0:00

So let's move down to the elbow.

0:02

Uh, we're gonna talk about the three major branches, um,

0:05

major nerve branches in the elbow, the median nerve.

0:08

Uh, we'll talk about the radial nerve and ulnar nerve.

0:10

So starting first with that median nerve anatomy.

0:13

Again, we wanna use those nice T one sequences to see

0:16

that perineural fat.

0:17

You can see a cosing, uh, kind of a deep in the musculature,

0:21

uh, mostly along the flexor sided, uh, muscles

0:24

and more on the ulnar side of the forearm here.

0:27

And the median nerve gives off one major, uh,

0:30

motor branch that's important.

0:31

The anterior interosseous nerve, it's aptly named, right.

0:34

It runs between kind of the interosseous membrane

0:37

of the forearm and it sits just anterior

0:40

or volar to the interosseous membrane.

0:41

And so you can identify it again by

0:43

that nice perineural fat in that region.

0:46

And the pattern of muscle atrophy that we're looking

0:48

for when we're suspicious

0:50

for a median nerve abnormality really involves those flexor

0:53

muscles of the forearm.

0:55

So the more superficial flexor muscles are predominantly

0:58

innervated by that, uh, that median nerve proper.

1:02

And that anterior an osseous branch tends

1:04

to get the deeper forearm flexors.

1:06

So just keep in mind flexor compartment,

1:08

you're thinking more median nerve abnormality.

1:11

If it's deep, it's probably

1:12

that anterior interosseous branch.

1:14

More superficial, you're thinking a more proximal median,

1:16

uh, nerve abnormality.

1:20

So one of the median nerve entrapments is also known

1:23

as pronator syndrome.

1:24

And pronator syndrome is specifically a repetitive stress

1:28

injury that can cause entrapment of that median nerve.

1:30

And these patients, um, they present

1:32

with a median neuropathy, right?

1:34

And the one we're more familiar

1:36

with median neuropathy is carpal tunnel,

1:37

which we'll talk about later.

1:39

Uh, but the clinical symptomatology can be similar.

1:42

You'll have paresthesias

1:43

or change in nerve function that's really isolated to

1:47

that median nerve distribution of the thumb index long

1:49

and kind of the radial aspect of that ring finger as well.

1:53

Additionally, these patients will have forearm

1:55

symptomatology, which kind of clues you in

1:57

that the problem might be more proximal

1:59

and not so much in the region of the carpal tunnel.

2:02

Um, but there are other clinical symptomatologies

2:04

that can mimic, uh, median entrapment, uh,

2:07

things like even cervical radiculopathy

2:09

or brachial plexopathy.

2:11

Um, this is where imaging can really help play a role.

2:16

So a case of pronator syndrome

2:18

or suspected pronator syndrome.

2:19

This was a 52-year-old man.

2:21

He presented with those carpal tunnel like syndrome, uh,

2:24

symptoms, but he also had

2:25

that forearm weakness and some atrophy.

2:28

And these are two axial stir sequences.

2:30

And again, these imaging findings can be subtle,

2:32

so you really have to window pretty aggressively, uh,

2:35

to detect some signal abnormality in these instances.

2:38

And in this case, the muscle signal abnormality pretty

2:40

subtle, but I think it's there.

2:42

Uh, we have some abnormality of that pronator caries muscle.

2:45

The flexor carpi radis.

2:47

And this pattern, along with the clinical history is pretty

2:50

concerning for pronator syndrome.

2:52

Uh, again, the primary nerve abnormality wasn't really there

2:55

in this instance, but just given the pattern of denervation

2:58

as along with the clinical history,

3:00

we can be pretty confident that this patient has abnormality

3:02

of that median nerve.