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<v ->Now, tenosynovitis can develop

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in areas where we have tendon intersection.

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And these are most common in the hand and wrist

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and in the foot and ankle region.

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I think everyone, or most people

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who do MRI of the hand and wrist recognize

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the two intersection syndromes

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that occur where tendons cross each other in the wrist.

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The first of these,

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we call the proximal intersection syndrome, it's here.

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And it's where the tendons

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and compartments one and two cross.

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And I've indicated the names of those various tendons

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in the six compartments of the wrist.

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So these cross proximal to the radial carpal compartment.

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And so, unfortunately, sometimes when you program

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your wrist MRI for wrist pain,

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you do not include a site, this proximal,

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and you're gonna miss the example

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of the proximal intersection syndrome,

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here tenosynovitis, where these tendons cross.

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More distally, we have a distal intersection,

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and here we can get distal intersection syndrome.

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Here compartments two and three cross,

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here is the extensor pollicis longus,

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extensor carpis radialis longus and brevis,

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they cross more distally.

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This is far more frequent in my practice

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and this is the proximal intersection syndrome.

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It produces pain and swelling.

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Here's another example of distal intersection syndrome

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showing you tenosynovial fluid,

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the white arrows pointing out the crossing

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of the tendons in the second

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and third extensor compartments.

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Now there are areas in the ankle and foot

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where tendons cross and they go by the name of a Chiasma.

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And there are two Chiasma that are present

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in the ankle and foot.

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The first one gets very little press.

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This is the Chiasma Crulale.

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It occurs proximal to the ankle joint.

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It occurs where the tibialis posterior tendon

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and the flexor digitorum longus tendon cross.

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And here you can see what it looks like.

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Here you can see as the tibialis posterior tendon moves

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to the more medial location it crosses.

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And although the literature would tell you

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there's no particular friction that develops here,

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we have seen a number of cases where the tenosynovial fluid

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about those two tendons dominates

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in the area of the Chiasma Crurale.

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So be aware of that.

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That is an area where tendons cross.

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More distally we end up with a Chiasma Plantare.

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You may know it as the Master Knot of Henry.

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Here we have Dick and Harry that are crossing.

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Dick crosses more superficial, more planter than Harry.

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And by the way, there are slips that extend

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between those two tendons, one or more slips.

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This is a very complex area because you see

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we have the quadratus plantae you in the same area.

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So we have all kinds of crossings.

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So going here, it looks like railroad tracks are right,

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that we're looking at.

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It is common to get fluid

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in the area of the Master Knot of Henry.

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And most of the time fluid

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in this location is not symptomatic

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but if it's outta proportion to fluid elsewhere

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it may be symptomatic.

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So keep that in mind

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you could be dealing with tenosynovitis.