Anatomy Flashcards
Percentage of population that have a cilioretinal artery supplying the eye
20%
What is the effect of the cilioretinal artery
allows blood supply of the eye when there is a CRAO
Location of eye the cilioretinal artery
between macula and OD from a posterior ciliary artery source
What does the cilioretinal artery supply
foveal photoreceptors
what percentage of people have the ophthalmic BELOW the optic nerve?
15%
what percentage of people have the ophthalmic medially ABOVE the optic nerve?
85%
What form the circle of Zinn
where the short ciliary nerves penetrate the globe around ON to form the arterial circle of Zinn.
Short ciliary nerve supplies ?
The Optic Head nerve and the choroid up to the equator
What is the thinnest Cranial nerve ?
Trochlear nerve
Trochlear nerve exits the skull ?
SOF
SOF is located ?
between the greater and lesser wing of the sphenoid
Trigeminal V2 nerve exits the skull ?
Forman rotundum
Trigeminal V3 nerve exits the skull ?
Foramen ovale
Contents of the foramen ovale?
O- Optic ganglion
V - V3 of the trigmenial nerve
A - Accessory meningeal
L- lesser petrosal
E - Emissary vein
Branches of the Ophthalmic division V1
Frontal
Lacrimal
Nasociliary
Blood supply of the optic nerve ?
Intraocular: short ciliary artery
Intracranial: pial vessels of the short ciliary
IOF is located
lies between greater wing of sphenoid and maxilla
Medial wall of the orbital ?
SMEL
The medial orbital wall comprises four bones (anterior to
posterior):
● the frontal process of the maxilla
● lacrimal
● ethmoid
● lesser wing of sphenoid.
Floor of the orbital ?
MY ZIPPED PANTS are on the floor
- orbital plate of maxillary bone
- small orbital process of palatine bone
- orbital surface of zygomatic bone.
Lateral wall of the orbital ?
Zara is a great wing woman
Zygomatic
Greater wing of sphenoid
Roof of the orbital ?
FRONT - LESS
● the orbital plate of the frontal bone
● the lesser wing of sphenoid bone (posterioly).
Foramen that the internal carotid enters the Skull ?
Foramen Lacerum
Veins that drain INTO the cavernous sinus ?
Superior and inferior orbital veins
Veins that drain OUT of the cavernous sinus
- Superior and inferior petrosal –> internal jugular
- Emissary vein –> Pytergoid plexus
Inferior optic radiations are responsible for what Visual Field
Meyers loop
Superior visual field - pass through the temporal bone and terminate the visual cortex inferior to the calcarine sulcus
Borders of the cavernous sinus ?
Anterior - pituarity gland
Posterior - apex of petrosal part of the temporal bone
Medially - pituraity fossa
Roof - Pituarity gland
Floor - sphenoid
Superior optic radiations
Inferior visual field - pass through the Parietal bone and terminate the visual cortex superior to the calcarine sulcus
Visual cortex area responsible is at the cortex level
17
optic nerve fibre layers of the retina that are responsible for the temporal retina ?
ipsilateral 2,3,5 -
T for Temporal, T- for team 5 a side
optic nerve fibre layers of the retina that are responsible for the nasal retina ?
contralateral 1,4,6
Lesion anterior to the Willebrand’s Knee?
Superior quandrantopia in the contralateral eye and ipsilateral junctional scotoma
Lesion at the retina ?
Scotoma of the ipsilateral eye
Lesion at the lateral chiasm?
Ipsilateral hemianopia
Lesion at the visual cortex - occlusion at the calcarine artery po the posterior cerebral artery
bilateral homonymous hemianopia with macular sparring
EOM which is the shortest to longest ?
MR 5.5
IR 6.5
LR 6.9
SR 7.5
EOM tendon length shortest to longest ?
MR
IR
SR
LR
Day 26 the which EOM develop?
SR, MR, IR and IO
Day 27 which EOM develop?
LR
Day 28 which EOM develops ?
SO
Each rectus muscle receives blood supply from 2 ciliary arteries except?
Lateral rectus
First nerve to suffer compression in the cavernous sinus ?
6th cranial nerve
Circle of zinn is incomplete in what percentage of people ?
23%
Nasociliary artery branches into the
Ethomidal anterior
Ethmoidal posterior
Infratrochlear
Longest unprotected nerve ?
Trochlear
Only nerve to exit the brainstem dorsally ?
Trochlear
Smallest cranial nerve in terms of axons?
Trochlear
Orientation of the lateral rectus to the IC in the cavernous sinus ?
Lateral
Oculomotor functions ?
Motor - somatic and visceral
Sensory
Somatic -
Contralateral innervation of SR
Ipsilateral of IO, IR, MR
Visceral - pupillary light reflex
bilateral levator superioris
Snesory
What nerve fibres pass anteriorly in the optic chiasm ?
inferonasal
The Roof of the posterior fossa
.
Tentorium cerebelli
The contents of the posterior fossa
Cerebellum
Pons
Medulla oblongota
Anterior border of the posterior fossa
Superior border of petrous temporal bone and dorsum sellae
The cerebellum lies in the cerebellar fossa, in the squamous part of occipital bone.
Cornea endothelium: Thickness, organisation of layers, amount of cells, function
- Thickness 4-6um
- It is a monolayer of interdigitating hexagonal cells joined by tight junctions
- At birth: 1 million cells with approximately 3800 endothelial cells/mm2; these cells are loss with ageing. Cornea endothelium do not regenerate but rather stretch to fill gaps left by cell loss
- Function of the cornea endothelium is to keep cornea dehydrated and clear. If cell count < 500cells/mm2, pump action will be insufficient and this could lead to corneal oedema
Schwalbe’s line
Schwalbe’s line is the termination of the Descemet’s membrane and delineates the outer limit of the cornea endothelium -it is a structure that can be seen usually only on gonioscopy
Posterior embryotoxon
Posterior embryotoxon is the thickening and anterior displacement of the Schwalbe’s line
The lacrimal sac measures
12-15mm
The nasolacrimal duct measures
12-18
Location of the Hasner valver?
At inferior meatus - congenital lacrimation irritation
Length of the vertical part of caniculi
2mm
Location of Rosenmuller valve?
Mucosal tissue fold, prevents reflux into the nasolacrimal sac
length of the horizontal part of caniculi
10mm
A critical gene in the development of surface ectoderm?
PAX6 is a critical gene in the development of surface ectoderm.
Lipid layer diameter
0.1 um
Mucin layer diameter
0.2-0..5um
Layers 1, 2 of the lateral geniculate represent what pathway and what are they useful for ?
represent magnocellular pathway, concerned with detection of movement
Layers 3-6 of the lateral geniculate represent what pathway and what are they useful for
represent parvocellular pathway, concerned with colour vision and visual acuity
Sherrington’s law
Sherrington’s law of reciprocal innervation states that the contraction of an extraocular muscle occurs together with the relaxation of the ipsilateral antagonist muscle.
Hering’s law
Hering’s law of equal innervation states that there are equal contractions of the contralateral ( in the fellow eye) yoke muscles.
The nuclei of the Trigeminal nerve are located ?
Main sensory
sensory
Mesencephalic
Motor
The nuclei of the Oculomotor nerve located?
In the superior colliculus of the midbrain and runs between the poster cerebral artery and superior cerebellar artery to the cavernous sinus.
The nuclei of the Trochlear nerve located?
In the inferior colliculus, in the anterior part of the grey matter surrounding the midbrain
The nuclei of the abducens nerve located?
At the pontomedullary junction, lies in the subarachnoid space, crosses over the petrosal part of the temporal bone through an osteofibrous canal called Dorello’s canal. It runs in the cavernous sinus lateral to the internal carotid
Relationship between the trochlear and oculomotor nerve?
Enters the cavernous sinus inferior posterior to the oculomotor nerve and exits the sinus above the oculomotor nerve
Trochlear innervates the superior oblique / contralaterally or ipsilaterally
Contralaterally
What blood vessels supplies the prefrontal cortex?
The anterior cerebral artery (ACA) supplies the premotor frontal cortex which initiates saccades
Where are the FEF located ?
visual cortex 8
Supranuclear pathway
Supranuclear Eye Movements
These are movements controlled by higher centers in the brain (above the nuclei of the cranial nerves), particularly in areas such as the cerebral cortex, brainstem, and cerebellum. These centers generate signals that descend and modulate the activity of the cranial nerve nuclei responsible for eye movements.
Supranuclear pathways include areas like the frontal eye fields (FEF), which are involved in voluntary saccadic (quick) eye movements, and the parietal eye fields for visual attention.
The PPRF (paramedian pontine reticular formation) and MLF (medial longitudinal fasciculus) help coordinate movements like horizontal and vertical gaze.
Disruption in these areas leads to problems such as gaze palsies, nystagmus, or saccadic initiation failure (difficulty starting voluntary eye movements).
Examples of supranuclear movements:
Saccades: Quick, voluntary shifts of the eyes from one target to another (controlled by the cortex).
Smooth pursuit: Slow, continuous tracking of a moving object.
Vestibulo-ocular reflex (VOR): Compensatory eye movements during head motion to stabilize gaze (this has both supra- and infranuclear involvement).
Role of the basal ganglia
The basal ganglia has a number of functions:
Suppresses unnecessary reflexive saccades
Controls voluntary saccades
Dolls head manoeuvre?
Doll’s Head Maneuver (Oculocephalic Reflex)
The doll’s head maneuver is used to test the integrity of the vestibulo-ocular reflex (VOR), which is a key supranuclear reflex. It involves turning the head to one side while observing the eyes’ ability to remain fixed on a stationary target.
Normal response: When the head is turned to one side, the eyes move in the opposite direction to maintain fixation (compensatory movement).
This reflex indicates that the brainstem (supranuclear pathway) is intact and working properly.
Abnormal response: If the eyes do not move (i.e., they move with the head instead of in the opposite direction), it suggests damage to the brainstem, vestibular system, or higher centers responsible for the VOR.
This test is especially useful in unconscious or comatose patients to assess brainstem function, as they cannot voluntarily move their eyes.Relies of the vestibular-ochlear pathway - eyes move with passive movement of the head. This means that the infranuclear pathway is intact and the problem must be supranuclear
Blood supply of the lateral rectus ?
Lacrimal artery
Where does the IO orginate
inferior oblique muscle of the eye originates from the maxillary part of the floor of the orbit. It arises anteriorly from the orbital floor, lateral to the nasolacrimal fossa.
Where does the SO orginate
the periosteum of the sphenoid bone above and medial to the optic canal, inserts into sclera posteriorly and superiorly under the superior rectus behind the equator
isolate the SO at how many degrees ?
54 degrees adduction
Isolate the recti at
23 abduction
Rectus muscle wit the largest arc is
Lateral Rectus with 12 mm
EOM with Smallest to largest tendon length?
So, the order from smallest to largest tendon length is:
Inferior Oblique (IO): 1-2 mm
Medial Rectus (MR): 3.7 mm
Inferior Rectus (IR): 5.5 mm
Superior Rectus (SR): 5.8 mm
Lateral Rectus (LR): 8.8 mm
Superior Oblique (SO): 19 mm
Thinnest EOM ?
Is the LR at 9.2mm
Smallest to largest distance from limbus ?
MR (5.5) – IR (6.5) – LR (6.9) – SR (7.7)
isolate the IO at how many degrees ?
51 degress adduction
Primary role of the following:
Superior’s
Inferior’s
Recti
Oblique’s
superiors - intort
Inferior - extort
Recti - adduct
Obliques - abduct
at its origin what position is the ophthalmic artery to optic nerve
As it lies inferolateral to optic nerve
The overall precentral corneal tear film thickness is probably around
4-5um
Distance from Ora Serrata to the Schwalbe line?
Distance from Schwalbe line:
5.75mm nasally; 6.50mm temporally
This distance is greater in myopia compared to hypertropia
diameter of eye 20mm circumference 63mm at ora serrata compared to 24mm and 75mm respectively at the equator
what are the 4 remnants of the hyaloid artery?
1) Mittendorf’s Dot
Glial remnant posterior to the lens
2) Bergmeister’s papilla
Glial remnant anterior the optic disc
3) Persistent hyaloid artery
Vascular remnant from the optic disc
4) Persistent fetal vasculature
Vascular remnant and retrolental mass
Mittendorf dot ? My pretty lady
glial remnant posterior to the lens
Bergemister Papilla
glial remanent anterior to the optic disc
Persistent hyaloid artery
vascular remanent from the optic disc
Persistent fetal vasculature
Vascular remanent and retrolental mass
Where does the medial canthal ligment lie in relation to the nasolacrimal duct ?
The medial canthal tendon/medial palpebral ligament are anterior to lacrimal sac.
Where is the angular vein in relation to the medial canthys
The angular vein is 8mm medial to medial canthus.
The relationship between the ethmoidal sinus and lacrimal sac ?
The ethmoidal sinus is medial to the lacrimal sac.
Which of the following muscle inserts most posterior to the limbus?
Superior Oblique
Which of the following is the rough size of the lacrimal gland?
20mm long and 12 mm wide
Which EOM muscles will lead to pain in optic neuritis
The superior rectus, medial rectus share a connective tissue sheath with the optic nerve
hence pain with retrobulbar optic neuritis
Long ciliary nerve and short ciliary nerve
The long ciliary nerve, which passes through the choroid and transmits sensory fibres to the cornea, iris and ciliary body (as well as sympathetic fibres to the dilator pupillae muscle) is a branch of the nasociliary nerve, itself a branch of the ophthalmic nerve. The short ciliary nerve arises from the ciliary ganglion and carries sensory (from the nasociliary), sympathetic and parasympathetic fibres.
The anterior portion of the optic radiation is supplied by:
anterior choroidal artery
posterior cerebral
posteror choroidal artery
lateral striate artery
Anterior choroidal artery
Giant cell arteritis affects what arteries?
can affect the cerebral arteries, the ophthalmic artery and the central retinal artery but it will not affect retinal arterioles because they do not possess an elastic layer.
The facial nerve splits into what 5 branches?
Within the parotid gland, the nerve terminates by splitting into five branches:
Temporal branch
Zygomatic branch
Buccal branch
Marginal mandibular branch
Cervical branch
two nerves that enter the parotid gland?
1 splits int o5 branches
the other innervates
Glossopharygeal innervates
Facial nerve: splits into 5 branches:
Temporal branch
Zygomatic branch
Buccal branch
Marginal mandibular branch
Cervical branch
The facial nerve exits the skull via the
The facial nerve then exits the facial canal (and the cranium) via the stylomastoid foramen. This is an exit located just posterior to the styloid process of the temporal bone.
Location of the Edinger Westphal?
Midbrain (dorsal) posterior to the oculomotor
Oculomotor relationship between Edinger and MLF?
In the middle
Edinger in the back
ML in the front
Blood supply of the optic chiasm and optic tracts
Small branches of the anterior cerebral artery and the superior hypophyseal artery supply the chiasm and intracranial portion of the optic nerves whereas the optic tracts are supplied by small branches of the anterior choroidal and posterior communicating arteries.
Sympathetic innervation of the eye?
Posterior hypothalamus –> centre of bulge c8-t1–> traverses over the lung apex to the superior cervical ganglion where the carotid bifurcate at t4 and then moves with the ICA to the cavernous sinus with long ciliary nerve which a branch of nasociliary from the Trigeminal V1 to the the dilator radial muscle
Where does the levator palpebrae superior originate and insert into ?
It originates with a short and narrow tendon from the inferior aspect of the lesser wing of sphenoid bone, superior and anterior to the common tendinous ring. The muscle belly gradually widens as it courses anteriorly toward the eyelid. The muscle fibers penetrate the upper eyelid, inserting to its parts via two aponeurotic fascicles;
Deep fibers attach to the anterior surface of the superior tarsus
Superficial fibers radiate through the eyelid and orbicularis oculi to finally attach to the skin of the superior eyelid.
Parasympathetic innervation of the eye
Afferent pupillary fibers start at the retinal ganglion cell layer and then travel through the optic nerve, optic chiasm, and optic tract, join the brachium of the superior colliculus, and travel to the pretectal area of the midbrain, which sends fibers bilaterally to the efferent Edinger-Westphal nuclei of the oculomotor complex –> ciliary ganglion –> short ciliary nerve branch of nasociliary of the V1 –> pupillary constriction
Blood supply of the levator palpebrae superioris ?
Levator palpebrae superioris receives arterial blood supply from the internal carotid artery, via ophthalmic artery and its supraorbital branch.
Tarsal Muscle (muller muscle)
Superior tarsal is a smooth muscle of the upper eyelid. It originates from the deep surface of levator palpebrae superioris and inserts inferiorly, to the superior tarsal plate of the upper eyelid.
Reflex afferent and efferent
Pupillary
Accommodation
Corneal
Lacrimation
Jaw jerk
Auditory
GAG
Light
Pupillary 2,3
Accommodation 2,3
Corneal V1, Bilateral V2
Lacrimation V1, V2
Jaw jerk V3,V3
Auditory 8,7
GAG 9,10
Light 2,7
Grey line:
Anterior
Posterior
Ant; eyelash, cilia, glans of moll, orbicularis muscle.
Post: meibomian gland opening
Cells in the lacrimal gland
Ductal; columnar epithelium with central lumen and myoepithelial cells.
Acinar cells constitute 80% of the lacrimal gland, contributing to the primary secretory apparatus.
Spread of following cancer
SCC
Retinoblastoma
SCC - lymph
Retinoblastoma; haematogenous
Parasympathetic innervation of the lacrimal gland
Parasympathetic:
Preganglionic fibres are carried in the greater petrosal nerve (branch of the facial nerve) and then the nerve of pterygoid canal, before synapsing at the pterygopalatine ganglion.
Postganglionic fibres travel with the maxillary nerve, and finally the zygomatic nerve.
Stimulates fluid secretion from the lacrimal gland
Sympathetic innervation of the lacrimal
Sympathetic
Fibres originate from the superior cervical ganglion, and are carried by the internal carotid plexus and deep petrosal nerve.
They join with the parasympathetic fibres in the nerve of pterygoid canal, and follow the same route to supply the gland.
Inhibits fluid secretion from the lacrimal gland
Relation between common tendon ring and levator palpebrae superioris?
Levator Palpebrae superior oirginates from the lesser wing of sphenoid ant and superioly from the ring
Why does the SR and MR with optic neuritis
The superior rectus, medial rectus share a connective tissue sheath with the optic nerve
hence pain with retrobulbar optic neuritis
EOM closest to the limbus ?
MR (5.5)
Bones of the medial wall - Ant to posterior
The medial wall of the orbit is thin and is formed anterior-posterior by the maxilla, lacrimal, ethmoid
Which of the following about the trochlear nerve is true?
a.The trochlear nerve is the only cranial nerve to emerge from the ventral aspect of the midbrain
b.The trochlear nerve supplies the inferior oblique muscle
Its nucleus lies in the posterior periaqueducal grey matter at the level of the inferior colliculus
c.It decussates before leaving the brainstem
d.It has the shortest intracranial course of all cranial nerves
The trochlear nerve supplies the inferior oblique muscle
Its nucleus lies in the posterior periaqueducal grey matter at the level of the inferior colliculus
Right optic tract syndrome produce
Bowtie atrophy of the left optic nerve
Left RAPD
Left homonymous hemianopia
Temporal Pallor of the right optic nerve
Cells shape and thickness in the cornea endothelium ?
- Thickness 4-6um
- It is a monolayer of interdigitating hexagonal cells joined by tight junction
innervation of the orbicularis muscle - upper and lower
The innervation of orbicularis is from CN VII ( temporal branch supply upper half, zygomatic or buccal branch innervates lower half)
The sphenoid sinus drains into the sphenoethmoidal recess which lies where?
Above superior turbinate
Above middle superior turbinate
Above inferior turbinate
Inferior meatus
Middle meatus
Above superior turbinate
Where does the lateral and medial horn of the palpebral ligament insert ?
Lateral horn forms the lateral palpebral ligament which then inserts into lateral orbital tubercles
The medial horn forms the medial palpebral ligament which then inserts into frontolacrimal suture
Describe retrochiasmal lesions
Retrochiasmal lesions produce contralateral homonymous hemianopia
The more congruent the field defect, the more posterior the lesion
Congruency refers to visual defect which are identical in each eye
Optic canal borders and location
1) The optic canal is located in the sphenoid
2) It passes anteriorly, inferiorly and laterally from middle cranial fossa to apex of the orbit
3) It is formed by the two roots of the lesser wing of sphenoid
4) They are found 25mm apart posteriorly, 30mm apart anteriorly
5) They are narrowest anteriorly.
6) The medial relations include the sphenoidal and posterior ethmoidal air sinuses
7) The superior relation is the olfactory tract.
At how many weeks do the neural crest cells from the cornea start forming the chamber angle?
week 7
Embryonic clossure is when ?
Week 6
What ventricle is the optic chaism ?
What ventricle is the abducens?
3rd ventricle
4t ventricle
5 layer of the bruchs memberane
Bruch’s membrane is the innermost choroidal layer, it is itself a 5 layered structure ( from outer to inner):
Basement membrane of choriocapillaries
Outer collagenous zone
Elastic layer
Inner collagenous zone
Basement membrane of the RPE
5 layers of the choroid
Histology of choroid-5 primary layers from inner ( closer to retina) to outer (closer to sclera):
Bruch’s membrane
Choriocapillaries
2 vascular layers
Sattler’ (internal)
Haller (external)
Suprachoroidal layer
RPE
Information regarding the vitreous cavity
Capacity 5ml
Depth 16.6
Vitreous anatomy
Acellular
Avascular
2) Not a primary site of inflammation, but there can be overflow of inflammatory cells from inflammation of surrounding structures
3) Bacterial endophthalmitis:
Neutrophilic infiltration of vitreous and liquefaction
4) Non-infective uveitis:
Lymphocytic infiltration of the vitreous
What is the parvocellular pathway in the lateral geniculate nucleus responsible for?
Color vision and centeral vision
Occlusion of the LPCA can cause
Occlusion of LPCA, SPCA can cause:
Triangular syndrome of Amalric
Secondary to GCA, Lupus etc
Key measurements of the blind spot?
Key measurements:
17 degrees from the fovea
5-7 degrees in size
The fovea is 4mm away from the optic nerve head
The fovea is 0.8mm lower than the optic nerve head
where is the facial nuclei located ?
Pons
How many weeks/month does the eyelid adhesion breakdown?
5 months / 20 weeks
Collagen most common in corneal stroma ?
type I and V
The basement membrane of the outer ciliary epithelium is continuous with which structure?
The RPE
How does the ciliary process occur?
Fold in the optic cup
The framemork of the TM : anterior to posterior
2) Uveal meshwork:
The uveal meshwork is the most anterior portion of the trabecular meshwork and is located adjacent to the iris. It is composed of large diameter beams of collagen and contains pigmented cells called the trabecular cells.
3) Corneoscleral meshwork:
The corneoscleral meshwork is the middle portion of the trabecular meshwork and is located between the uveal meshwork and the scleral spur. It is composed of smaller diameter collagen beams and sheets and contains cells called the corneoscleral cells.
4) Juxtacanalicular meshwork:
The juxtacanalicular meshwork is the most posterior portion of the trabecular meshwork and is located adjacent to the Schlemm’s canal, which drains the aqueous humour from the eye. It is composed of a thin layer of cells and collagen fibers that surround the canal and is responsible for regulating the outflow resistance of the aqueous humour.
o diagnose Horner’s syndrome, what happens when apraclonidine 1% is instilled on the miotic pupil in a patient with Horner’s?
Dilates are 60mins
Which head posture would be adopted in a right superior oblique paresis?
Head tilt to left, face turn to left, and chin depression
Which structure is a monolayer of cuboidal cells?
Lens epithelium
What the choroid derived from
Choroid is the posterior part of the uvea:
Uvea develops from mesenchyme
This is in contrast to the retina and RPE which are derived from neural ectoderm
200um in overall thickness at birth, decrease to 80um by age 90
Which of the following isolates the depressor function of superior oblique?
51 degrees of adduction
Lacrimal gland cells are formed from what ?
Epithelial cells arising from the conjunctiva
4 layers of the ocular epidermis
4 layers of keratin producing layers -from superficial to deep
keratin layer aka stratum corneum/ horny layer-this layer is devoid of nuclei
granular layer aka stratum granulosum-contains keratohyline granules, one or two layers of cells
prickle cell layer aka stratum spinosum-polygonal cells with eosinophilic cytoplasm. Free border of cells joined by spiny desmosomes. Five cell layer thick
basal cell layer aka stratum basale-single row of cells, contain melanin derived from melanocytes
what weight does the human les weight and what does it increase by every year ?
90mg and increase by 2mg every year
Features of the lateral medually syndrome
Lateral medullary syndrome ( Wallenburg)-ipsilateral anhidrosis, ipsilateral pain/ temperature impairment on the face, contralateral loss of pain and temperature in limbs, dysarthria, dysphagia
At the medial end of the upper eyelid, what does the ophthalmic artery divide into?
Supratrochlear and dorsal nasal artery
When does the sclera begin to form?
Week 7
Where is the deep retinal vascular plexus?
Inner nuclear layer
First pharyngeal arch derivates
First pharyngeal arch give rise to:
Skeletal component-upper and lower jaw
Muscles of mastication
Second pharyngeal arch
Support the jaw, tongue, larynx
CN VII
The skeletal elements include the stapes, stylohyoid ligament and upper part of hyoid
The muscles of facial expression, stylohyoid, stapedius
Branches of the external carotid artery?
S: superior thyroid artery
A: ascending pharyngeal artery
L: lingual artery
F: facial artery
O: occipital artery
P: posterior auricular artery
M: maxillary artery
S: superficial temporal artery
Superifical retinal vascular plexus is located ?
Ganglion cell layer
Hyaloid artery begins to regress
4 month after conception
Tfollowing term describes which structure? Formed when stalk of cells connecting lens pit to surface ectoderm degenerates by apoptosis.
Lens vesicle
Pre corneal tear film
Lipid layer
Mucin layer
Pre corneal 5 micrometers
Lipid layer 0.1 um
Mucin Layer 0.02-0.05 um
RPE diameter at the macula and at that periphery ?
cell diameter 10-14um in macula, 60um in the periphery
Average depth of the vitreous cavity ?
Average volume in ml
16.5mm
5.5ml
Thickness of the tarsal plate?
1mm
Anterior chamber begins to appear in what month
3month
Schlemm canal formed how many months after conception?
4months
What is the relation of the optic canal to the sella turcica?
Anterior lateral
Average depth of the anterior chamber?
3.11
Where are most of the conjunctival goblet cells located ?
Inferior nasal quadrant
At what point does the optic nerve become myelinated ?
7 months
Hyaloid artery first develops?
Week 5
Ciliary epithelium is a crucial component of what barrier?
Blood aqueous barrier?
Structures that run through the IOF
Infraorbital nerve
Zygomatic nerve
Branch from pterygopalatine ganglion
Pterygoid venous plexus
(from medial to lateral) is: Inferior Orbit Gets Infra-Orbital Nerves and VeinZ.
At approximately how many weeks gestation does the apoptosis of vessels around the lens start?
9 weeks
Anatomical location ofthe Ciliary ganglion
. Anatomical relations
lies 1cm anterior to the annulus of Zinn
lateral to ophthalmic artery, between optic nerve and lateral rectus
Difference betweenthe short and long ciliary nerve?
.Short ciliary nerve
short ciliary nerves formed from:
Non synapsing sympathetic fibres
Sensory fibres
Postganglionic parasympathetic fibres
branches out from ciliary ganglion
The long ciliary nerve arise directly from nasociliary branch of V1
it only has a sensory component and doesn’t pass through the ciliary ganglion.
Long ciliary nerves supply the sensation to the cornea
What overlies the root of the middle turbinate?
Posterior lacrimal crest
Where are incompletely digested residual bodies typically deposited with age?
Between bruchs and RPE
How is the primitive pupillary membrane formed?
The primitive pupillary membrane is indeed formed by condensation of the mesenchyme and covers the anterior surface of the lens. It degenerates around the eight month and remnants can frequently be seen postnatally. Sphincter and dilator muscles of the risi are formed by the pigmented cells of the neuroectoderm. The neuroectoderm on the edge of the optic cups extends onto the posterior surface of the pupillary membrane to fuse and become the iris.
What gene is curical for the development of the ectoderm?
The surface ectoderm is derived from the ectoderm. PAX6 is a critical gene in the development of surface ectoderm
Where does the infraorbital nerve and artery travel?
Maxillary
Where does the SO muscle orginiate in relation to the Optic Canal
Superior medial
An inflammation of the lacrimal gland produces what disease
Dacroadentitis
Average volume of the anterior chamber in ul
220ul
At which month does the limbus start to appear after conception?
3months
Where does the superior oblique muscle insert into sclera/
Posterior and superiorly
Components of the inferior orbital fissure from medial to lateral
Inferior Orbit Gets Infra-Orbital Nerves and VeinZ
IO: inferior ophthalmic vein (tributary to both pterygoid venous plexus and cavernous sinus)
G: ganglionic branches from pterygopalatine ganglion to maxillary division of trigeminal nerve
ION: infra-orbital nerve (branch CN V2)
A: infra-orbital artery (branch maxillary artery)
V: infra-orbital vein (drains inferior orbit, communicates with inferior ophthalmic vein, tributary to pterygoid venous plexus)
Z: zygomatic nerve (branch CN V2)
Nerve affected:
Uncal herniation
Cavernous sinus thrombosis
PCA
AICA
Uncal herniation 3rd
Cavernous sinus thrombosis 6th
PCA 3rd
AICA 6th
Cicatricial entropion is caused by what?
Cicatricial entropion
Scarring of the tarsoconjunctiva causes inward rotation of the mucocutaneous junction
How is the superior vein subdivided and what does it drain into?
Superior ophthalmic vein can be divided into three parts
First passes along medial border of superior rectus muscle
Second passes posterior lateral under superior rectus, entering muscle cone
Third passes posteriorly along lateral border of superior rectus, enters superior orbital fissure, outside annulus of Zinn
This eventually drains into cavernous sinus
How is the inferior orbital vein formed and what does it drain into?
Inferior ophthalmic vein
usually forms anteriorly as plexus within inferomedial orbital fat
courses posteriorly along inferior rectus, also eventually drains into superior ophthalmic vein
communicates with pterygoid plexus via inferior orbital fissure
Relationship between the ciliary body, suspensory ligament, lens and refractive power during parasympathetic innervation
During parasympathetic innervation:
Ciliary muscle contract, the suspensory ligament relaxes, the lens become more round, refractive power increase, for seeing near objects.
Relationship between the ciliary body, suspensory ligament, lens and refractive power during sympathetic innervation
During sympathetic innervation:
Ciliary muscle relax, the suspensory ligament tenses, the lens becomes flat, refractive power decrease, for seeing flat objects.
What are the components of the lens ?
The capsule (BM), epithelium (single layer of cuboidal unstratified cells anterior and cuboidal at the equator) and fibres posteriorly
Describe the lens epithelium
Lens epithelium
It consists of simple cuboidal epithelium on the anterior surface
It consists of columnar epithelium at the equator.
The cell nucleus and cell body sink deeper into the lens as further cells are laid down externally
The mitotic activity is maximal around the equatorial zone known as germative zone
1) Formation start at 25 days gestation-development of optic vesicles
27-29 days-lens placode
30 days-lens vesicles
35 days-primary lens fibres
40 days-embryonic nucleus
7 weeks-secondary lens fibres
2) The lens placode is made of ectodermal cells that overlie the optic vesicles. The lens pit is the infolding of lens placode.
3) The lens vesicle is formed when the stalk of cells connecting the lens pit to surface ectoderm degenerates by apoptosis.
4) What remains is a single layer of cuboidal cells called the lens vesicle. The lens vesicle fills the optic cup which contains 2 layers:
Outer RPE
Neural retina
5) As the primary lens fibres elongate they fill the lumen of lens vesicles.
6) These elongated cells are called primary lens fibres.
7) Cells of anterior lens vesicle remain as a monolayer of cuboidal cells making the lens epithelium.
8) The lens capsule develops as basement membrane with the lens epithelium anteriorly and lens fibres posteriorly
9) The weight of the human lens at birth is 90mg at birth and increases 2mg per year.
The histology of the conjunctiva ?
Epithelial covering of stratified columnar cells
2 to 5 layers resting on lamina propia
Then at At limbus
Histology changes to stratified squamous nonkeratinized epithelium
Lamina propia forms papillae which are not found elsewhere on the conjunctiva
Stratified columnar to Stratified squamous non keratinized epithelium
Anterior relations of the posterior cranial fossa
Anterior relations
Superior border of petrous temporal bone and dorsum sellae
The cerebellum lies in the cerebellar fossa, in the squamous part of occipital bone.
Where does the medial canthal tendon lie in relation to the lacrimal sac?
Anterior
The endothelial cells of the iris capillaries features
The iris capillaries form the major site of the blood-aqueous barrier and are structurally specialized for this purpose. The iris capillaries are non-fenestrated, they are connected by numerous tight junctions, and they have a thickened basal lamina strengthened by perivascular collagenous hyalinised layers
Which cells are responsible for signal modulation reaching the ganglion cells of the retina:
Muller cells
bipolar cells
astrocytes
amacrine cells
Amacrine cells, together with horizontal cells, are believed to play a crucial role in signal modulation (mostly inhibitory) reaching the ganglion cells. Bipolar cells serve as a connector or intermediary between the photoreceptor and the ganglion cells. Astrocytes and Muller cells are glial cells and perform a supportive role both structurally and nutritionally.
Optic nerve
intraocular
orbital
intracanalicular
intracranial
The optic nerve segments are as follows:
intraocular: 1mm
orbital: 25-30 mm
intracanalicular: 4-10mm
intracranial: 10mm
The lateral and medial palpebral arteries are derived from what ?
The eyelids are supplied mainly by the medial and the lateral palpebral arteries. The lateral palpebral artery is derived from the lacrimal artery while the medial palpebral artery is derived from the dorsal nasal artery; these are all branches of the internal carotid artery.
What is the purpose of the ora serrata ?
It lies beneath what ?
Distance from the Schwalbe line - nasally and temporally
1) Separates the retina from pars plana
2) Distance from Schwalbe line:
5.75mm nasally; 6.50mm temporally
This distance is greater in myopia compared to hypertropia
diameter of eye 20mm circumference 63mm at ora serrata compared to 24mm and 75mm respectively at the equator
3) Lies beneath the Spiral of Tillaux externally
4) Importance: watershed zone between anterior and posterior vascular system
peripheral retina in region of ora serrata looks attenuated with malformed photoreceptors
You have a Parkinson’s patient who is complaining of severe dry eyes. You note from his ophthalmic history that he developed angle closure glaucoma a few months ago. Which of the following medications is most likely to be to associated with his symptoms?
Benztropine
Bromocriptine
Carbidopa
Levodopa
Selegiline
Benzotropine
Where does the LGN located ?
Thalmus
What is the blood supply to the choroid
- Blood supply
derived from ophthalmic artery, via branches of nasal and temporal main ciliary artery, anterior ciliary artery
ciliary artery branch into 10 to 20 short posterior ciliary artery
enters the globe via paraoptic and perimacular pattern before branching peripherally in wheel-shaped pattern - Paraoptic pattern
medial, lateral paraoptic PCA converge towards optic nerve head
form elliptical anastomotic circle known as circle of Haller and Zinn
clinical pearl: up to 23 percent of the population have incomplete circle of Haller and Zinn, this result in vulnerability to ischaemic attack to the optic nerve head - Perimacular pattern
PCA follow long, oblique course in the sclera, via the virtual suprachoroidal space -this gives recurrent branches to the macula and anterior choroid at the ora serrata
Pegatinib other name and MOA
1) Pegaptanib
Also known as Macugen
Short RNA oligonucleotide, aptamer
High specificity and affinity to VEGF165
How many optic fibres go to LGN and how many to pupillary nucleus?
Receive 70% of optic tract fibres; other 30% goes to pupillary nucleus
Which of the following forms the primary interstitial space of the retina
Henle and outter plexiform
Washout period of timolol?
4 weeks
Washour period of pilocarpine
3 days
MOA of action of tetracyclien?
Broad spectrum bacteriostatic against:
Effective against gram+ve, gram-ve
Rickettsia; Mycoplasma, Chlamydia
4) Systemic therapy often used to treat:
Chlamydial infection
Staphylococcal infection of meibomian gland
5) Anti-inflammatory properties used in meibomian gland disease (MGD):
Inhibition of matrix metalloproteinase, phospholipase A2
Often use for MGD, ocular rosacea
Action of pilocarpine
2) Actions of pilocarpine:
Miotic action on the iris, contraction of the longitudinal muscle of the ciliary body. This draws on the scleral spur and opens the uveotrabecular meshwork reducing outflow resistance
Reduces rate of aqueous secretion by reducing the blood flow to the ciliary body
Blocks uveoscleral drainage route of aqueous, leading to drainage through Schlemm’s canal.
SE of indirect muscarinic agonist
Cyst like proliferation of the iris pigment epithelium at the pupillary margin in children (reduced by phenylephrine drops)
