Orbit And Content

Question 1

What are the four walls of the bony orbit?

Answer 1

Roof: Frontal bone, Lesser wing of sphenoid

Floor: Maxilla, Zygomatic, Palatine bone

Medial Wall: Frontal process of maxilla, Lacrimal bone, Orbital plate of ethmoid, Lesser wing of sphenoid

Lateral Wall: Zygomatic bone, Greater wing of sphenoid

Question 2

What structures pass through the optic canal?

Answer 2

Optic nerve

Ophthalmic artery

Meninges

Sympathetic fibers

Question 3

What are the three tunics of the eyeball?

Answer 3

Fibrous Tunic: Sclera and cornea

Vascular Tunic (Uveal tract): Choroid, ciliary body, iris

Nervous Tunic: Retina

Question 4

What is the function of the ciliary body?

Answer 4

Accommodation: Adjusts the shape of the lens for near vision.

Production of aqueous fluid.

Question 5

What is the macula lutea, and what is its significance?

Answer 5

A small, yellowish area of the retina, 3mm lateral to the optic disc.

Contains the fovea centralis, the most sensitive part of the retina for detailed vision (cones only).

Question 6

What is glaucoma, and what causes it?

Answer 6

Glaucoma is increased intraocular pressure.

It is caused by blockage of aqueous fluid flow(Canal of schlemm) or overproduction of aqueous humor.

Question 7

Function of medial rectus

Answer 7

Adduction

Question 8

Function of lateral rectus

Answer 8

Abduction

Question 9

Function of Superior rectus

Answer 9

Elevation, adduction, medial rotation

Question 10

Function of Inferior rectus

Answer 10

Depression, adduction, lateral rotation

Question 11

Function of Superior oblique

Answer 11

Depression, abduction, medial rotation

Question 12

Function of inferior oblique

Answer 12

Elevation, abduction, lateral rotation

Question 13

Levator palpebrae superioris

Answer 13

Elevates the upper eyelid.

Question 14

What is Horner’s Syndrome, and what are its symptoms?

Answer 14

Horner’s Syndrome is caused by damage to the sympathetic nerves.

Symptoms:

Partial ptosis (drooping eyelid)

Miosis (pupillary constriction)

Anhydrosis (reduced or absent sweating on the face)

Question 15

What is the lacrimal apparatus, and what are its components?

Answer 15

Lacrimal gland (orbital and palpebral parts)

Lacrimal papilla

Lacrimal punctum

Lacrimal canaliculus

Lacrimal sac

Nasolacrimal duct

Question 16

What is the difference between a stye (hordeolum) and a chalazion?

Answer 16

Stye (Hordeolum): Infection of the oil glands associated with eyelash follicles.

Chalazion: Blockage of a meibomian gland, causing a cyst.

Question 17

What is the Tenon’s capsule, and what is its function?

Answer 17

Tenon’s capsule is a fascial sheath surrounding the eyeball.

It is attached anteriorly to the sclera at the corneoscleral junction and blends posteriorly with the sheath at the entrance of the optic nerve.

Function: Provides a smooth surface for eye movement and supports the eyeball.

Question 18

What is the optic disc, and why is it called the “blind spot”?

Answer 18

The optic disc is the point where the optic nerve enters the retina.

It is called the “blind spot” because it lacks photoreceptors (rods and cones) and is insensitive to light.

Question 19

What is the canal of Schlemm, and what is its function?

Answer 19

The canal of Schlemm is a circular channel at the corneoscleral junction.

It drains aqueous fluid from the anterior chamber into the venous system.

Question 20

What is retinal detachment, and what are its consequences?

Answer 20

Retinal detachment occurs when the retina separates from the underlying choroid layer.

Consequences: Loss of vision in the affected area, which can lead to blindness if not treated.

Question 21

What is the ciliary ganglion, and what is its role?

Answer 21

The ciliary ganglion is a parasympathetic ganglion located behind the eye.

It receives preganglionic fibers from the Edinger-Westphal nucleus and sends postganglionic fibers to the ciliary muscle and sphincter pupillae for accommodation and pupil constriction.

Question 22

What structures pass through the superior orbital fissure

Answer 22

Oculomotor nerve (CN III)

Trochlear nerve (CN IV)

Ophthalmic division of the trigeminal nerve (CN V1)

Abducens nerve (CN VI)

Superior ophthalmic vein

Question 23

What is the inferior orbital fissure, and what structures pass through it?

Answer 23

The inferior orbital fissure is an opening between the greater wing of the sphenoid and the maxilla.

Structures passing through it:

Infraorbital nerve

Zygomatic nerve

Inferior ophthalmic vein

Question 25

What is the conjunctiva, and what are its two parts?

Answer 25

The conjunctiva is a transparent membrane covering the front of the eye and lining the eyelids. Its two parts: Palpebral conjunctiva: Lines the eyelids. Orbital conjunctiva: Covers the eyeball.

Question 26

What is the lens, and what is its role in vision?

Answer 26

he lens is a transparent, biconvex structure in the eye. Its role: Refracts light to focus it on the retina, allowing for clear vision.

Question 27

What is the orbital fascia (periorbita), and what is its function?

Answer 27

The orbital fascia is the periosteum lining the orbital bones. Function: Provides attachment points for muscles, tendons, and ligaments.

Question 28

What are the main arteries supplying the orbit, and what do they supply?

Answer 28

Central Artery of the Retina: Supplies the retina.

Question 29

How does venous drainage occur in the orbit?

Answer 29

Superior Ophthalmic Vein: Drains into the cavernous sinus. Inferior Ophthalmic Vein: Drains into the pterygoid plexus of veins. There is communication between the two veins for alternative drainage pathways.

Question 30

What are the layers of the eyelids, and what structures are found in each layer?

Answer 30

Skin: Outermost layer. Subcutaneous Tissue: Contains loose connective tissue. Orbital Septum (Tarsal Plate): Provides structural support. Tarsal (Meibomian) Glands: Secrete oils to prevent tear evaporation. Palpebral Conjunctiva: Lines the inner surface of the eyelids.

Question 31

What is the hyaloid artery, and what happens to it after birth?

Answer 31

he hyaloid artery is a fetal structure that supplies blood to the developing lens and retina. After birth, it disappears, leaving behind the hyaloid canal in the vitreous humor.

Question 32

What is the visual cortex, and where is it located?

Answer 32

The visual cortex is the part of the brain that processes visual information. It is located in the occipital lobe.

Question 33

What nerve innervates the conjnctiva?

Answer 33

Lacrimal nerve

Question 33

What is the pupillary light reflex, and which nerves are involved?

Answer 33

he pupillary light reflex is the constriction of the pupil in response to light. Nerves involved: Afferent: Optic nerve (CN II). Efferent: Oculomotor nerve (CN III)

Question 33

What are the orbital relations, and what structures are adjacent to each wall of the orbit?

Answer 33

Roof: Anterior cranial fossa and frontal lobe of the brain. Floor: Maxillary sinus. Medial Wall: Nasal cavity and ethmoidal air sinuses. Lateral Wall: Temporal fossa.

Question 33

What is a blowout fracture, and what are its symptoms?

Answer 33

A blowout fracture is a fracture of the orbital floor or medial wall, often caused by blunt trauma. Symptoms: Diplopia (double vision), enophthalmos (sunken eye), and infraorbital nerve damage.