Orbit and Contents
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Orbit and Contents

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@FelicitousCognition

Questions and Answers

Which of the following best describes the boundaries of the orbit?

Boundaries formed by seven bones, with four walls, an apex, and a base

What structures are contained within the orbital cavities?

Eyes, muscles, nerves, and blood vessels

Which type of trauma may cause damage to the frontal lobe of the brain?

All of the above

Which nerve innervates the Ciliary muscle and Sphincter pupillae?

<p>Oculomotor nerve (CN III)</p> Signup and view all the answers

Where are the preganglionic parasympathetic nerve cell bodies found for the innervation of the Ciliary muscle and Sphincter pupillae?

<p>Edinger-Westphal nucleus</p> Signup and view all the answers

Which muscle is innervated by the sympathetic system to cause dilation of the pupil?

<p>Dilator pupillae</p> Signup and view all the answers

What manifestation is a result of a lesion to the cervical sympathetic trunk, leading to Horner's Syndrome?

<p>Drooping of the upper eyelid (ptosis)</p> Signup and view all the answers

Which nerve is responsible for the movement of the lateral rectus muscle in the eye?

<p>Abducens nerve (CN VI)</p> Signup and view all the answers

What is the main function of the Dilator pupillae muscle?

<p>Dilation of the pupil</p> Signup and view all the answers

Which structure do the postganglionic sympathetic fibers join before reaching the iris to innervate the Dilator pupillae muscle?

<p>Superior cervical ganglion</p> Signup and view all the answers

Where are the preganglionic sympathetic nerve cell bodies located for the innervation of the Dilator pupillae muscle?

<p>Spinal cord T1</p> Signup and view all the answers

Which structure is responsible for changing the shape of the lens to focus on near objects?

<p>Ciliary muscle</p> Signup and view all the answers

What is responsible for producing and secreting tears?

<p>Lacrimal apparatus</p> Signup and view all the answers

The orbit contains several openings, including the optic canal. What structures pass through the optic canal?

<p>Optic nerve and ophthalmic artery</p> Signup and view all the answers

Which muscle is responsible for closing the eyelid?

<p>Orbicularis oculi muscle</p> Signup and view all the answers

How many layers does the eyeball have?

<p>Three</p> Signup and view all the answers

Which nerve controls the ciliary muscle within the ciliary body?

<p>Oculomotor nerve</p> Signup and view all the answers

What is responsible for keeping the upper eyelid elevated?

<p>Superior tarsal muscle</p> Signup and view all the answers

Where are the extraocular muscles located?

<p>Between the eye and the orbit</p> Signup and view all the answers

How many sets of muscles does the iris have?

<p>Two</p> Signup and view all the answers

What is responsible for elicit movement of the eye?

<p>Extraocular muscles</p> Signup and view all the answers

Which opening in the orbit allows passage of oculomotor nerve, trochlear nerve, abducens nerve, and branches of ophthalmic division of trigeminal nerve?

<p>Superior orbital fissure</p> Signup and view all the answers

Which nerve transmits visual information from the eye to the brain?

<p>Optic nerve</p> Signup and view all the answers

Which artery supplies blood to the eyeball and orbit structures?

<p>Ophthalmic artery</p> Signup and view all the answers

Which muscles are the only ones acting in the X-axis and are important for clinical testing?

<p>Medial and lateral rectus</p> Signup and view all the answers

What is the mnemonic for the innervation of extraocular muscles?

<p>LR6 SO4 AO3</p> Signup and view all the answers

Which muscles must be isolated for clinical testing by aligning muscle pull with the gaze of the orbit?

<p>Superior rectus and Inferior oblique</p> Signup and view all the answers

What is the function of the Ophthalmic division of Trigeminal nerve?

<p>Provide sensation to the eyeball and surrounding area</p> Signup and view all the answers

Which veins drain blood from the orbit and eye?

<p>Superior ophthalmic vein and Inferior ophthalmic vein</p> Signup and view all the answers

What is the function of Trochlear nerve [IV]?

<p>Control movement of the superior oblique muscle</p> Signup and view all the answers

What is the role of Superior rectus muscle?

<p>Elevate the eye (look up) in the Y-axis</p> Signup and view all the answers

Which nerve innervates the extraocular muscles and the eye?

<p>Oculomotor nerve [III]</p> Signup and view all the answers

Which of the following boundaries is matched to its respective bone?

<p>Apex: Optic canal</p> Signup and view all the answers

Match each opening of the orbit to its contents

<p>Optic Canal = Optic nerve (CN II) and ophthalmic artery Superior Orbital Fissure = Ophthalmic vein, oculomotor nerve (CN III), trochlear nerve (CN IV), abducens nerve (CN VI), branches of the ophthalmic division of the trigeminal nerve (CN V) Inferior Orbital Fissure = Maxillary division of the trigeminal nerve (V), zygomatic nerve, infraorbital artery and vein N/A = N/A</p> Signup and view all the answers

Match each layer of the eyeball to its contents

<p>Outer Fibrous Tunic = Sclera, Cornea Middle Vascular Tunic = Choroid, Ciliary body, Iris Inner Layer = Retina Other = Aqueous humor, Lens, Vitreous body</p> Signup and view all the answers

Match each muscle of the orbit to its actions

<p>Ciliary Muscle = Flattens the lens for distant vision, and increases the curvature of the lens for near vision. Sphincter Pupillae = Pupillary constriction. Innervated by postganglionic parasympatheric fibers Dilator Pupillae = Pupillary dilation. Innervated by postganglionic sympathetic fibers N/A = N/A</p> Signup and view all the answers

Match each nerve palsy to its appropriate description

<p>Oculomotor nerve palsy = Ptosis, dilated and nonreactive pupil, fully abducted and depressed pupil Trochlear nerve palsy = Dipoplia when looking down Abducens nerve palsy = Affected eye is adducted due to unopposed action of the medial rectus muscle N/A = N/A</p> Signup and view all the answers

Which nerve is paired with the muscle(s) it innervates?

<p>Trochlear: Superior oblique muscles</p> Signup and view all the answers

Ophthalmic artery is a branch off of which artery?

<p>Internal carotid artery</p> Signup and view all the answers

Occlusion of which of the following arteries of the eye leads to blindness?

<p>Central artery</p> Signup and view all the answers

Study Notes

  • Trochlea and six extraocular muscles: Levator palpebrae superioris, Superior oblique, Superior rectus, Medial rectus, Inferior oblique, and Inferior rectus
  • Medial and lateral rectus are the only muscles acting in the X-axis, important for clinical testing
  • Superior and inferior rectus, oblique muscles, are the only muscles that elevate the eye (look up) in the Y-axis
  • Superior rectus and inferior oblique muscles must be isolated for clinical testing by aligning muscle pull with the gaze of the orbit
  • Superior oblique and inferior rectus muscles are the only muscles that depress the eye (look down) in the Y-axis
  • Innervation of extraocular muscles: LR6 SO4 AO3 (mnemonic)
  • Optic nerve, a sensory nerve, transmits visual information from the eye to the brain
  • Ophthalmic division of Trigeminal nerve, a sensory nerve, provides sensation to the eyeball and surrounding area
  • Motor nerves, Oculomotor [III], Trochlear [IV], Abducens [VI], innervate the extraocular muscles and the eye
  • Ophthalmic artery, a branch of the internal carotid artery, supplies blood to the eyeball and orbit structures
  • Two venous channels, superior and inferior ophthalmic veins, drain blood from the orbit and eye.

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Description

Test your knowledge of the anatomy and functions of the extraocular muscles with this quiz. Identify the muscles and understand their roles in eye movement.

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