0:00

Well, let's move now

0:02

to our flexor tendon anatomy complex here as well,

0:06

of course, because we know we have two components,

0:09

the flexor digitorum superficialis, as well

0:12

as the flexor digitorum profundus, the profundus passing

0:15

through an aperture or opening in the superficialis

0:19

and they kind of trade positions.

0:22

Here's what that aperture looks like when we're looking at

0:26

that tendon one passing through the other.

0:30

And let's take a look at the imaging proximally.

0:33

You can see the position or relationship of profundus

0:36

and superfic more distally where they swap positions

0:40

and even more distally as we move towards the distal aspect

0:45

and the DIP articulation.

0:48

Other components of anatomy that you should be aware of

0:52

with respect to the flexor tendon is the cullet tendon.

0:57

Now, when we consider these structures,

0:59

they're thread like bands of synovial membrane,

1:03

and they help to offer nutrition to the relatively avascular

1:08

structure of the tendon, kind of attaching it

1:10

or anchoring it down to the flexor tendon sheath.

1:13

These little arrowhead pointing

1:15

to these really delicate structures

1:18

that extend from the flexor digitor profundus

1:21

to the superficial and ultimately to the tendon sheath.

1:25

And if you've seen either contrast in a tendon sheath,

1:30

probably less likely, or distension of a tendon sheath

1:32

because of fluid, um, synovial hypertrophy inflammation,

1:37

sometimes you'll be these threads of low signal intensity

1:40

or even areas of hypertrophy,

1:42

and that can represent thickening of these vin tendon.

1:46

So just be aware that those structures are present.

1:50

We have zonal anatomy in the flexor tendon complex

1:54

as well here looking at the palmar aspect

1:57

of the articulation.

1:59

Again, I don't necessarily recommend

2:01

that you use zonal references when you're talking about

2:04

tendon abnormalities,

2:06

but realize that some

2:07

of your referring orthopedic hand surgeons will clearly use

2:11

this zal reference.

2:13

And as you think about all of the pathology

2:16

that we can encounter in various different zones,

2:19

you've probably seen all of this

2:22

here in the sagittal illustration looking at,

2:26

in a detailed fashion, both the pulley system as well

2:30

as the flexor tendon complex

2:33

from proximal to distal.

2:35

And so you have that mapped out

2:38

for you on these illustrations.

2:42

Flexor tendon injuries are not as common as injuries

2:44

to the extensor tendon.

2:46

They're a little bit deeper classified as open

2:49

or closed, partial or complete.

2:52

The most common is an open injury

2:54

associated with a laceration.

2:55

You can imagine that grabbing a structure and having those

2:59

Flexor tendons lacerated,

3:01

usually they're involving the mid substance of the tendon.

3:04

And you can imagine, again, that

3:05

because of that grasping phenomenon,

3:07

and once again, we're going to look at in the setting of,

3:11

uh, a laceration to very carefully describe the points

3:14

of failure, the degrees of retraction, where the torn ends

3:19

of the tendon lie

3:20

and associated findings that would include geno synovitis,

3:23

pulley disruption, or other soft tissue abnormalities.

3:28

And so as you consider that zonal abnormality here,

3:31

looking in the sagittal imaging, plain failure in this case

3:35

of vector digitor, superficial LS

3:37

and profundus, you want to describe the torn ends

3:41

of both components.

3:43

Again, using o osteos anatomic reference standards

3:47

and so that you can be very specific.

3:49

So the surgeon knows when they go to fish around

3:51

for the torn ends of the tendon, how far proximal they need

3:54

to look and how far distal they need to look.

3:57

That becomes, of course, very, um, important.

4:00

And as you look in the coronal imaging plane

4:02

that undulating sort of noodle like appearance

4:06

of the tendon, um,

4:07

very characteristic when you've got a lacerated

4:10

or completely torn tendon looking at the margins

4:13

of the tear, also help you to identify the acuity.

4:17

You can see that the soft tissue defect in a lot

4:20

of these open lacerations completely closes up and you may

4:23

or may not see the tilt tile sign of little focal, um,

4:27

points of low signal intensity to represent gas.

4:30

Um, but that very, very narrow zone

4:34

of transition at the site of failure, suggestive

4:36

of an acute laceration.

4:38

Whereas more chronic tendinosis, of course,

4:42

may have frayed ends of the tendon or irregular ends.

4:47

Closed flexor tendon injuries include emulsion of the FDS

4:51

and FDP uls of the FDP is more common

4:55

and caused by a sudden hyperextension during active flexion.

4:59

Four types have been described with refraction to the palm,

5:03

to the PI pite to avulsion of an osseous fragment

5:06

or simultaneous avulsion

5:08

of the FDP from a fracture fragment here.

5:12

Just showing that

5:14

and referring to the distal end being in that zone one,

5:18

of course the proximal end coming down here to zone two.

5:21

And we would specifically identify the points, uh,

5:25

with respect to maybe you would say the proximal third

5:28

of the proximal phalanx to give a very accurate, um,

5:32

anatomic reference point

5:34

for the torn proximal component of that tendon.

5:39

Another example here, type two retraction

5:41

to the PIP in this case, really

5:44

to the distal tooth thirds junction with

5:47

or rather proximal two thirds distal, one third of

5:49

that proximal phx being very specific with respect to where

5:53

that torn of tendon comes to.

5:59

Let's move now. Closing in on the last few topics

6:02

of our time together.

6:04

Um, this, the intrinsic muscles of the hand.

6:08

And this is, um, one of those topics with respect

6:12

to anatomy, illustrations

6:14

and development that I was very motivated to look at

6:17

because every time I would see abnormalities in these areas,

6:22

I would always have to go back

6:23

and take a look at the anatomy to try to figure out exactly

6:26

what I was looking at.

6:27

And so this, um, is a, uh, an excellent, I think,

6:31

illustration to really

6:33

summarize this intrinsic muscles at the hand.

6:36

We're gonna focus in detail on the lumbrical.

6:39

That will be the next topic that we look at,

6:42

but I wanted you to also have a reference

6:44

for the interosseous muscles as well as thenar eminence

6:48

and the hypoth thenar eminence.

6:51

These are mapped out for you here

6:54

with specifics describing them with respect

6:57

to mid hand thinner and hypo or eminence.

7:00

And hopefully you will find this useful to you

7:02

as you leave this course

7:04

and perhaps have hand imaging where you're dealing

7:06

with abnormalities in these specific muscles

7:09

and have a nice reference to look at.