I played tennis throughout high school and college and prided myself on developing a little muscle bulge in each forearm, near the elbow, that my brother dubbed “the egg.” He has one in each forearm, too. With a little help from my friend the Trail Guide to the Body, I now believe I can properly identify “the egg” as the extensor carpi radialis longus. Let’s dive into a little anatomy lesson, and from there we’ll also consider some problems that can arise within the forearm and the elbow.

The forearm contains various muscles responsible for creating movement at the wrist and fingers, and the crowded muscle bellies and tendons can be challenging to isolate. So how do I know which one is my egg? Well, when I want to show off my egg, I bend my elbow, kink my wrist to the thumb side of my hand, and also bend at the wrist to bring the back of my hand closer to the hairy side of my forearm. The egg appears right near the outside of my elbow crease, just above the bony landmark on the outside of my elbow. In more sophisticated terms, then, my egg must be a muscle on the posterior/lateral surface of the forearm with a potentially large belly situated above the lateral epicondyle of the humerus that contracts upon extension and abduction (radial deviation) of the wrist and may also assist in flexion of the elbow.

Extensors of the forearm, including extensor carpi radialis longus

The extensor carpi radialis longus fits the bill. As the name suggests, this muscle extends the carpals (wrist joint), travels along the radial side of the arm, and is quite long. It originates from the lateral side of the humerus (distal one-third of the lateral supracondylar ridge) and attaches to the base of the second metacarpal bone (metacarpal of the index finger). Together with other extensors of the wrist, the extensor carpi radialis longus stabilizes the wrist during gripping motions, preventing flexion.

So that’s cool….I figured out a name for a specific muscle bulge feature thing in my forearm. The Yoga Tune Up® world has introduced me to how fun it is to know some anatomy and some muscle names. But the real take-away here is that, whether you are interested in the forearm or any other area of the body, once you dive in to learn more by, say, consulting the information and diagrams and pictures provided by a resource like the Trail Guide to the Body, you realize how much is there, how complex it all is, and how amazing the human body is.

The reality check – and what’s not so cool – is that the human body is not immune from injury. Let’s focus back in on the forearm and the elbow. An unfortunately common injury here is lateral epicondylitis, or inflammation of the tendon common to the origin of some of the extensor muscles on the outside of the elbow. Lateral epicondylitis is also known as “tennis elbow.” Ah, tennis. Yet this is an injury that is certainly not limited to tennis players. And while our newly identified extensor carpi radialis longus muscle can be a player in tennis elbow trouble, it is far from the only potential problem child.

In this case, knowing the name for something – tendonitis, or tennis elbow – is not quite so fun or enlightening. The term itself tells us nothing about (i) why you might have problems when another person doesn’t, even when doing the same volume and intensity of activity, or (ii) why you were fine with these same activities a year ago, but now they are creating difficulties.

We’ll revisit this problem of pain and tightness in the elbow next time. Join me then to shed some light on why you may be having elbow problems and to learn some strategies for working through them or perhaps even preventing them from occurring at all.

Liked this article? Read Injury to Innovation

Mandy Pansing

Mandy is a Yoga Tune Up® and Roll Model® Method superfan, so much so that she went ahead and completed certifications in each. She has spent most of her life in school pursuing science and engineering-related degrees while mixing in a variety of extracurricular fun with team sports and individual endurance sports. With this life-long background in academics and athletics, and a continued fascination with the human body, self massage, and healthy movement, Mandy is poised to help endurance junkies and stressed out academics alike experience the benefits of regular self-care and conscious movement practices.

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The trail guide to the body is such a useful tool for body workers and athletes alike! Good on you for getting curious about your body and looking for answers. Knowledge is power.

Beth Prandini

I am studying the forearm right now in The Yoga Tune Up training and I love your “egg” description. Thank you for a great post.

Jean Black

I love how you’re using your newfound knowledge!


Hi Mandy, Id like to hear more about your egg. I don’t have an egg but do have both tennis elbow and golfers elbow. And yes, it does hurt if I play either sport. My extensor carpi radialis longus also gets very angry with me when I grip the handle of the rope for wakeboarding. Unfortunately stopping activities I enjoy is not an option for me, because being in-active is a mental killer. Was wondering if you are using any rolling techniques to alleviate pain. Im finding if I use rolling techniques such as stripping and plowing in the valleys… Read more »

Alyssa P

Super interesting to hear your process for locating the extensor carpi radialis longus muscle in order to further discover the reason for pain & tightness. As a graphic designer with chronic pain in my hands, wrists and forearm – all the way to the elbow joint – this has provided a newfound inspiration to examine these muscles more closely and see what can be done to undo the overuse / misuse in this area.


The title of this blog made me curious! You have written at a nice and informative way. I think this tenniselbow is the same as a Mouse-elbow (the mouse that you use with a computer). This is also a RSI because of repetative strain during over a longer period. Besides calm stretches of the muscles of the fore-arm I do now know that we also can roll this area 😉


I found the egg in my forearm! I use this wrist stabilizer muscle a lot and have never paused to locate it on my body. The extensor carpi radialis longus is a long name and one that I won’t soon forget!

Kelly Cameron

Thank-you for the great article Mandy! Injuries toted as “tennis elbow” were always a grey area as there are so many muscle bellies and connections like you mentioned. Your forearm action description and pictures were very helpful in identifying this muscle (it really does pop out!). Looking forward to reading the next article on strategies! =:0)


Yes, the tennis bulge in the forearm. Getting ready to bulk it up heading into summer tennis league season. Can’t wait to lock this info into the brain and feel it, let me grab my tennis racquet and re-read this!

Haley Bevers

Thanks for sharing all of this….my aunt actually gets tennis elbow from working so much at a computer. I know how a new term to add to my repertoire of anatomy.

Kammy Fung

Thank you for the information. My elbow pain located different from inside of the elbow so it’s more like a golfer’s elbow instead. The information give me a chance to look at my injury a bit closer. The extensor of our hands need a little bit more care for sure. Thanks again, looking forward to your next pose!

Diana Azavedo

Thanks for this informative article. Yes the body is fascinating indeed. It is great to get acquainted with the the extensor carpi radialis longus and its role in stabilizing the wrist during gripping motions, preventing flexion. I am always excited to find the part two of this to understand the tennis elbow even more since this topic has always intrigued me.

kaleen Lugo

So helpful to have an explination for the muscles involved with Tennis elbow. I have been curious about this for years! Thank you

Jennifer M.

This post is a great introduction into how I see I am to approach learning anatomy in a way that is meaningful to me for my body. Your ‘way in’ sets up my curiosity as reader and active participant. It’s making me realize that I stress my elbows and wrists in ways that set my body up for tennis elbow. I already feel my wrist as an extension of my neck from your other post.

And I love how you talk us through finding the ‘egg.’

Your writing is engaging and clear.


Thanks for the easy to understand explanation of tennis elbow – I never really knew exactly what it was or what was happening in the body; now I do!


Great description. I absolutely love rolling this part of the body. Looking forward to part 2 to read about why this area is such a trouble spot for me.

Tracy Wagner

Thanks for the interesting information, I never really knew much about tennis elbow.

Tracy Wagner

I totally know what you mean by exploring more about about our bodies, the YTU course is helping me a great deal. So many awe moments. Thanks for the interesting information.

Tracy Wagner

Although I can’t relate to the tennis elbow it was very interesting to learn something new. I totally know what you mean by exploring more about about our bodies, the YTU course is helping me a great deal. So many awe moments.


Funny and interesting.
I have a few friends play tennis but they never told me about their elbow problems.
maybe they didn’t play so much like you did. but I will share this information with them.
thank you.


I like the vivid description of the location of this muscle and the amazing (and maybe not amazing) ways this muscle works for us!

Catherine RL

Thank you for the wonderful post. Very informative.
I have always wondered what the “egg” was on my arm. It is very noticeable. I have been told by many MDs that I also have tennis elbow and have noticed that when I lift weight bars I often get cramps or pain in the area. Looking forward to your next blog!

Susannah Nelson

Your post made me smile Mandy as I know only too well about eggs in my arms , as a massage therapist these eggs can grow a little too large for my liking , great post discussing the anatomy. I love using original size YTU balls and eccentric loading exercises to keep my connective tissue pliable and not over worked .

Tammy abresch

Love this article !! I play tennis and will use the information you have so willingly shared. Thank you.

Catherine RL

Thank you for the wonderful post. Very informative.
I have always wondered what the “egg” was on my arm. It is very noticeable. I have been told by many MDs that I also have tennis elbow and have noticed that when I lift weight bars I often get cramps or pain in the area. Looking forward to your next blog!

shari Williams

thank you! this was a great exploration. I’ve been working with a client lately with her shoulder & elbow pain. Well, her pain is gone thanks to YTU (R) work I do with her. But now she cannot straighten her elbow. I want to address the elbow specifically and this gave me some ideas to go from. well written

Jasmine Ellemo

As an avid tennis player, you’re catching my attention. I have had tennis elbow in the past and worked very hard to heal it. I look forward to reading your next post!

Michelle W

This is a wonderful post, filled with lots of gems! Diving deep into muscles, their functions, and injuries that may occur there is so valuable. Your post very much felt like an expedition into your own body — and I think it would serve us all to be a little more curious about it, too. Thank you!

Yvonne Cone

Love the start to this thread you’re creating Mandy. I for one have used the term “tendonitis” over the years without knowing what is really happening in the area (any area). I for one did not know that the extensor carpi radialis was so much a part of issues happening in both the wrist and elbow joints. And as someone with a history of carpel tunnel syndrome, that is an awesome piece of information to store in my “Learning more about anatomy” bank.


I’m so glad that you posted this! I too find contentment in using the reference book: Trail Guide to the Body by Andrew Biel to identify muscles and bones, map out my body, and link it to human movement. I’m in awe of how my body serves me everyday. Although I haven’t played tennis, I do go to Crossfit class, and certain repetitive movements can make me prone to developing “tennis elbow” or lateral epicondylitis. In doing farmers carry, pull ups, toes-to-bar, or double unders, or just carrying heavy luggage, I will move more mindfully to not overuse or stress… Read more »