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Questions and Answers
The fascia bulbi, also known as the Tenon's capsule, is situated at the anterior part of the eyeball, extending from the optic nerve attachment to the corneoscleral junction.
The fascia bulbi, also known as the Tenon's capsule, is situated at the anterior part of the eyeball, extending from the optic nerve attachment to the corneoscleral junction.
False (B)
The internal layer of the fascia bulbi is described as thick and distinctly separate from the sclera.
The internal layer of the fascia bulbi is described as thick and distinctly separate from the sclera.
False (B)
The tendons of the four recti and two obliques muscles perforate the inner layer of the fascia bulbi.
The tendons of the four recti and two obliques muscles perforate the inner layer of the fascia bulbi.
False (B)
The lateral check ligament, a thickening of the tubular prolongation over the lateral rectus, attaches to the marginal tubercle located on the parietal bone.
The lateral check ligament, a thickening of the tubular prolongation over the lateral rectus, attaches to the marginal tubercle located on the parietal bone.
The medial check ligament is connected to the anterior lacrimal crest on the lacrimal bone.
The medial check ligament is connected to the anterior lacrimal crest on the lacrimal bone.
The suspensory ligament of Lockwood is formed by the thickening of the superior portion of the fascial sheath.
The suspensory ligament of Lockwood is formed by the thickening of the superior portion of the fascial sheath.
The eyeball rests directly upon the floor of the orbit, providing it with primary support.
The eyeball rests directly upon the floor of the orbit, providing it with primary support.
Removal of the maxilla, including the orbital side walls up to the level of the marginal tubercle, will typically result in the immediate descent of the eye.
Removal of the maxilla, including the orbital side walls up to the level of the marginal tubercle, will typically result in the immediate descent of the eye.
During eye movements, the eye rotates around a variable center that shifts based on the direction of gaze.
During eye movements, the eye rotates around a variable center that shifts based on the direction of gaze.
Posterior displacement of the eye is prevented by the bony attachments of the recti, orbital fat, and the forward pull of the palpebral muscles.
Posterior displacement of the eye is prevented by the bony attachments of the recti, orbital fat, and the forward pull of the palpebral muscles.
The nasociliary nerve is the second branch of the ophthalmic nerve.
The nasociliary nerve is the second branch of the ophthalmic nerve.
The inferior division of the oculomotor nerve supplies the inferior and medial rectus muscles in the orbit.
The inferior division of the oculomotor nerve supplies the inferior and medial rectus muscles in the orbit.
The sympathetic fibres that the nasociliary nerve carries originated from the Edinger-Westphal nucleus.
The sympathetic fibres that the nasociliary nerve carries originated from the Edinger-Westphal nucleus.
The abducent nerve innervates the lateral rectus muscle.
The abducent nerve innervates the lateral rectus muscle.
The parasympathetic root of the ciliary ganglion comes from the nerve to the superior oblique.
The parasympathetic root of the ciliary ganglion comes from the nerve to the superior oblique.
The short ciliary nerves contain fibres from all three roots of the ciliary ganglion.
The short ciliary nerves contain fibres from all three roots of the ciliary ganglion.
The oculomotor nerve's superior division provides nerve supply to the superior rectus and levator palpebrae muscles.
The oculomotor nerve's superior division provides nerve supply to the superior rectus and levator palpebrae muscles.
The optic nerve lies lateral and inferior to the oculomotor and nasociliary nerves.
The optic nerve lies lateral and inferior to the oculomotor and nasociliary nerves.
The infratrochlear nerve supplies the skin of the upper lid and the bridge of the nose.
The infratrochlear nerve supplies the skin of the upper lid and the bridge of the nose.
The abducent nerve travels alongside the nasociliary and optic nerves to reach the lateral rectus muscle.
The abducent nerve travels alongside the nasociliary and optic nerves to reach the lateral rectus muscle.
The check ligaments discourage anterior displacement of the eye.
The check ligaments discourage anterior displacement of the eye.
Enophthalmos can result from an increase in orbital fat volume, such as in hyperthyroidism.
Enophthalmos can result from an increase in orbital fat volume, such as in hyperthyroidism.
The volume of orbital fat is significantly affected by changes in general body fat.
The volume of orbital fat is significantly affected by changes in general body fat.
The oblique muscles exert a backward pull on the eye.
The oblique muscles exert a backward pull on the eye.
The optic nerve enters the orbit through the superior orbital fissure.
The optic nerve enters the orbit through the superior orbital fissure.
The frontal and infraorbital nerves give off numerous branches to the orbital contents.
The frontal and infraorbital nerves give off numerous branches to the orbital contents.
The infraorbital nerve supplies some of the lower teeth.
The infraorbital nerve supplies some of the lower teeth.
The zygomatic nerve's communicating branch to the lacrimal nerve carries motor fibers for the lacrimal gland.
The zygomatic nerve's communicating branch to the lacrimal nerve carries motor fibers for the lacrimal gland.
The ophthalmic artery crosses the optic nerve from medial to lateral.
The ophthalmic artery crosses the optic nerve from medial to lateral.
The ciliary ganglion is situated medial to the optic nerve.
The ciliary ganglion is situated medial to the optic nerve.
The postganglionic fibers primarily supply the ciliary body's muscle for accommodation.
The postganglionic fibers primarily supply the ciliary body's muscle for accommodation.
Only 3% of the postganglionic fibers supply the sphincter pupillae, which has about 50 motor units.
Only 3% of the postganglionic fibers supply the sphincter pupillae, which has about 50 motor units.
Both long and short ciliary nerves carry sensory fibers for the cornea.
Both long and short ciliary nerves carry sensory fibers for the cornea.
The supraorbital artery is one of the terminal branches of the ophthalmic artery.
The supraorbital artery is one of the terminal branches of the ophthalmic artery.
The central artery is an end artery that supplies the optic nerve and retina.
The central artery is an end artery that supplies the optic nerve and retina.
The inferior ophthalmic vein drains directly into the cavernous sinus.
The inferior ophthalmic vein drains directly into the cavernous sinus.
The ophthalmic artery passes through the optic canal along with the optic nerve.
The ophthalmic artery passes through the optic canal along with the optic nerve.
The anterior ciliary arteries pierce the anterior part of the eye from the muscular branches to the recti.
The anterior ciliary arteries pierce the anterior part of the eye from the muscular branches to the recti.
Both the ophthalmic artery and veins supply the ethmoidal air cells.
Both the ophthalmic artery and veins supply the ethmoidal air cells.
Lymphatics of the orbit drain to preauricular and parotid lymph nodes.
Lymphatics of the orbit drain to preauricular and parotid lymph nodes.
Flashcards
Fascial sheath of the eye
Fascial sheath of the eye
A protective layer around the eyeball that supports it and allows movement.
Tenon's capsule
Tenon's capsule
Another name for the fascial sheath of the eye, extending from corneoscleral junction to optic nerve.
Lateral check ligament
Lateral check ligament
A thickening of the sheath over the lateral rectus muscle, aiding eye stability.
Marginal tubercle
Marginal tubercle
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Medial check ligament
Medial check ligament
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Suspensory ligament of Lockwood
Suspensory ligament of Lockwood
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Eye mobility
Eye mobility
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Orbital fat
Orbital fat
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Recti muscles
Recti muscles
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Displacement prevention
Displacement prevention
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Medial Rectus
Medial Rectus
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Lateral Rectus
Lateral Rectus
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Exophthalmos
Exophthalmos
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Enophthalmos
Enophthalmos
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Optic Nerve
Optic Nerve
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Trochlear Nerve
Trochlear Nerve
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Oculomotor Nerve
Oculomotor Nerve
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Infraorbital Nerve
Infraorbital Nerve
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Zygomatic Nerve
Zygomatic Nerve
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Ciliary Ganglion
Ciliary Ganglion
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Postganglionic fibers
Postganglionic fibers
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Ciliary body
Ciliary body
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Ophthalmic artery
Ophthalmic artery
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Central artery
Central artery
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Posterior ciliary arteries
Posterior ciliary arteries
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Superficial ophthalmic vein
Superficial ophthalmic vein
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Inferior ophthalmic vein
Inferior ophthalmic vein
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Lymphatic drainage
Lymphatic drainage
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Sphincter pupillae
Sphincter pupillae
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Anastomosis
Anastomosis
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Oculomotor nerve divisions
Oculomotor nerve divisions
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Abducent nerve
Abducent nerve
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Superior division of Oculomotor
Superior division of Oculomotor
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Inferior division of Oculomotor
Inferior division of Oculomotor
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Nasociliary nerve
Nasociliary nerve
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Short ciliary nerves
Short ciliary nerves
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Long ciliary nerves
Long ciliary nerves
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Sensory root of ciliary ganglion
Sensory root of ciliary ganglion
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Parasympathetic root of ciliary ganglion
Parasympathetic root of ciliary ganglion
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Study Notes
Eye Stability
- Eye is suspended in orbit by suspensory ligament (of Lockwood), not resting on the orbital floor.
- Maxilla removal up to marginal tubercle level won't dislodge eye.
- Above the marginal tubercle, eye is supported by attachments of suspensory ligament. Removal of bone causes eye descent and diplopia.
Eye Movement and Stability
- Eye rotation occurs about a fixed center (geometric center of the eye).
- Eye movement does not cause it to pop in/out of socket.
Factors Preventing Posterior Displacement
- Bony attachments of recti muscles.
- Orbital fat acts as cushion. Increased volume leads to exophthalmos; decreased volume leads to enophthalmos.
- Forward pull of obliques muscles plays a role.
Check Ligaments
- Lateral check ligament thickens lateral sheath, connected to marginal tubercle (palpable elevation on zygomatic bone).
- Medial check ligament thickens medial sheath, connected to posterior lacrimal crest on lacrimal bone.
Specific Eye Muscles
- Inferior Oblique: Muscle that pierces the suspensory ligament and plays a role in forward eye movement.
Nerves of the Orbit
Nerves Inside the Cone of Muscles
- Oculomotor nerve (3 cranial) enters tendinous ring in two divisions (superior and inferior).
- Abducent nerve (6 cranial) sinks into lateral rectus muscle.
Nerves Outside the Cone of Muscles
- Trochlear nerve (4 cranial) runs forward to superior oblique muscle.
- Lacrimal nerve, a branch of ophthalmic nerve, runs forward, and picks up a zygomatic nerve secretomotor branch for lacrimal gland.
- Frontal nerve, branches into supratrochlear and supraorbital nerve.
- Nasociliary nerve, third branch of ophthalmic nerve, changes names (anterior ethmoidal, external nasal), passes along ophthalmic artery, and branches into posterior ethmoidal.
Fibrous Ring
- Nerves of extraocular muscles pass through fibrous ring. Optic nerve, above this group
- Sensory root of ciliary ganglion passes through fibrous ring to supply sensory input to entire eye (cornea, sclera, iris, ciliary body).
- Sympathetic root passes through fibrous ring, providing vasoconstriction to eye vessels.
- Parasympathetic root, from nerve to inferior oblique, relays in ciliary ganglion to supply accommodation muscles.
Ciliary Ganglion
- Located laterally beside optic nerve, about a third of the way down from optic canal.
- Composed of 3 roots (sensory, sympathetic, parasympathetic).
- Short ciliary nerves are branches of ganglion that pierce sclera and supply muscles of ciliary body and sphincter pupillae.
Blood Supply
- Intracranial optic nerve is supplied by anterior cerebral artery.
- Orbital part (posterior 2cm) is supplied by ophthalmic artery.
- Anterior 1cm is supplied by central artery.
- Central artery is end artery and important to the retina.
- Ophthalmic artery spirals around lateral optic nerve and has branches to supply muscles, lacrimal gland, and eye itself (central artery for retina, posterior ciliary arteries to choroid).
Ophthalmic Veins
- Superior ophthalmic vein drains orbit, communicating with angular vein and drains into cavernous sinus.
- Inferior ophthalmic vein drains into pterygoid plexus.
Lymphatics
- Orbit lymphatics drain to preauricular and parotid lymph nodes, and into deep cervical nodes.
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Description
Explore the fascinating mechanics of eye stability and movement in this quiz. Learn about the suspensory ligaments, muscle attachments, and the factors that prevent posterior displacement of the eye. Test your knowledge on the anatomical features that contribute to eye rotation and stability.
