The Anatomy of Thoracic Outlet Syndrome: The Anterior Scalene Muscle is the Key to TOS

Join Dr. Scott Werden for the most recent in his "The Anatomy of Thoracic Outlet Syndrome" series as he discusses The Anterior Scalene Muscle and why it is the key to understanding TOS. Live participant Q & A.
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Understanding anatomy is the key to understanding TOS
Abnormal anatomy causes or contributes to compression of the vital structures in the thoracic outlet. As a result, patients experience the symptoms of TOS. While the anatomy of the thoracic outlet is complex, understanding the anatomy enables understanding of TOS. We can strive to understand the structures that cause compression as well as the structures that become compressed.
We can categorize the essential anatomy into these categories:
Anatomy of the spine
Anatomy of a nerve
Anatomy of the brachial plexus
Anatomy of the thoracic outlet
Anatomy of the spine
The spine supports our body weight while allowing flexibility in multiple directions.
The vertebral body is the basic building block of the spine. Vertebral bodies (also known as vertebrae) are stacked one upon the other from the skull to the pelvis. The vertebral bodies support our body weight.
Between each vertebral body lies an intervertebral disc. Each disc is firmly attached to the vertebral body above it and to the body below it. The disc has a fibrous outer layer that stabilizes each vertebral body to the next. The center of each disc contains a jelly-like substance that absorbs impacts from walking, jumping and other movement. The flexible discs allow movement in multiple directions:
Flexion and extension: Forward and backward bending
Lateral bending: Side to side bending
Rotation: Side to side twisting
Vertebral bodies and intervertebral discs
The spine comprises five anatomic regions, from top to bottom:
Cervical spine: The neck
Thoracic spine: The mid-back; twelve paired ribs arise from the thoracic spine, forming the rib cage
Lumbar spine: The low back
Sacral spine: The base of the spine; joins the pelvis to the spine
Coccyx: The tailbone; in humans, the coccyx represents a vestigial tail
Spine anatomy regions
Each region of the spine has a different number of vertebral bodies:
Cervical spine-seven segments, numbered C1 (‘Cervical’ 1) through C7
Thoracic spine-twelve segments, numbered T1 (‘Thoracic’ 1) through T12; each body has a rib on each side
Lumbar spine-five segments, numbered L1 (‘Lumbar’ 1) through L5
Sacral spine-five segments, numbered S1 (‘Sacral’ 1) through S5; these segments are fused together into one bone in adults, which articulates with the pelvis on each side.
Coccyx-three to five segments, with variable degrees of fusion in the adult; usually referred to as a single unit rather than separate vertebrae.
A bony arch arises from the back of each vertebral body. These arches line up to form a flexible bony tunnel, the spinal canal. The spinal canal runs from the base of the skull to the pelvis, and it contains and protects the spinal cord. At each spinal level, a nerve leaves the spinal cord on each side. Each nerve exits the spinal canal through a tunnel between the bony arches to reach the body or extremities. This tunnel is called a neural foramen.
On the back and sides of each arch, bony protrusions arise, which allow for attachments of the numerous muscles that stabilize and move the spine.

[@MoonSoar]

Thank you for the detail. I'm learning and figuring out how I want to navigate bilateral TOS.

[@eazthitman]

Many thanks for this highly detailed explanation of TOS. I have had pins and needles in my ring and pinky fingers and occasionally my other three fingers. I have it both sides but worse on my left. It keeps me awake almost every night. I had a nerve test and the doctor diagnosed carpal tunnel and I was offered surgery. This does not make sense to me since my main symptoms in my ring and pinky fingers relate to the ulnar nerve. After studying TOS for a week of so I now strongly suspect TOS is my problem. I have been following exercises relating to TOS and have seen much improvement over the past week or so. I am so grateful for videos such as this and many others for helping us look after ourselves and make the right choices.

[@tosmri]

Thank you for the nice comments. It certainly sounds like you may be right to suspect TOS. Some patients who are originally diagnosed with CTS do, in fact, have TOS. Contact us and we can help you figure out how to pursue the right diagnosis. www.tosmri.com/contact-us/

[@Scott36744]

I really love this video ❤

[@tosmri]

Thank you very much!

[@homeiswherewepitchit4994]

This was by far the best info I have seen! Thank you! Maybe I missed it, but is there a specific MRI that will show the compression of the Brachial plexus? During shoulder surgery, if a thickened coracoacromial ligament is released can this cause the shoulder to roll forward and end up becoming TOS? Is the pectoralis muscle ever involved with TOS?

[@tosmri]

Thank you for your compliments and question. Yes, the NeoVista® study does show compression of the brachial plexus on dynamic arm positioning. As to your second question, there is no literature I am aware of showing imaging of the thoracic outlet prior to and following release of the coracoacromial ligament. I suspect there would not be a significant change, however, since that ligament does not contribute to the static position of the clavicle or scapula.

[@janekim3946]

Dr Werden! Thank you so much for what you are doing! Your passion and dedication help lots of patients with TOS including me. I learned so much from your channel.

[@tosmri]

Sorry for the late response. Really appreciate your support!

[@msCindyZ]

@@tosmri I 😢am at my wits end This is at a point of intolerance this chronic pain. Can I be seen?

[@megancolasono1108]

I wrote a longer description of my TOS and experiences with it. Sharing our stories always seem to help others get a proper diagnosis! Dr. Werden, I have noticed that when my one of my trapezius muscles get swollen and hard, the knots and pain extend up the neck and into the head causing migraines. Rarely I can use my massage gun to release the muscle and get relief. But 99% of the time I have to take a migraine medication, Imatrex. Why would a migration medication work to relieve this flair up of tightness and mostly pain? Post op I was at a point where at home migraine injections stopped working.

[@tosmri]

Hi again, Megan. We don't answer specific medical questions here for obvious reasons. As a radiologist, I do not prescribe medications, so this question is better to ask of your primary care doc or a pain management doc. I hope that is helpful.

[@doctorshutup9817]

Great info here doc and I really liked the Q and A format. Out of curiosity, are you familiar with MSK neurology here on youtube (he also has his own site) and I've gleaned a lot of helpful info from him. For instance, one issue brought up by a lot of your viewers was difficulties with diaphragm breathing. I experienced this as well and one aspect that I think may be being overlooked is an adaption of swayback posture in TOS patients causing a gripping effect in the lower abs and inhibiting the diaphragm. I corrected this issue via physical therapy exercises and just wanted to share it with you and your audience. Anyway just wanted to say thanks and ask you about what you think about MSK neurology and his methods. He has a great article about it on his website in my opinion. Thank you.

[@tosmri]

Yes, I am familiar and have read posts. Thank you for sharing the info about breathing and core musculature. We appreciate patients who 'pay it forward' to help others!

[@doctorshutup9817]

My pleasure. If I may, do you have any recommendations as far as TOS specialists in the chicago area?

[@tosmri]

@@doctorshutup9817 Although I have not worked directly with him, you could look up Dr. Jason Ko in Chicago.

[@NomiaCoffee]

Thank you for the walk through.. I am curious to understand the dynamic In N-TOS…what would be the nerve compression resulting in the Tinnitus?. For me while the arm numbness was mildly annoying it was the 24/7 Tinnitus for a year that almost drove me mad.. thanks

[@tosmri]

Thank you for the excellent question. There is no direct nerve involvement causing tinnitus. Many authorities believe that there is a disturbance in venous blood flow in the head and neck that can cause headache, brain fog, and tinnitus, among other symptoms.

[@1ashlybruc1]

I had a c7 fracture with a whiplash injury and also eventually developed tinnitus. I would love to get resolution of mine as well.

[@megancolasono1108]

I have Bi-lateral TOS. I have always thought my case would be a good one to add to a study. My surgeon is considered one of the top 5 in the U.S that specialize in this surgery, Dr. Gregory Pearl. I had my left side surgery first and then 8 months later my right side. In the thousands of cases he has done, I had two things he had never seen before. Both of my Anterior Scalene muscles were literally ROCK HARD! Dr. Pearl noted that he had never seen one let alone both anterior scalene muscles as hard as a rock. The second thing he had not seen until my case. Was the large fibrous bands that filled my pectoral or chest area. He removed all of the banded tissue. He as well removed both first ribs along with the connected anterior scalene muscles. My TOS is three fold in that it is genetic, as my Mom has right sided TOS. She had a rib resection done in the early 90s.This is when they only removed a small section of the first rib. Her chronic pain was only alleviated by a smaller percentage than is possible today, with full rib removal. Second I suffered from 4 or 5 events of severe whiplash. 3 were car accidents and 2 other more severe neck injury. Third I was a hairstylist for 17 years, until my TOS caused me to be disabled as it went undiagnosed for so long. I also have the unfortunate, rolled forward shoulders, forward set head, and that posture. What I find odd is that genetically my Mom has diagnosed right sides TOS. But my Father has the very obvious rolled forward shoulders and forward set head. Massage therapists were always shocked and confused when my shoulders would be so high up, “around my ears,” they would describe. And then they would both drop a few inches after the massage. I have not been able to meet and receive care from a Primary Care Doctor in the Houston TX area. I have had to retain my Primary Doctor in Seattle while I live in Texas due to each doctor denying to take me on as a patient. They each said they had never met anyone with TOS, had only read about it in text books, or had never heard of it before. Even the pharmacists here don’t believe in this “rare” disorder causing the kind of level 10 chronic pain that we suffer.

[@tosmri]

Thank you for sharing your story. You have definitely had a lot of injuries that could contribute to or cause TOS. There are a couple of papers in the literature that describe the microscopic changes of the scalene muscles after trauma. These show a lot of fibrous tissue replaces muscle cells, and that the type of muscle cells changes. Glad to hear you are doing better after all these challenges!

[@yasqueen9092]

Thank you, I watched this because I have bilateral paresthesia symptoms and that emulate cubital tunnel syndrome and medial nerve entrapment as well. My nerves flare up mostly while typing on the computer and when I lay on my back or push my back to the back of a chair, it's so weird. Mostly it translates as shocks in my fingers, I hate them so much I've grown to be stressed and afraid to do many things. Seems like everything is coming from the braquial plexus and I don't know what to do :( it's been six months and I've gotten better but seems like I've hit a wall. No typing for me yet so I can't work. Oh, also, smoking Marihuana is like taking 3 steps back in progress for me, I stopped because of this, gave it a try today again after not smoking for about 2 months and my symptoms are back like they were a month ago. Crazy! I'm curious to know what that is about as well.

[@NomiaCoffee]

My unproven theory re: your cannabis comment is that it is not actually causing the symptoms to be worse.. but it’s that the cannabis is opening up expanded awareness and consciousness of what’s happening in your body… (basically we become more tuned in and sensitive to whats happening physically and mentally with our bodies) and that results in us perceiving an elevation in X,Y,Z going on in our bodies.. although cannabis can act as a muscle relaxant my understanding is that will only go so far and when there is a mechanical impingement involved.. that will not be solved by muscle relaxants alone.. good luck 🤞

[@tosmri]

Sorry to hear you are struggling with this. Have you seen a true TOS specialist? We can help you find one: www.tosmri.com/thoracic-outlet-syndrome-education/contact-us/

[@viewernum72]

your comment is helpful to me

[@JDMintegraVTEC]

I would be very interested to hear input on scoliosis and these types of syndromes. I have a 40 degree thoracic S curve that really goes up high into the cervical spine.

[@JDMintegraVTEC]

I've also broken my left clavicle 4 times, and had an ac joint surgery

[@tosmri]

@@JDMintegraVTEC Hi, Liam. This is not a great place for personal medical advice. Here are some general thoughts. Scoliosis can certainly affect the positions of the shoulders, which can lead to narrowing of the spaces of the thoracic outlet. Advanced imaging such as CT and MRI can help with this. Clavicle fractures may heal with a large bony callus. Depending on the size and location of this callus, there could well be narrowing and compression on the brachial plexus. Please reach out to us at www.tosmri.com/thoracic-outlet-syndrome-education/contact-us/

[@alfredsamkutty4191]

Hi doctor Werden, in this talk you mentioned a musician who wore a vest for his TOS symptoms. Is there anywhere I could find out more about this vest? Thanks.

[@tosmri]

Yes, its through Dr. Tracy Newkirk. Please contact us and we will connect you with Dr. Newkirk www.tosmri.com/thoracic-outlet-syndrome-education/contact-us/

[@msCindyZ]

I’m a TOS Survivor so far I am having and always had had a problem with my hyoid bone. I have had my first rib removed, left side, diagnosed bilateral, and have been a TOS person for 22 years now I recently had my disk replacement C4 C5, with six eyes still am in chronic pain and I’m watching your interior scalene thoracic outlet and I live in California I had seen a neurologist here in California named Dr. Agnew and he retired in my health has gone down since then I have also, do you have driven to Northern California to see Dr. Ellis for injections I’m currently in physical therapy it’s not much help. I have Medicare so I have a limited PT

[@tosmri]

Hi, @mscindynicholson We are glad to help. This isn't a good forum for that purpose. Please contact us at www.tosmri.com.

[@cathyleblanc4347]

Do you know if squeezing of the muscle in the neck causing Thunderclap headaches..thank you so much

[@tosmri]

In general, there is no association between TOS and thunderclap headaches. However, TOS patients frequently note headaches in general as part of their symptomatology.

[@cathyleblanc4347]

Thank you..I have been diagnosed with Ntos.. Getting results of MRA tomorrow.For 5+ years I have been trying to figure this out..But with knowledge there's hope..Thank you so much.

[@AlondraCarranza-kf6pc]

👌💘🤙

[@1ashlybruc1]

After many years of thoracic outlet symptoms, I have gradually also developed some lymphatic issues and venous hypertension/ varicose veins. How closely related is restriction of the lymphatic duct at the collarbone to TOS and can restriction of the venous system here cause backup elsewhere in the body?

[@tosmri]

The lymphatic system is very low-pressure, and most of the lymphatic system empties into the thoracic duct in the left supraclavicular fossa. This can be compressed, leading to edema. But elevated venous pressure in the left subclavian vein may also limit lymphatic drainage.