DR 3 - Orbit and Nasal Cavity

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Questions and Answers

Which cranial nerves supply the extraocular muscles?

Cranial nerves 1, 2, and 3

Cranial nerves 2, 3, and 4

Cranial nerves 5, 6, and 7

Cranial nerves 3, 4, and 6 (correct)

What is the main nerve supply to the eye?

Cranial nerve 3

Cranial nerve 4

Cranial nerve 6

Cranial nerve 2 (correct)

Which bone forms the roof of the orbit?

Sphenoid bone

Maxillary bone

Frontal bone (correct)

Ethmoid bone

What is the shape of the orbit?

Pyramidal Signup and view all the answers

Which of the following can cause reduced perfusion to the eyeball and the optic nerve resulting in potential loss of vision?

Intraorbital pressure increases Signup and view all the answers

Which muscle is responsible for lifting the upper eyelid?

Levator palpebrae superioris Signup and view all the answers

What is the consequence of total compression of the right optic nerve by an intraorbital tumor on the right side?

Monocular blindness in the right eye Signup and view all the answers

What is the function of the oblique muscles in the eye?

To move the eye in a circular motion Signup and view all the answers

Which nerve provides somatic sensory innervation to the eye, lacrimal gland, orbit, and the skin around the orbit and forehead?

Ophthalmic nerve (V1) Signup and view all the answers

Which nerve runs just under the roof of the orbit and has two terminal branches, the supraorbital nerve and the supratrochlear nerve?

Frontal nerve Signup and view all the answers

Which nerve carries pain and touch sensation from the cornea via its long posterior ciliary branches and supplies the structures of the eye itself, ethmoid sinus, and the skin over the nose?

Nasociliary nerve Signup and view all the answers

Which nerve carries somatic sensory information from the lacrimal gland, lateral conjunctiva, and a small area of skin over the lateral portion of the eyelids?

Lacrimal nerve Signup and view all the answers

Which cranial nerve is responsible for innervating the medial rectus muscle?

Oculomotor nerve (CN 3) Signup and view all the answers

What is the clinical presentation of oculomotor nerve palsy?

Drooped eyelid and dilated pupil Signup and view all the answers

Why is abducens nerve palsy considered an ominous sign?

It is the first cranial nerve affected in raised intra-cranial pressure Signup and view all the answers

What is the function of the conchae in the nasal cavity?

To warm and humidify inspired air Signup and view all the answers

Which of the following sinuses is located within the frontal bone?

Frontal sinus Signup and view all the answers

Which nerve(s) innervate the frontal sinus?

V1 - Ophthalmic, frontal branch Signup and view all the answers

Which sinuses are innervated by both the V1 - Ophthalmic and V2 - Maxillary branches of the trigeminal nerve?

Sphenoid and maxillary sinuses Signup and view all the answers

Which artery is involved in anterior nosebleeds?

External carotid artery Signup and view all the answers

Which cranial nerves are involved in allowing and opposing superior movement of the eye?

CN III and CN IV Signup and view all the answers

What structures of the orbit and nasal cavity can be identified on the CT scan?

Zygoma and conchae Signup and view all the answers

Which plane was the CT scan taken in?

Coronal Signup and view all the answers

Which muscle is responsible for the inability to move the right eye superiorly when adducted?

Superior rectus Signup and view all the answers

Are there any evidence of bone fractures in the CT scan?

No, there are no bone fractures Signup and view all the answers

What was the main complaint of the patient when they came to the emergency department?

Double vision Signup and view all the answers

What nerve supplies the superior oblique muscle?

Trochlear nerve Signup and view all the answers

What is the main artery supplying the orbit?

Ophthalmic artery Signup and view all the answers

What is the result of a blockage of the central retinal artery?

Sudden loss of sight in affected eye Signup and view all the answers

If a patient is asked to look up and to the right, which muscles of the left eye would you be testing?

Superior and inferior recti muscles Signup and view all the answers

Study Notes

Cranial Nerves and Eye Movement

Cranial nerves III, IV, and VI supply the extraocular muscles
The oculomotor nerve (cranial nerve III) is responsible for innervating the medial rectus muscle
Cranial nerve III is also responsible for superior movement of the eye
The trochlear nerve (cranial nerve IV) supplies the superior oblique muscle
The abducens nerve (cranial nerve VI) is involved in lateral movement of the eye

Orbit and Eye Anatomy

The frontal bone forms the roof of the orbit
The orbit is conical in shape
The levator palpebrae superioris muscle is responsible for lifting the upper eyelid

Nerve Supply to the Eye

The nasociliary nerve provides somatic sensory innervation to the eye, lacrimal gland, orbit, and the skin around the orbit and forehead
The frontal nerve runs just under the roof of the orbit and has two terminal branches, the supraorbital nerve and the supratrochlear nerve
The nasociliary nerve carries pain and touch sensation from the cornea via its long posterior ciliary branches and supplies the structures of the eye itself, ethmoid sinus, and the skin over the nose
The lacrimal nerve carries somatic sensory information from the lacrimal gland, lateral conjunctiva, and a small area of skin over the lateral portion of the eyelids

Clinical Presentations

Oculomotor nerve palsy presents with drooping of the eyelid, double vision, and loss of eye movement
Abducens nerve palsy is considered an ominous sign as it can indicate increased intracranial pressure or tumors
Total compression of the right optic nerve by an intraorbital tumor on the right side can result in loss of vision

Nasal Cavity Anatomy

The conchae in the nasal cavity function to warm, humidify, and filter air
The frontal sinus is located within the frontal bone and is innervated by the supratrochlear and supraorbital nerves
The ethmoid sinus is innervated by the nasociliary nerve
The sphenoid sinus is innervated by the maxillary nerve

Imaging and Vasculature

A CT scan can identify structures of the orbit and nasal cavity
The CT scan is typically taken in the axial plane
The ophthalmic artery is the main artery supplying the orbit
A blockage of the central retinal artery can result in blindness

Clinical Scenario

A patient presenting with inability to move the right eye superiorly when adducted may have a problem with the superior rectus muscle or the inferior oblique muscle
The presence of bone fractures on a CT scan can indicate trauma
A patient complaining of vision loss or double vision may have a problem with the cranial nerves or orbit.

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Description

Test your knowledge on the paranasal sinuses and their anatomy. Identify the different sinuses and learn about their drainage pathways and innervation.