Extraocular Movement


Extraocular Movement, Oculomotor Nerve Structure, Conjugate Gaze, Pontine Paramedian Reticular Formation, Lateral Gaze Center, Paraabducens Nucleus, Medial Longitudinal Fasciculus, Ophthalmoplegia, Ocular Motility, Ocular Motility Disorder (SMQ)

  • Definitions
  1. Conjugate Gaze
    1. Movement of both eyes in the same direction at the same time
  2. Ophthalmoplegia
    1. Weakness or paralysis of one or more Extraocular Movement Muscles
    2. Results from either a Muscle disoder or nerve palsy
  • Anatomy
  • Innervation
  1. Cerebral Cortex
    1. Voluntary Conjugate Gaze (Brodmann's Area 8)
    2. Involuntary Conjugate Gaze (Areas 17-19)
  2. Cranial Nerves
    1. CN 3 (nucleus in Midbrain)
    2. CN 4 (nucleus in Midbrain)
    3. CN 6 (nucleus in pons)
  3. Nucleii and Pathways
    1. Lateral Gaze Center (Pontine Paramedian Reticular Formation, Paraabducens Nucleus)
      1. Responsible for horizontal gaze and saccade eye movements
      2. Facilitates Conjugate Gaze by synapsing with contralateral fibers for coordinated eye movements
    2. Medial Longitudinal Fasciculus (MLF)
      1. Transmits signals between CN 3 and CN 6 to coordinate eye movements (Conjugate Gaze)
      2. Dysfunctional in Internuclear Ophthalmoplegia (e.g. Multiple Sclerosis, esp. if bilateral)
      3. Example of normal Conjugate Gaze pathway via Medial Longitudinal Fasciculus
        1. Cortical signal from voluntary gaze center directs left eye to look left
        2. Left eye CN 6 (lateral rectus) fires for the left eye to look left
        3. CN 6 signals Synapse with the Lateral Gaze Center
        4. Signals are transmitted via Medial Longitudinal Fasciculus across midline to contralateral CN 3
        5. Medial rectus directs the right eye to also look left (adduct to look medially)
  • Anatomy
  • Extraocular Muscles: Innervated by CN 3 with 2 exceptions
  1. Medial Range of Motion
    1. Medial Rectus (Cranial Nerve III)
  2. Lateral Range of Motion
    1. Lateral Rectus (Cranial Nerve VI)
  3. Upward Range of Motion
    1. Superior Rectus (Cranial Nerve III)
    2. Inferior Oblique (Cranial Nerve III)
  4. Downward Range of Motion
    1. Inferior Rectus (Cranial Nerve III)
    2. Superior Oblique (Cranial Nerve IV)
  • Anatomy
  • Images
  1. See Neurologic Anatomy of the Eye
  2. eye_eom.png
  3. eyeOculomotorGrayBB785.gif Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  4. eyeOculomotorGrayBB889.gif Lewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  • Pathophysiology
  • References
  1. Goldberg (2014) Clinical Neuroanatomy, Medmaster, p. 40-53
  2. Netter (1997) Atlas Human Anatomy, ICON Learning, p. 114, 126