Eye Muscle Quiz: Test Your Knowledge of Extraocular Muscles

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Questions and Answers

What is the primary function of the common tendinous ring that surrounds the optic canal?

To provide a point of origin for the recti muscles (correct)

To anchor the eyeball in a fixed position within the orbit

To protect the optic nerve as it exits the orbit

To facilitate the movement of the eyeball within the orbit

Which of the following muscles is responsible for abducting the eyeball?

Superior rectus

Lateral rectus (correct)

Medial rectus

Inferior oblique

What is the role of the fascial sheath (Tenon's capsule) in the suspensory apparatus of the eyeball?

It allows for smooth movement of the eyeball within the orbit (correct)

It provides a rigid framework to hold the eyeball in place

It anchors the eyeball to the bony walls of the orbit

It transmits the forces generated by the extrinsic eye muscles

What is the function of the episcleral space between the fascial sheath and the outer layer of the eyeball?

To facilitate the smooth movement of the eyeball within the orbit Signup and view all the answers

Which nerve is responsible for innervating the lateral rectus muscle?

Abducens nerve (CN VI) Signup and view all the answers

Which of the following muscles is responsible for depressing the eyeball?

Inferior rectus Signup and view all the answers

What is the function of the suspensory ligament of the eyeball?

To hold the eyeball in place and support the lens Signup and view all the answers

Where are the medial and lateral check ligaments attached?

Lacrimal and zygomatic bones Signup and view all the answers

What is enophthalmos?

Retraction of the eyeball into the orbit Signup and view all the answers

Which nerve supplies the lateral rectus muscle?

Abducens (CN VI) Signup and view all the answers

Where do the optic nerves begin?

At the lamina cribrosa of the sclera Signup and view all the answers

What is the function of the central retinal artery?

Supplies blood to internal aspect of the retina Signup and view all the answers

Which arteries directly supply the choroid and nourish the outer nonvascular layer of the retina?

Choriocapillaris Signup and view all the answers

Where is the scleral venous sinus located?

Encircling the anterior chamber of the eyeball Signup and view all the answers

What is one of the functions of the lacrimal fluid secreted by lacrimal gland?

Moistens and lubricates surfaces of conjunctiva and cornea Signup and view all the answers

What is a significant role of check ligaments in relation to eye movement?

To maintain correct tension to limit eye movement in certain directions Signup and view all the answers

What is the main action of the levator palpebrae superioris muscle?

Elevates the superior eyelid Signup and view all the answers

Which of the following nerves innervates the levator palpebrae superioris muscle?

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

What is the arrangement of the levator palpebrae superioris muscle as it approaches its distal attachment?

It broadens into a bilaminar aponeurosis Signup and view all the answers

Which of the following structures is NOT one of the extraocular muscles?

Levator palpebrae superioris Signup and view all the answers

What is the function of the deep lamina of the levator palpebrae superioris muscle?

Produces additional widening of the palpebral fissure during sympathetic response Signup and view all the answers

Which of the following structures is responsible for suspending the eyeball within the orbit?

Suspensory ligament of the eyeball Signup and view all the answers

Study Notes

Anatomy of the Eye

The retina consists of two layers: neural and pigmented layers
- Neural layer is light receptive
- Pigmented layer reinforces light-absorbing property of the choroid in reducing scattering of light in the eyeball
The inner layer (inner coat) terminates at the ora serrata (serrated edge)

The Retina

Optic part of the retina is sensitive to visual light rays
Anterior continuation of the pigmented layer and a layer of supporting cells
Extends over the ciliary body (ciliary part of retina) and the posterior surface of the iris (iridial part of the retina) to the pupillary margin

Refractive Media and Compartments of the Eyeball

Refractive media of the eyeball include: cornea, aqueous humor, lens, and vitreous humor
Anterior segment of the eyeball is occupied by aqueous humor
Anterior chamber of the eye is the space between the cornea anteriorly and the iris/pupil posteriorly
Posterior chamber of the eye is between the iris/pupil anteriorly and the lens and ciliary body posteriorly
Lens is posterior to the iris, anterior to the vitreous body, and is a transparent, biconvex structure enclosed in a capsule
Capsule of the lens is highly elastic and anchored by zonular fibers (collectively constitutes the suspensory ligament of the lens)

Ciliary Muscle and Accommodation

Ciliary muscle changes the shape of the lens
Accommodation is the process of changing the lens shape
Ciliary muscle contraction reduces the tension on the zonular fibers, allowing the lens to become more convex

Supporting Apparatus of the Eyeball

Fascial sheath of the eyeball envelops the eyeball and extends posteriorly from the conjunctival fornices to the optic nerve
Medial and lateral check ligaments limit abduction and adduction
Suspensory ligament of the eyeball consists of check ligaments and oblique muscles
Inferior check ligament forms from the fascial sheath of the inferior rectus

Nerves of the Orbit

Optic nerves (CN II) convey purely sensory nerve fibers transmitting impulses generated by optical stimuli
Optic nerves begin at the lamina cribrosa of the sclera and are surrounded by extensions of cranial meninges and subarachnoid space
Oculomotor (CN III), Trochlear (CN IV), and Abducens (CN VI) nerves supply ocular muscles
Ophthalmic nerve (CN V1) supplies structures of the anterior orbit (lacrimal gland and eyelids), face, and scalp

Vasculature of the Orbit

Ophthalmic artery is the main blood supply of the orbit
Infra-orbital artery contributes blood to structures of the orbital floor
Central retinal artery arises inferior to the optic nerve and supplies the retina
Choriocapillaris supplies the external aspect of the retina
6 short posterior ciliary arteries directly supply the choroid and nourish the outer nonvascular layer of the retina
2 long posterior ciliary arteries anastomose with the anterior ciliary arteries to supply the ciliary plexus

Veins of the Orbit

Superior and inferior ophthalmic veins pass through the superior orbital fissure and enter the cavernous sinus
Central retinal vein usually enters the cavernous sinus directly
Vorticose veins drain into the inferior ophthalmic vein
Scleral venous sinus (canal of Schlemm) is a vascular structure encircling the anterior chamber of the eyeball

Lacrimal Apparatus

Consists of: lacrimal gland, excretory ducts of lacrimal gland, lacrimal canaliculi, and nasolacrimal duct
Lacrimal gland secretes lacrimal fluid – watery physiological saline containing lysozyme, a bactericidal enzyme
Lacrimal fluid moistens and lubricates surfaces of conjunctiva and cornea, provides nutrients and dissolved oxygen to the cornea

Extraocular Muscles

4 recti muscles: Superior rectus, Inferior rectus, Medial rectus, and Lateral rectus
2 obliques: Superior oblique and Inferior oblique
Levator palpebrae superioris elevates the superior eyelid

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Description

Test your knowledge on extraocular muscles, blood vessels, nerves, eyeball, and lacrimal apparatus. Learn about the anatomy and functions of the levator palpebrae superioris, recti muscles, and oblique muscles in the eye.

Extraocular Muscles and Eye Structures Quiz

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