0:00

The posterior tibial tendon.

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This provides quite a bit of medial

0:05

support to the plantar arch of the foot.

0:07

I'm not going to talk so much about origins

0:09

today, but we are interested in insertions,

0:12

since we're focusing on the foot and ankle, and

0:16

the insertion of this structure is legendary.

0:19

The best way to memorize it

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is it inserts on everything.

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The navicular, the cuneiforms, the

0:25

cuboid, the metatarsals, there's

0:28

even a recurrent calcaneal band.

0:31

But the most important insertion

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is to the navicular.

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It's important to note that the navicular

0:37

can have innumerable configurations.

0:40

It can be a smooth, round structure.

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There can be an accessory bone inside

0:46

the posterior tibial tendon, which

0:48

is known as an os tibiale externum.

0:50

There can be a hook-shaped or corniculate navicular,

0:54

to which the posterior tibial tendon attaches.

0:57

Or there can be a structure with a

0:59

synchondrosis between it and the navicular

1:02

body to which the tendon attaches that

1:06

can lead to an os navicular syndrome and

1:10

irritation of the posterior tibial tendon.

1:12

Now, as the tendon comes down in a

1:15

neutral position, it arcs a little bit.

1:18

So it is prone to get a little bit grayer as it

1:21

curves, and this is known as magic angle effect.

1:25

It'll always look blacker on T2-weighted

1:27

imaging even with fat suppression.

1:31

The tears that occur in this tendon

1:32

tend to be retro and inframalleolar.

1:35

They are very rarely at the insertion

1:38

unless you have an anomaly such as

1:41

an os tibiale synchondrosis or one of

1:43

these variants of the navicular.

1:46

Now, when you're trying to categorize

1:48

the posterior tibial tendon, I like to

1:52

divide it up into myotendinous junction

1:55

and muscular area, then supramalleolar,

1:59

retromalleolar, inframalleolar, belly, and

2:05

insertion, which is going to be fan-shaped.

2:07

So let's go to the axial projection.

2:09

Here are our friends, Tom,

2:11

here's Dick, here's Harry.

2:14

Now don't get confused, because

2:15

there's a lot of other dots here.

2:17

There are vessels, and nerves, and veins,

2:19

which we'll discuss a little bit later.

2:22

But just underneath the posterior tibial tendon is

2:26

the deltoid, and as we get a little more distal,

2:29

underneath it is the superior calcaneonavicular

2:32

ligament, also known as the spring ligament.

2:35

So these two structures together help support

2:38

the arch of the foot and prevent pes planus.

2:43

Over top of the posterior tibial

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tendon is the flexor retinaculum,

2:48

also known as the laciniate ligament.

2:50

Now let's follow the tendon.

2:52

Let's go up a little higher.

2:54

So now we're supramalleolar.

2:56

Now let's get a little retromalleolar.

2:58

It may flatten out a little bit.

3:00

Now let's get inframalleolar.

3:01

It becomes a little more elliptical or elongated.

3:04

And now let's watch as it

3:06

inserts on the navicular.

3:08

There it is.

3:09

And there comes the fan.

3:12

The fan-shaped other bundles that are

3:14

going off every which way to virtually

3:17

every other bony structure in the foot.

3:22

Those are of lesser importance to us than the

3:24

ones that insert directly on the navicular.

3:28

That is our summary of the

3:31

posterior tibial tendon anatomy.