Subscapularis Anatomy and Pathology
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We're back to our often ignored,
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but never forgotten axial section.
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Evaluating it for the rotator cuff.
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Yes, it's important for the labrum,
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but that's a story for another day.
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And here is our big, fat, whopping subscapularis.
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The subscapularis has a tendon.
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In fact, it's got at least four, sometimes
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five, separate tendons from caudate to cranial.
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And they make kind of like a fan.
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And when you're evaluating whether it's an
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interstitial tear or a full-thickness tear,
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you want to describe whether it involves the
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upper segment, middle segment, or lower segment.
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You can divide the segments up into fourths or
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fifths, I don't really care, as long as you convey the
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proper message and the proper context to the surgeon.
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Now although not apparent at this particular slice,
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Bear in mind that the subscapularis inserts on the
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lesser tuberosity a little higher up than this,
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but underneath it will be the middle glenohumeral
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ligament which inserts on the middle tuberosity.
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We're below that, but that's okay.
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You can envision it.
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And then the subscapularis also sends some fibers
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over the top a little higher to contribute to the
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transverse ligament to help secure the biceps.
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The major contributor to the transverse
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ligament is the coracohumeral ligament.
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Another important structure that it's going to
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insert in the neighborhood, although we can't
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appreciate it on this particular slice, but you
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should be aware of it, is the pectoralis major
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tendon, also known as the falciform ligament.
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And it'll come in right about here as a very thin
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structure, And it can tear here at the insertion, back
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at the myotendinous junction, or back in the muscle.
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And that's a pretty important piece of information to
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convey, and that will be a subject we'll cover separately.
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But for now, I'm most interested in the subscapularis,
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the way it has a fairly broad insertion, I'll make it
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pink, broad insertion on the lesser tuberosity, sits
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right over the middle glenohumeral ligament, and Has
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individual segments as you climb from caudate to cranial.
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Has a very scant contribution to the transverse ligament.
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But can be a very symptomatic structure even when partially
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torn because of its contribution to rotatory movement.
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Something as simple as writing may be
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irritating to somebody with a subscap tear.
Stephen J Pomeranz, MD
Chief Medical Officer, ProScan Imaging. Founder, MRI Online
ProScan Imaging
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