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Let's begin our discussion of tendon anatomy, starting

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with the gastroc anemia, soleus continuation

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as the achilles tendon, the achilles tendon.

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And these two constituents are one of the structures that

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produces plantar flex.

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I'm listing some of the other ones here.

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So what is this particular tendon?

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Well, here's a beautiful picture, uh, taken

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by Michael Stadnik, a drawing that he did that shows you,

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in fact, what the achilles tendon is.

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The myo tendons unit

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of the Achilles tendon spans three joints.

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Remember, it spans the knee, the ankle, and the sub joint.

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It represents a continuation, okay,

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of the aosis on the anterior surface of the gastroc

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and the posterior surface of the sous muscle.

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So the tendon forms where they join right here,

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and it extends down to the attachment

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on the postal superior aspect of the calcaneus.

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The literature would tell you that in general, 10

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to 15 centimeters in limp, there is, there is an area

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of tenuous vascularity.

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There's a debate about it,

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but in general it occurs two to six centimeters

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above the level of the calcan attachment.

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We'll talk more about sites of tendon tearing in a moment.

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There is no sheep.

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There is a perin rather than a tend sheet.

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So we do talk about peritonitis more about that term later.

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We do not talk about 10 synovitis,

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and it in fact, uh, will occupy

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and have to absorb major loads during, uh, uh,

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of the body weight here, 12.5 times body weight

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that's placed on the tendon

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during certain activities such as running.

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Now, I wanted to give you an idea of, of

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what these two constituents, gastro and sous do.

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This is a view of the back of the, uh,

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lower leg showing you here, the gastrocnemius muscle

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in yellow, the sous hidden in front

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of the gastrocnemius in red.

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If we did a cross section right here,

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this is what it would look like.

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The amount of sous versus gastroc

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contribution varies, but classically, of course the soleus

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is located here more anteriorly.

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The gastroc is located more posteriorly.

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But as we move down, there is a rotation so lower down.

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As you look at this, you can appreciate that the gastroc

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component is located laterally

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and the soleus component is located medially

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of variable size

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As I'm showing here.

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And that is why as you look at your axial images,

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as you proceed from the top to the bottom,

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you can see in fact the sous contribution

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extending from a lateral to medial direction

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as it joins the gastro uh, contribution.

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And it does produce a slight convexity

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to the anter surface of the tendon.

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I know we're told to look for that convexity

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'cause it's generally indicates pathology,

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but this is the normal focal convexity that occurs

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where the sous joins the gastroc

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to form the achilles tendon.

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And it's of interest as you look at it, you can see

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the attachments of these various components to the

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calt tuberosity, like every tuberosity that I know about.

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It is not smooth. The tuberosity has facets.

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This is the area of the superior facet kind

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of superolateral that's intimate

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with the retrocalcaneal bur, I'll talk more about

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that in a little while.

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As we go to the medial

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or middle facet, we can see medially as we would expect.

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Then the soleus attachment

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and laterally, you can see here the lateral

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head of the gastroc.

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And then below that in the inferior facet, the medial head

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of the gastroc anemia attaches.

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So just like we talked about earlier, uh,

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mini talked about the greater trocanter

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and the facets related to the gluteal tendon.

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All of these tuberosities have facets.

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And this is the anatomy at the site of attachment

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of the calcaneus.

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Now adjacent to the achilles tendon,

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we have the longest tendon in the human body.

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This is the planned terrace tendon

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that starts at the lateral aspect of the, of the knee

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and extends all the way down to the ankle, generally

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attaching to the calcaneus,

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although occasionally to the achilles tendon.

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These are three particular patterns in which you can see the

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attachment of the plantars tendon here

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to the calcaneus here to the achilles tendon.

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This is what it looks like in a, in sagittal images,

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there are reports that if the plantar tendon is thickened,

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if it has tendonosis, there may be a higher risk

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for abnormalities in the adjacent portion

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of the achilles tendon.

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Now, let's look normal sagittal section

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of the achilles tendon attachment.

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Here's a sagittal Mr.

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And I wanna point out

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that normally we have a pre Achilles fat pad

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that sends a sliver

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Of fat just behind the postal superior aspect

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of the calcaneus.

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That when you look at this with conventional radiography

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or as shown here with Mr Imaging, you will see

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that sliver of fat.

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I call this the retro cal calcan recess.

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On a lateral radiograph,

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you see a triangular radiolucent shadow on an mr.

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You see fat signal between the achilles tendon

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and the postal superior surface of the calcaneus.

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Sitting in this area is a bursa, a normal bursa that goes

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by the name of the retro calcan bursa.

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The images on the left represent

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the situation in a cadaver

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where we have injected air into the bursa and distended it

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and then sectioned in a sagittal way.

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That particular region showing you

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that when you distend the bursa, that particular sliver

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of fat is displaced superiorly away from the back

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of the calcaneus.

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Here is kind of what it would look like. Diagrammatically.

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Here is what retro calcan bursitis looks like

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with reactive edema in the calcaneus tendinosis,

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superficial bursitis as well.

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So this is retro calcaneal bursitis.

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There are a number of accessory muscles.

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I'm not gonna be able to cover all of them.

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I will cover a few during this lecture.

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This is the accessory sous muscle, typically superficial

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to the flexor ret macular.

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In most of the cases, not all it attaches

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to the calcaneus shown here.

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The sous muscle, in some cases

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extends further down than the level

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of the ankle joint shown here.

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This is a low lying sous insertion, right,

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but the main fong finding the accessory sous muscle.