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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 (correct)
  • Formed by six bones of the skull
  • Contains three walls and a base
  • Pyramidal-shaped cavity with three sides

    • What structures are contained within the orbital cavities?

  • Only the eyes and their muscles
  • Eyes, muscles, and some fat
  • Eyes, muscles, and lacrimal apparatus
  • Eyes, muscles, nerves, and blood vessels (correct)

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

  • Trauma to the maxillary sinus
  • Fracture of the zygomatic bone
  • Trauma to the ethmoidal & sphenoidal sinus
  • All of the above (correct)

    • 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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