EYE Flashcards
The orbit and its content
Layers of the orbit
Content of the orbit
Fascia which surrounds the eyeball around the sclera
BULBAR FASCIA (TENON’S CAPSULE)
The … and the … are transparent and do not have blood vessels
Lens, cornea
The … travels from ciliary body to the cornea so as to nourish it.
Aqueous humour
The ciliary muscle is attached to the …., so as to relax and contract the lens capsule and the lens.
fibers of ciliary zonule
What might happen if pressure increases in the SINUS VENOSUS SCLERAE (Schlemm’s canal)?
Glaucoma
LAYERS OF THE EYEBALL
The retina originates from an evagination of the secondary prosencephalon (hypothalamus):
The optic vesicle, and later, the optic cup
DEVELOPMENT OF THE EYE
• inner layer of the optic cup – …
• outer layer of the optic cup – … (pigmentary epithelium)
• invaginating lens placode – …
• optic stalk – …
- neural retina
- non‐ neural retina
- lens of the eye
- optic nerve
The optic cup has 2 layers: internal and external, separated by an INTRARETINAL SPACE.
EXTERNAL LAYER gives rise to layer … of the retina.
INTERNAL LAYER to layers …
If internal and external layers separate (with a problem in intraretinal space), … could happen.
1
2 to 10
RETINAL DETACHMENT
Transformation of the optic stalk in the optic nerve
Embryonic origin of the extrinsic muscles of the eye.
Where do they insert?
Somitomeres (non‐segmented paraaxial mesoderm).
These muscles insert into the sclera, except for the levator palpebrae (which inserts in the superior lid to elevate it).
Extrinsic muscles of the eye
Origin of the four rectus muscles
common tendinous ring: thickening of periorbita around the optic canal and SOF
Which muscles insert in the anterior quadrant of the sclera and pull the eyeball backwards?
Rectus muscles
Which muscles insert in the posterior quadrant of the sclera and pull the eyeball slightly forwards?
The obliques
1st nerve that becomes affected with an aneurysm
VI CN (Abducens). The patient might present diplopia.
Which nerve is this one? What does it innervate?
TROCHLEAR nerve (IV), it innervates the superior oblique muscle
Which nerves are these ones? What do they innervate?
… muscles pull eyeball lateral & medially, respectively
Lateral & medial rectus
Because of different axis of orbit & eyeball, … muscles pull the eyeball medially as well as elevate and depress it
superior & inferior rectus
Because of their oblique course, the … muscles pull the eyeball laterally as well as down and up
superior & inferior oblique
Pure elevation is produced by the … mhuscles acting together
superior rectus & inferior oblique
Pure depression is produced by … muscles
IR & SO
Name the intrinsic muscles of the eye, their function and their origin
Origin: neural crest cells
- constrictor m of the pupil – contracts the pupil
- ciliary muscle – relaxes the lens for accommodation
- dilator m of the pupil – dilates the pupil
Innervation of intrinsic muscles of the eye
AUTONOMIC INNERVATION
- Contrisctor m of the pupil: PS with III
- Ciliary muscle: PS with III
- Dilator m of the pupil: sympathetic fibers
INTRINSIC MUSCLES OF THE EYE INNERVATION
The eye is supplied by branches of the … that accompany the …
Ophthalmic artery, sensory nerves
The … provides supply for the layers 2 to 10 of the retina
Central artery of the retina
IMPORTANT: it is a terminal branch, if there is an aneurysm, the retina will become prived of blood flow.
The cornea is supplied by blood vessels (T/F)
False: THERE ARE NO BLOOD VESSELS IN THE CORNEA
It is supplied by aqueous humour
central artery of the retina supplies …
ant and posterior ciliary aa supply …
- layers 2 to 10 of the retina
– layer I, vascular and fibrous layers
Branches of the central artery and vein of retina…
Enter/exit at the optic disc or papilla and are absent at the fovea centralis
The branches of the central artery of the retina have NO ANASTOMOSES.
Venous drainage of the eyeball
Syndrome in which sympathetic fibers are lesioned on one side of the face.
- Palpebral ptosis: no basal sympathetic tone (the superior tarsus lacks of innervation)
• Miosis: pupil is contracted by the PS system
• Lack of sweating (anhydrosis)
HORNER’S SYNDROME
Lacrimal system
Lacrimal system is under … control
PS
The contraction of the … compresses the lacrimal sac and produces nasolacrimal drainage
orbicularis oculi m