The Conal Space
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We describe the intraconal anatomy and the pathology
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that occurs within that, usually is related to the optic
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nerve and the blood vessels, and the other cranial
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nerves that occur in the intraconal space.
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With respect to conal anatomy,
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we're really talking just about the muscles,
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and there is a very limited amount of pathology that
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involves just the muscles. For the most part,
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we're talking about thyroid eye disease,
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also known as thyroid orbitopathy and pseudotumor,
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or idiopathic orbital inflammation.
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The muscles that we have that are included in the
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conal anatomy are the superior, inferior,
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lateral and medial recti,
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the inferior and superior oblique muscles.
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And these are all connected via a fibrous
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annulus called the annulus of Zinn.
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The conal anatomy includes the rectus muscles.
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These include the inferior rectus muscle,
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the medial rectus muscle and the superior rectus muscle,
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which are innervated by cranial nerve 3.
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The lateral rectus muscle is innervated
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by cranial nerve 6.
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And in addition,
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you have the superior oblique muscle
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and the inferior oblique muscles.
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The superior oblique muscle is innervated
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by cranial nerve 4,
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and you have the levator palpebrae muscle,
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which also is innervated by cranial nerve 3.
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These are seen well on the coronal image.
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The inferior oblique muscle is attaching further
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inferior and posterior to this diagram.
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As you see on the axial scans,
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we're really only seeing the lateral rectus muscle,
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again, innervated by cranial nerve 6, and the medial
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rectus muscle, innervated by cranial nerve 3.
David M Yousem, MD, MBA
Professor of Radiology, Vice Chairman and Associate Dean
Johns Hopkins University
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