Muscles that move the eyes

Muscles that Move the Eyes

Extrinsic Eye Muscles

  • Definition: Muscles responsible for eye movement, allowing coordinated tracking of objects.

  • Importance: Ensure accurate visual perception; coordinating eye movements is crucial for effective vision.

Types of Extrinsic Eye Muscles

  • Six main extrinsic eye muscles control eye movements:

    1. Lateral Rectus Muscle: Moves the eye outward, away from the nose.

    2. Medial Rectus Muscle: Moves the eye inward, toward the nose.

    3. Superior Rectus Muscle: Elevates the eye, moving it upward.

    4. Inferior Rectus Muscle: Depresses the eye, moving it downward.

    5. Superior Oblique Muscle: Rotates the eye downward and away from the nose.

    6. Inferior Oblique Muscle: Rotates the eye upward and away from the nose.

Innervation of Extrinsic Eye Muscles

  • Innervated by three cranial nerves:

    • Oculomotor Nerve (Cranial Nerve III): Controls most extrinsic muscles.

    • Trochlear Nerve (Cranial Nerve IV): Innervates the superior oblique muscle.

    • Abducens Nerve (Cranial Nerve VI): Innervates the lateral rectus muscle.

Coordinated Eye Movements

  • Essential for binocular vision, depth perception, and visual tracking.

  • Conjugate eye movement: When both eyes move together harmoniously.

  • Disruptions can lead to diplopia (double vision) and focusing difficulties.

Convergence and Divergence

  • Convergence: Both eyes move inward to focus on near objects (e.g., reading).

  • Divergence: Both eyes move outward to focus on distant objects.

Eye Movement Abnormalities and Disorders

  • Various conditions can affect eye functioning:

    • Strabismus: Condition where eyes misalign (crossed eyes), leading to potential double vision.

    • Nystagmus: Involuntary, repetitive eye movements, often linked to neurological disorders.

Role in Rapid Eye Movements (REM)

  • Extraocular muscles are active during REM sleep, involving rapid eye movements linked to dreaming.

Clinical Evaluation of Eye Muscles

  • Finger tracking test: Checks coordination of eye muscles for abnormalities.

  • Diagnostic techniques include:

    • Hirschberg Test: Light source checks eye alignment.

    • Cover Test: Assesses eye muscle disorders via occlusion.

Eye Movement Training

  • Exercises and vision therapy can improve eye coordination and strengthen eye muscles for individuals with control difficulties.

  • Understanding these muscles aids in perceiving and interacting with the world.

Detailed Diagram of Eye Muscles

  • Illustrates the arrangement and connections of extrinsic eye muscles.

Comprehensive Overview of Key Extrinsic Eye Muscles

Muscle

Movement Description

Target Direction

Prime Mover

Origin

Insertion

Superior Rectus

Moves eyes up and inward (elevates and adducts)

Medial

Superior rectus

Common tendinous ring (optic foramen)

Superior surface of the eyeball

Inferior Rectus

Moves eyes down and inward (depresses and adducts)

Medial

Inferior rectus

Common tendinous ring (optic foramen)

Inferior surface of the eyeball

Lateral Rectus

Moves eyes outward (abducts)

Lateral

Lateral rectus

Common tendinous ring (optic foramen)

Lateral surface of the eyeball

Medial Rectus

Moves eyes inward (adducts)

Medial

Medial rectus

Common tendinous ring (optic foramen)

Medial surface of the eyeball

Superior Oblique

Rotates eyes downward and outward (depresses)

Lateral

Superior oblique

Sphenoid bone

Surface of eyeball between inferior and lateral rectus

Inferior Oblique

Rotates eyes upward and outward (elevates)

Lateral

Inferior oblique

Floor of orbit (maxilla)

Surface of eyeball between inferior and lateral rectus

Levator Palpebrae Superioris

Raises upper eyelid

Upper eyelid

Levator palpebrae

Roof of orbit (sphenoid bone)

Skin of upper eyelids

Orbicularis Oculi

Closes eyelids

Eyelid

Orbicularis oculi

Medial bones of orbit

Circumference of orbit

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