Anterior Elbow Case

I did some self scanning today, I had access to a medium-to-high res scanner today and wanted to test some elbow. Anterior elbow is pretty fascinating and high yield if you're interested. There are a lot of great structures within close proximity worth identifying. Also, the anatomy is pretty tricky to understand from a textbook. A good scan, however, makes the relationships very vivid.

As a resource, I used ESSR's Anterior Elbow guide. I found it to be the perfect level of detail. Jacobsen is my gold standard, but is unwieldy when bedside.

First off ,what can you see here:

• Brachialis tendon 
• Coronoid recess
• Articular cartilage of distal humeral
• Brachialis muscle
• Anterior fat pad
• Humeral capitellum
• Humeral trochlea
• Posterior Interosseous nerve (radial)
• Cutaneous sensory branch (radial nerve) 
• Median Nerve
• Brachial Artery
• Brachioradialis muscle
• Radial head / neck
• Superficial / Deep head of the supinator muscle

I took some screen shots of the highlights:

Anterior distal humerus epiphysis

I love the distinguished wave of this bony structure. Note the well defined hyaline cartilage overlying the bone. Finally, above this, is the brachialis muscle (with septum / tendon?) down middle. Remember, many muscles have septums. Many also have tendons that start in the belly of the muscle. I think this is tendon. You'll also note brachial artery (large circular hypechoic structure). Median nerve is to the right, though tougher to identify. 

I wanted to trace the brachialis muscle down to its insertion at the coronoid process of the ulna (pinky side for simple thinkers like me). I failed. The muscle belly seemingly disappeared into a mess of pronator teres. I'll try again later.

Radial Nerve Split into posterior interosseus + cutaneous sensory branch

I'm proud of this one. It takes a keen eye and good understanding of the anatomy. The radial head is exceedingly easy to find early on: it's the only nerve spiraling around the tricepital area. It's decent sized as well. As we track down the radial (thumb / lateral) side, we hit a branch point around the head of the radius. See Page 4 for a fantastic diagram 

Here the radial nerve splits into posterior interosseus nerve and cutaneous sensory branch of the radial nerve. This is the first tip off: you will see a split. It's fairly subtle. The next big clue is what I've captured below: the posterior interosseus nerve going through the supinator muscle (Arcade of Frohse).

Below you can see the hypoechoic radial head. Overlying this is a muscle circumferentially surrounding the head with a very bright body bisecting the muscle. This is the radial nerve bisecting the supinator muscle.

Yellow = posterior interosseus nerve
Orange = supinator
Blue = Radius