal vessels
Attachments of Tenon’s
1) 3
mm posterior to limbus
2)
around optic nerve
Vortex veins
1) in
eye: ampulla are seen at equator (where they exit the choroid)
2) on
sclera: seen near nasal and temporal margins of IR and SR muscles
3)
have an oblique course within the sclera
Structures in vertical saccades
A) Origin
1) frontal
cortex
2)
superior colliculus
B) Secretaries
(Neil Miller) - premotor regions
1)
riMLF - rostral internucleus of the MLF(midbrain) - just posterior to the red
nucleus
2)
interstitial nucleus of Cajal
Structures in horizontal saccades
A) Origin
1)
frontal cortex: contralateral
2) superior
colliculus
B) Secretaries
(Neil Miller) - premotor regions
1)
PPRF: ipsilateral gaze
2)
MLF: contralateral gaze
Structures in vertical and horizontal pursuit
A) Origin
1) Occipital
cortex
B) Middle
men
2)
visual association areas (MT, MST)
3)
parietal cortex: ipsilateral
C) Secretaries
1)
pontine nuclei
2)
cerebellum
3)
vestibular nuclei
Supranuclear Anatomy (Basic)
A) Origin
1)
frontal lobe: contralateral saccades
2)
parietal lobe: ipsilateral pursuit
B) Secretaries
1)
PPRF: ipsilateral gaze
2)
MLF: contralateral gaze (as soon as it leaves PPRF, it crosses)
Clivus:
bone from from foramen magnum until dorsum sella; includes sphenoid and
occipital bone
Blood Supply
A) Globe
1)
optic nerve head: cenral retinal artery
2)
prelaminar region: posterior ciliary arteries
3)
lamina cribosa: posterior ciliary arteries
4)
post-laminar region: pial branches of CRA
B) Behind
globe
1)
orbital optic nerve: ophthalmic artery
2)
intracanalicular optic nerve: ophthalmic artery
3)
intracranial optic nerve: ICA, ACA, ant. comm. artery
4)
chiasm: ICA, anterior comm. art.
5)
optic tract: anterior choroidal artery
6)
LGN: anterior and posterior choroidal art.
7)
optic radiations MCA and PCA
8)
occipital cortex: MCA and PCA
ICA/ECA arterial anastomosis
1)
the 2 intracavernous ICA’s are in communication with the meningeal arterial
system
arising from the 2 ECA’s
i)
ascending pharyngeal artery
ii)
internal maxillary artery
2)
lacrimal artery anastomoses with branches of the external carotid system at 2
or (sometimes) 3 sites
i) middle
meningeal artery
ii)
anterior deep temporal artery
iii)
infraorbital artery (sometimes)
Iris stroma
1)
melanocytes
2)
clump cells
3)
chromatophores
Le
forte Fracture which involves floor: 2 and 3
Drusen
<64:
small
65-125:
medium
>125 large
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