Bones of the Orbital Region
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Questions and Answers

Which of the following bones is NOT part of the bony orbit?

  • Lacrimal Bone
  • Maxillary Bone
  • Frontal Bone
  • Occipital Bone (correct)

    • What is the primary function of the extraocular muscles in the orbital region?

  • To move and position the eyeball within the orbit (correct)
  • To control the amount of light that enters the eye
  • To lubricate the eye
  • To protect the eye from external injury

    • What is the main function of the bony orbit?

  • To protect the eye from external injury and trauma (correct)
  • To lubricate the eye
  • To regulate the amount of light that enters the eye
  • To control the movement of the eyeball

    • Which of the following is NOT a soft tissue of the orbital region?

    <p>Sphenoid Bone</p> Signup and view all the answers

    What is the main function of the conjunctiva in the orbital region?

    <p>To lubricate the eye</p> Signup and view all the answers

    What is the overall function of the orbital region?

    <p>To support and facilitate the functions of the eye</p> Signup and view all the answers

    What is the location of the lymph vessels and nodes in the orbital cavity?

    <p>No lymph vessels or nodes are present</p> Signup and view all the answers

    How many voluntary muscles are involved in the movement of the eyeball?

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

    What is the term used to describe the rotation of the eye upward?

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

    What is the role of the inferior oblique muscle in eye movement?

    <p>It assists the superior rectus muscle to raise the cornea directly upward</p> Signup and view all the answers

    What is the point of reference used to describe the rotatory movements of the eyeball?

    <p>The upper rim of the cornea</p> Signup and view all the answers

    Through which structure do the inferior ophthalmic vein and pterygoid venous plexus communicate?

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

    Through which structure does the tendon of the superior oblique muscle pass?

    <p>A fibrous pulley attached to the frontal bone</p> Signup and view all the answers

    In which direction does the tendon of the superior oblique muscle turn after passing through the trochlea?

    <p>Backward and laterally</p> Signup and view all the answers

    What is the purpose of the medial and lateral check ligaments?

    <p>To attach the tendon sheaths to the medial and lateral walls of the orbit</p> Signup and view all the answers

    What is the function of the fascial sheath of the eyeball?

    <p>To provide a socket for free movement of the eyeball</p> Signup and view all the answers

    Which muscles do not take part in the movement of the eyeball?

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

    What is the orientation of the origins of the superior and inferior recti muscles relative to their insertions?

    <p>About 23° medial to their insertions</p> Signup and view all the answers

    Which nerve supplies the sphincter pupillae?

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

    Where do the postganglionic fibers of the sphincter pupillae synapse?

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

    What is the function of the dilator pupillae?

    <p>To dilate the pupil in low light intensity</p> Signup and view all the answers

    What is the purpose of the macula lutea?

    <p>To enable most distinct vision</p> Signup and view all the answers

    What is the outer layer of the retina in contact with?

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

    What is the anterior part of the retina composed of?

    <p>Pigment cells and columnar epithelium</p> Signup and view all the answers

    What is the function of the hyaloid artery in the fetus?

    <p>To fill the hyaloid canal</p> Signup and view all the answers

    What is the role of the vitreous body?

    <p>To support the posterior surface of the lens</p> Signup and view all the answers

    What is the shape of the lens?

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

    What attaches the lens to the ciliary processes?

    <p>The suspensory ligament</p> Signup and view all the answers

    What is the function of the suspensory ligament?

    <p>To attach the lens to the ciliary processes</p> Signup and view all the answers

    What is the result of the pull of the radiating fibers of the suspensory ligament?

    <p>The lens becomes flattened</p> Signup and view all the answers

    Study Notes

    Fetal Development and the Eye Structure

    • The hyaloid canal connects the optic disc to the lens's posterior surface in fetuses, filled by the hyaloid artery which regresses before birth.
    • The vitreous body slightly enhances the eye's magnification, supports the lens, and holds the retina against the pigmented layer.

    The Lens

    • The lens is transparent, biconvex, and encapsulated, located behind the iris and in front of the vitreous body.
    • Comprised of an elastic capsule, anterior cuboidal epithelium, and lens fibers from the equatorial epithelium; these fibers form the lens's bulk.
    • The lens capsule's tension causes a preference for a globular shape, essential for focusing.
    • The lens equator connects to ciliary processes via the suspensory ligament, which influences its shape for distance vision.

    Extraocular Muscles and Eye Movements

    • Superior and inferior recti originate about 23° medial to insertions, enabling optimal elevation or depression of the cornea.
    • Testing involves lateral eye movement to assess the actions of the recti and oblique muscles.
    • Intrinsic muscles, including the ciliary muscle, constrictor, and dilator pupillae, do not move the eyeball but control pupil size.

    Fascial Sheath of the Eyeball

    • The fascial sheath surrounds the eyeball, separating it from orbital fat and allowing free movement.
    • Medial and lateral check ligaments attach sheath for the medial and lateral recti to the orbital walls.

    Bones of the Orbital Region

    • Composed of frontal, zygomatic, maxillary, ethmoid, lacrimal, palatine, and sphenoid bones, forming a protective bony orbit.
    • Extraocular muscles like the recti and obliques control eyeball movement within the orbit.

    Functions of the Orbital Region

    • Protects the eye, supports and moves the eyeball, controls light entry, and maintains lubrication.
    • The inferior ophthalmic vein connects to the pterygoid venous plexus, facilitating drainage into the cavernous sinus.
    • No lymph vessels or nodes are present within the orbital cavity.

    Eye Movement Terminology

    • Eye movements include elevation (upward), depression (downward), abduction (laterally), and adduction (medially).
    • Six voluntary muscles: superior rectus, inferior rectus, medial rectus, lateral rectus, superior oblique, inferior oblique.

    Iris and Pupil Functionality

    • Sphincter pupillae receives parasympathetic innervation from the oculomotor nerve, controlling pupil constriction.
    • Dilator pupillae responds to sympathetic fibers for pupil dilation under low light or stress.

    Nervous Coat: Retina

    • The retina includes an outer pigmented layer and an inner nervous layer, connecting with the choroid and vitreous body.
    • The macula lutea, located in the retina's center, is crucial for sharp vision, while the ora serrata marks the retina's non-receptive anterior edge.

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    Description

    Learn about the bones that form the orbital region, including the frontal, zygomatic, maxillary, and others. Understand their functions and relationships with the eyeball and extraocular muscles.

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