0:00

This vignette is focused on the

0:03

biceps and its reflection pulley.

0:06

The biceps takes off on high,

0:08

so let's go up higher to its origin.

0:11

You can see that it has a fairly broad area of takeoff.

0:16

This one is pretty far anterior, but it can take

0:18

off in the back or in the middle of the glenoid.

0:21

So quite a bit of variability, and it has an intimate

0:26

takeoff from the superior tubercle of the glenoid.

0:29

So, the biceps, when it's injured, may injure

0:33

the superior tubercle of the glenoid, or the

0:36

fibrocartilaginous lip associated with it.

0:39

And this is weaved into the discussion of SLAP lesions,

0:42

which we're not here to discuss at this moment.

0:45

So the biceps has this arcuate component.

0:48

It is secured by several structures, including

0:52

the anterior coracohumeral ligament,

0:54

as we'll see in the sagittal projection.

0:56

And the superior glenohumeral ligament,

0:58

as we'll see in the sagittal projection.

1:02

As we scroll and work our way down,

1:05

the biceps is secured in the bicipital groove.

1:07

And at this location, it's extra-articular,

1:10

but it is surrounded by synovium.

1:12

So it has a synovial sheath.

1:14

When it's inside the joint, when it's intra-

1:16

articular, especially this arcuate segment, which

1:19

is not infrequently injured and this injury is

1:21

frequently missed, it is not surrounded by synovium,

1:24

so it's intra-articular. Yet, extra-synovial.

1:28

And this is a little bit confusing.

1:30

So as we work our way down, we pay attention to the

1:32

shape and configuration of the bicipital groove.

1:35

And we see that there is a structure that

1:37

secures the biceps, the coracohumeral ligament.

1:39

This is just one component of the biceps reflection pulley.

1:43

And there is a lateral component

1:45

onto the greater tuberosity.

1:47

There's a medial component onto the lesser tuberosity.

1:49

And if you look very carefully, there's a component

1:52

that reflects underneath the biceps as well.

1:57

Further contributing to the security

2:00

of the biceps is the subscapularis.

2:02

I think you can see that a little better right here.

2:05

And we'll see it better in some other cases.

2:07

The superficial fibers of the subscapularis may

2:10

cross over with the coracohumeral ligament or

2:13

transverse ligament of the biceps and has a few

2:16

fibers that insert on the greater tuberosity.

2:20

Now let's turn our attention to the

2:22

sagittal projection for a moment.

2:24

And I'm going to take you right to the glenoids.

2:27

So once you get to the glenoid, first of all, here

2:29

are structures going straight back from the coracoid.

2:32

There's two of them right there.

2:34

And these are known as the intra-articular superior

2:38

components of the CHL, coracohumeral ligament.

2:42

Now, the extra-articular portion of the

2:45

coracohumeral ligament, which is right there,

2:47

forms the roof of the rotator interval and

2:52

helps secure the biceps and the glenoid.

2:53

Pulley complex.

2:55

Now let's find our biceps.

2:56

There's our biceps right there.

2:57

There it is.

2:58

There it is.

2:59

There it is.

3:00

Now let's follow it back out.

3:01

So now we're at the glenoid cup.

3:03

The so-called pear-shaped glenoid cup.

3:05

Now work our way, work our way lateral

3:08

from the pear-shaped glenoid cup.

3:10

There's our biceps.

3:12

And what's on top of it?

3:14

The SGHL.

3:16

The superior glenohumeral ligament.

3:17

Now watch what happens.

3:19

It merges with the CHL.

3:23

And you can start to see them separate down below.

3:25

So we got CHL.

3:26

And SGHL, we'll keep going, and now this is SGHL

3:31

forming the bottom of this pulley mechanism.

3:34

And the CHL forming the anterior wall of this pulley

3:38

mechanism, or the anterior wall of the rotator interval.

3:41

What's the interval?

3:42

The interval is the space between the anterior margin of the

3:45

supraspinatus and the superior margin of the subscapularis.

3:49

That is not the only interval.

3:51

There's going to be an interval between

3:52

the supraspinatus and infraspinatus.

3:55

And between the infraspinatus and teres.

3:57

But we're not interested in that right now.

3:58

We're interested in the anterior interval.

4:01

Let's keep following it out.

4:03

And as we do, we kind of lose it into the subscapularis.

4:07

The further out you are, the more the SGHL forms

4:11

the underbelly, the floor of the trampoline, of the

4:15

biceps pulley reflection mechanism, containing the

4:18

biceps, with the CHL as the anterior boundary of it.

4:23

This one filled with fluid.