Orbit and Nasal cavity

Question 1

What is the general function of the eye’s design in image formation and movement control?

Answer 1

The eye is designed to form clear images through its anatomical structures and control movements via extraocular muscles and nerves (CN III, IV, VI).

Question 2

Why are the nasal passages and paranasal sinuses clinically important?

Answer 2

They are vital for airflow, mucosal health, and draining sinuses, and are associated with complications like sinusitis and nasal bleeding.

Question 3

Define diplopia and ptosis.

Answer 3

Diplopia is double vision due to misaligned eyes. Ptosis is drooping of the upper eyelid, often caused by dysfunction in the levator palpebrae superioris or superior tarsal muscle.

Question 4

How do extraocular muscles contribute to eye movements?

Answer 4

The extraocular muscles (recti and obliques) enable coordinated eye movements for focusing and tracking, with specific roles in elevation, depression, abduction, and adduction of the eyeball​

Question 5

How do you test the integrity of cranial nerves III, IV, and VI?

Answer 5

Eye movement testing evaluates CN III, IV, and VI by observing movements such as elevation, depression, and abduction. Dysfunction is seen in abnormal gaze positions and diplopia​

Question 6

What is Horner’s syndrome, and what causes it?

Answer 6

Horner’s syndrome results from cervical sympathetic chain injury, causing symptoms like ptosis, miosis, and anhidrosis due to denervation​

Question 7

How does the eye form a sharp image on the retina, and what is accommodation?

Answer 7

The eye’s cornea and lens focus light onto the retina; accommodation is the process where the lens changes shape to focus on near or distant objects​

Question 8

What occurs in glaucoma and cataracts?

Answer 8

Glaucoma: Increased intraocular pressure damages optic nerve fibers. Cataracts: The lens becomes cloudy, impairing light transmission to the retina​

Question 9

What is the function of tears?

Answer 9

Tears moisturize the eye and protect against infection, enabling clear vision by keeping the corneal surface smooth and hydrated​

Question 10

Outline the pathway and innervation of tear production and drainage.

Answer 10

Tears are produced in the lacrimal gland, drain into the lacrimal canaliculi, lacrimal sac, and nasolacrimal duct, then flow into the nasal cavity. Secretomotor innervation of the lacrimal gland is provided by CN VII​

Question 11

Describe the internal features of the nasal cavity and their functions.

Answer 11

The nasal cavity has a septum, conchae (superior, middle, and inferior), and meatuses for air passage. It connects to the paranasal sinuses, which open into these meatuses

Question 12

What is the blood supply and sensory innervation of the nasal cavity?

Answer 12

The nasal cavity is supplied by branches of the maxillary and ophthalmic arteries and receives sensory innervation from branches of the trigeminal nerve (CN V)

Question 13

Describe the location and drainage of the maxillary sinus.

Answer 13

The maxillary sinus, located under the orbit and above the upper teeth, drains into the middle meatus. Its high drainage opening can lead to fluid accumulation​

Question 14

How can eye development be linked to retinal detachment?

Answer 14

Retinal detachment is related to developmental issues in the eye that may compromise the adherence of retinal layers

Question 15

What are the major anatomical boundaries and relations of the orbit?

Answer 15

The borders and anatomical relations of the bony orbit are as follows:

Roof (superior wall) – Formed by the frontal bone and the lesser wing of the sphenoid. The frontal bone separates the orbit from the anterior cranial fossa.
Floor (inferior wall) – Formed by the maxilla, palatine and zygomatic bones. The maxilla separates the orbit from the underlying maxillary sinus.
Medial wall – Formed by the ethmoid, maxilla, lacrimal and sphenoid bones. The ethmoid bone separates the orbit from the ethmoid sinus.
Lateral wall – Formed by the zygomatic bone and greater wing of the sphenoid.
Apex – Located at the opening to the optic canal, the optic foramen.
Base – Opens out into the face, and is bounded by the eyelids. It is also known as the orbital rim.

Question 16

What is the shape of the orbit, and what structures are contained within it?

Answer 16

The orbit is conical or pyramidal, with the base facing forward and the apex pointing toward the cranial cavity. It contains the eyeball, lacrimal gland, extraocular muscles, neurovascular bundles, and orbital fat, which cushions and supports the structures within

Question 17

What are the major openings in the orbit, and what passes through them?

Answer 17

Key openings in the orbit include the optic canal (transmits the optic nerve and ophthalmic artery), superior orbital fissure (for cranial nerves III, IV, V1, and VI), and inferior orbital fissure (connecting with the infratemporal and pterygopalatine fossae, Infraorbital nerve, artery and vein. Inferior ophthalmic vein. Zygomatic nerve.

Question 18

Describe the role of the superior tarsal (Müller’s) muscle in the eye.

Answer 18

The superior tarsal muscle, a smooth muscle attached to the levator palpebrae superioris, assists in elevating the upper eyelid. It is innervated by sympathetic fibers, so damage to these can lead to partial ptosis (drooping)​

Question 19

What are Meibomian glands, and what is their function?

Answer 19

Meibomian glands are modified sebaceous glands along the eyelid rims that produce an oily substance (meibum), preventing evaporation of the eye’s tear film and helping to maintain moisture​

Question 20

What is the function of the lacrimal canaliculi and nasolacrimal duct?

Answer 20

The lacrimal canaliculi drain tears from the eye surface into the lacrimal sac, which then empties into the nasal cavity via the nasolacrimal duct, allowing tear drainage into the inferior nasal meatus​

Question 21

Describe the bony components of the nasal septum.

Answer 21

The nasal septum consists of both bone (including the perpendicular plate of the ethmoid and vomer) and cartilage, which divides the nasal cavity into left and right halves​

Question 22

What structures form the lateral wall of the nasal cavity, and what is the significance of the conchae?

Answer 22

The lateral wall contains the superior, middle, and inferior conchae. These bony projections increase the surface area for air filtration, humidification, and warming, with spaces beneath each (meatuses) that allow drainage from the paranasal sinuses​

Question 23

What are the paranasal sinuses, and which is most prone to infection?

Answer 23

The paranasal sinuses (frontal, ethmoid, sphenoid, maxillary) are air-filled spaces in facial bones. The maxillary sinus is particularly prone to infection due to its high drainage opening, which can trap fluid​

Question 24

How does the rich blood supply of the nasal cavity contribute to its vulnerability?

Answer 24

The nasal cavity has an extensive blood supply with rich anastomoses, especially around the septum, making it prone to bleeding (epistaxis), especially from trauma or inflammation​

Question 25

What is the significance of the ophthalmic artery and its branches?

Answer 25

The ophthalmic artery supplies blood to the orbit, including the retina via the central retinal artery. Blockage of this artery can lead to vision loss due to retinal ischemia​

Question 26

What is the role of the cribriform plate in the nasal cavity?

Answer 26

The cribriform plate, part of the ethmoid bone, forms the roof of the nasal cavity. It allows passage of olfactory nerve fibers from the nasal mucosa to the olfactory bulb in the brain​