Serratus Anterior Muscle Origin, Insertion, Function

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Published: June 29, 2016
Last reviewed: August 4, 2017

What is serratus anterior?

Serratus anterior is a muscle that runs from the side of the rib cage to the front surface of the scapula on each side.

Serratus anterior word origin: from the Latin serrare = to saw (referring to its shape); anterior = on the front of the body

Synonyms: big swing muscle, boxer’s muscle, serratus magnus

Origin

Serratus anterior originates on the anterior surfaces of the first 8 or 9 ribs on both sides of the rib cage (Video 1) [1].

Insertion

Serratus anterior inserts on the anterior surface of the medial border of the scapula [1].

Serratus anterior muscle

Picture 1. Serratus anterior muscle origins and insertion

Actions

Actions on the scapula: Serratus anterior holds the scapula close to the rib cage and thus stabilizes it. During a forward movement of the upper arm, like during a boxing punch, it abducts (moves laterally, away from the spine) and protracts it (brings it forward). It also rotates the scapula upwards while abducting an arm or lifting weight over the head [1].

Serratus anterior actions

Picture 2. Serratus anterior actions

Actions on the ribs: Serratus anterior lifts the ribs during inhalation [1].

Indirect action on the upper arm: Serratus anterior helps to push your arms forward (pushing an object, making a boxing punch, push-ups or bench presses) and raising your arms forward (anteriorly), sideways (laterally) and backward (posteriorly) (Video 1) [1].


Video 1. Serratus anterior origin, insertion and actions (2.38 min)

Innervation

Serratus anterior is innervated by the long thoracic nerve, which is a branch of the brachial plexus; the nerve fibers arise from the spinal roots C5-C7 [2]. The nerve travels vertically down from the armpit along the middle axillary line. The nerve can be damaged by a direct hit to the side of the chest or during surgical removal of the lymph nodes in the armpit — this results in a winged scapula (the medial border of the scapula sticking out).

Bursae

Bursa is a fluid-filled sac that prevents the friction between the muscles or between the muscles and bones or joints. Serratus anterior lies under the subscapularis muscle from which it is separated by the subscapularis (supraserratus) bursa. It is separated from the ribs by the scapulothoracic (infraserratus) bursa.

Related anatomy: shoulder muscles

Serratus Anterior Muscle Pain Syndrome

Causes

Arm swinging during sprints, running, swimming, weightlifting, tennis, push-ups, chin-ups, repeated lifting of heavy objects with the extended arms, hyperventilation or prolonged hard cough can cause myofascial pain in the serratus anterior muscles.

Symptoms and Signs

  • Pain between and below the shoulder blades, on one or both sides of the chest, especially below the armpits [4] (Picture 3)
  • Sharp pain on one or both sides of the chest triggered by deep breathing, coughing, twisting your upper body or lifting the arms
  • Tenderness below the armpits; applying pressure on the muscle knots that act as trigger points at the level of the 5th to 7th rib can trigger pain that can radiate down the inner side of the arm down to the 4th and 5th finger
  • Difficulty reaching behind the back or above the head

Treatment

Mild serratus anterior pain should improve within several days of avoiding the activities that caused the pain.

Note that serratus anterior pain is usually caused by a repeated overuse and not by an actual injury, such as muscle strain, pull or tear. This means that while the rest from the causing activities can help, stretching exercises, unlike in injuries, may also help relieve the pain.

A physiotherapist may find muscle knots or taut bands at the side of the chest below the armpit, cool the area with a vapocoolant spray (to decrease tenderness) and apply pressure on them and eventually release them (myofascial pain release technique) [5]. A simple massage probably does not work. Dry needling, acupuncture and injections of local anesthetics or steroids may also help relieve the pain [5].

Serratus Anterior Muscle Pain image

Picture 3. Serratus anterior muscle pain distribution

Differential Diagnosis

Other conditions that can cause pain on the side of the chest, below the shoulder blade or down the inner side of the arm:

  • Side stitch
  • Trapped wind
  • Pleurisy
  • Contusion or rib fracture after a fall or blunt trauma
  • Kidney disease (pain in the middle back at the bottom of rib cage)
  • Enlarged spleen or other cause of spleen pain (on the left side)
  • Gallbladder disease (on the right side)
  • Shingles (with or without rash)
  • Coronary heart disease (pain behind the breastbone, in the left shoulder blade and arm)
  • Adhesions after abdominal surgery
  • Thoracic outlet syndrome (a compression of the brachial plexus)
  • Pneumothorax or adhesions in the pleural cavity after its treatment by pleurodesis

Exercises

Stretching Exercises

Stretching exercises are intended to relieve myofascial pain in the serratus anterior.

An example of a stretching exercise [3-p.23]: Sit and reach backward with your arm and shoulder on the affected side. Then reach back with your unaffected arm and grab the affected arm at the elbow and pull to assist the stretch. Repeat several times at the time few times a day.

Wall presses. Stand facing a wall, arm’s distance length from it and place the hands on it at the shoulder height. Push your upper body toward the wall without bending the elbows and then go back to the original position (Video 2).


Video 2. Wall presses (1.04 min)

Strengthening Exercises

Strengthening exercises are intended to increase the strength of the serratus anterior muscles in sports, like swimming or tennis, and to reduce the risk of injuries. Examples:

  • Push-ups
  • Plank with only your toes and forearms touching the floor
  • While lying on the back, lift your arms with the hands pointing toward the ceiling and then reach even further up using your shoulder blade muscles (later you can use dumbbells to increase resistance)
  • Punching a boxing bag
  • Pulling a rope

34 Responses to Serratus Anterior Muscle Origin, Insertion, Function

  1. Barbara Stein says:

    Last week I had some errands to run with my 4 mo grandson. He is 15 lbs and in an infant car seat. I repeatedly removed the car seat from the base (it’s in the middle seat belt) by holding the front and back of seat and lifting the seat over the sides of the base (so, elbows out and lifting away and toward me). That afternoon I had pain in my side, behind the breast in my chest and side. I watch the baby every day, so I can’t really avoid lifting him, but I have avoided lifting the car seat. Is this likely just a pulled muscle? It’s been a week and it is still extraordinarily painful.

    • Jan Modric says:

      Such pain can be from the serratus anterior overuse and it could last for a week and can be quite sharp. Lifting heavy things with extended arms does not necessary result in pulled, but irritated, muscle. You may want to avoid lifting things for some days and see if the pain subsides.

      I can’t exclude other causes. Broken rib or herniated disc in the spine could also cause such pain.

  2. Jim says:

    About ten years ago I was doing barbell rows while laying on my stomach on a bench and felt some soft tissue in the middle of my back sort of “slide” as I was coming back up from full extension. I believe I maybe tore something but it was never properly diagnosed and being young I came back to sports too soon and although it has improved, it has haunted me for ten years now. It comes and goes but at its worst it is very tight between the shoulder blades on one side, just as shown here. Sometimes I can feel it vaguely under the arm. I am 99% sure it is the serratus anterior causing me trouble. I’ve found I can self massage the tight spot in the back with a lacrosse ball and it is very painful but will loosen up for a short time. It doesn’t seem to fix anything. I am still fit and active and consider myself fairly strong but I can’t seem to get rid of this problem. Is there anything I can do to help it or is it too late and I’m stuck with it!”?

    • Jan Modric says:

      If the tight spot is a muscle knot, then the same exercises that have resulted in a knot will further aggravate it.

      If the tight spot is torn and improperly healed muscle tendon, then I’m not sure if you can do anything about it on your own. You may want to visit an orthopedist to get an exact diagnosis.

  3. Mark says:

    Hi Jan,
    One year ago I was struck by a vehicle on my bicycle (it didn’t seem all that bad at the time). I later developed some pain under my right shoulder blade, exactly where that red dot is on the picture. I’ve been doing physical therapy the whole time. We are trying to figure out how to strengthen the muscles again and make it go away.

    I can feel a tight knot there. I also feel a tingling or “buzzing” sensation, as my therapist says, under my right armpit when I stretch my hands above my head. The back pain goes away temporarily, but it seems to come back during times of stress. I get very fatigued and the pain becomes more prominent, to the point where I just want to give up for the day and sleep it off. I noticed that my neck gets very stiff from time to time.
    A heating pad often times helps loosen things up, but again, it tends to be temporary. I’ve also been trying trigger point therapy with a tennis ball, which hurts like a son of a gun.

    I don’t know where to go from here. I feel like I’m getting close to narrowing it down, but I don’t know the solution. This injury has been bogging me down and I don’t feel “fit” anymore. I’m in my twenties and I don’t want this to continue bothering me.

    • Jan Modric says:

      The muscle knot – the doctor felt it, too? And there is no such knot on the left side?

      Tingling/buzzing speaks for a nerve involvement, possibly the long thoracic nerve. If this nerve is affected, you may (or may not) also have winging scapula (a certain scapula position for which your doctor can tell if it is or not).

      Another set of nerves, called brachial plexus, could be involved – as part of thoracic outlet syndrome.

      Neck stiffness could be from a whiplash injury or from a herniated disc in the cervical spine. In this case you would probably have some pain/tingling in the shoulder or down the arm.

      I suggest you not to overthink this, but if your intuition says to you it could be a neurological issue, you may want to visit a neurologist.

      An injury followed by a local pain and fatigue, strongly suggests post-traumatic stress disorder. This can develop as a psychological reaction to an injury. I see no other explanation, why would a local injury result in general fatigue.

      • Mark says:

        Correct, there is no such knot on the left side and the doctor and myself can feel it. I can see how my fatigue can be PTSD related. I find that I have shallow breathing and anxiety lately.

        What do you recommend as a probable solution?

        • Jan Modric says:

          You may want to discus with your doctor (or a neurologist or orthopedist):
          – Is there any actual muscle weakness that would require strengthening exercises?
          – Is there any abnormality in your shoulder blades alignment that would speak for an organic muscle or nerve damage?
          – Do your symptoms speak for a herniated disc in the neck?

          All of the above can be checked by relatively simple tests during physical examination, but a specialist would probably evaluate this more reliably. I am not trying to suggest you to undergo any expensive investigations, etc. unless a doctor thinks they could help.

          If it comes out that nothing medically can be done, I suggest you to concentrate on what brings peace into your heart rather than on anxiety. Anxiety can be very informative and can tell you that you need to change something, but it is peace, not anxiety, that can guide you.

          Fatigue can come from a long-term stress to which your brain is not able to respond anymore and is kinda giving up. So, maybe there is too much of unnecessary stress (insisting in unpleasant memories, unrealistic ideas or relationships…).

  4. Harpreet Singh says:

    I have the pain on both sides and its been more than a year i have tried several exercises. But still sometimes the pain is triggered even in day to day actvities and it is so acute that i have to let go off what am doing . I don’t know what to do now am afraid of using my muscles for any activity. The pain starts a little below the arm and runs through back to the finger tips and it remains there for atleast 4 -5 minutes .
    Please help

    • Jan Modric says:

      I strongly suggest you to visit a neurologist or orthopedist (ask your primary doctor). The problem may be in the a pinched nerve in the neck part of the spine or inflamed tendons near the elbow, for example.

  5. Jade says:

    I have an achey but sharp pain in and between my shoulder blades, particularly the left. It’s sore and hurts to stretch and is tender to touch. I’ve had back spasms and pain but never like this. I’ve been stretching but it doesn’t seem to help.

    • Jan Modric says:

      Any symptoms in the arms? What could be the cause? Such symptoms could be caused by excessive exercise or bad posture during sitting work, for example.

  6. Wendy says:

    I have pain in my left shoulder blade that extends to my chest, rib cage and below the armpit. The pain started gradually about 5 months ago and got worse about 3 months ago. I have tried using deep heat spray but doesn’t work. Please note I am a nursing mother with 8 months old baby. I had a CS during delivery.

    • Jan Modric says:

      Such pain might result from holding the baby in the same position every time during nursing. If the pain is aggravated by breathing or if there is any tingling or numbness in the arm, I suggest you to visit a doctor.

      • Wendy says:

        Thanks for your response. The pain is not aggravated by breathing but my hand gets cold very quickly on that side, a bit tingly and the whole arm feels tired; not as strong as the other.

        • Jan Modric says:

          In thoracic outlet syndrome, the nerves of the brachial plexus and the blood vessels that run below the clavicle toward the armpit are compressed or stretched. The arm getting cold and tingling speaks for an artery and weakness for a nerve compression. Lifting a stretched arm above the head can trigger or aggravate the symptoms (more than in the other arm). People who have an extra pair of ribs (cervical ribs) are especially prone to have this condition.

          In T4 syndrome or upper thoracic syndrome, frequent twisting of the upper body can irritate the nerves near the thoracic spine and cause pain between the shoulder blades and abnormal sensations in the forearm and hand, usually only on one side.

          Both syndromes are shortly described here, but you can read more about them in other online articles. These syndromes are rare and a primary doctor might not be familiar with them or might not know what to do, so, if your doctor does not find any other cause, I suggest you to ask for a referral to an orthopedist or neurologist.

          I cannot by any means say that this is what you actually have, but you can mention this to your doctor. It does not sound as a simple stretched muscle or tendon to me.

          • Wendy says:

            Many thanks for your detailed response. Cheers

          • Wendy says:

            Hello Jan, I went for chest and Neck x-ray yesterday and the result came out as osteoarthritis of the cervical spine. What drug will you suggest I use? Please note I am an ulcer patient as well. I was asked to buy Diclofenac 50mg and use 3times daily. Thanks

          • Jan Modric says:

            I can’t suggest any drugs here but acetaminophen is similar to NSAIDs and is easier to the stomach. In osteoarthritis, X-ray can show only bone spurs. An MRI can show eventual herniated discs. I’m not saying you should have an MRI, but shoulder pain suggests you may have a herniated disc in the neck. This can often heal on its own with time; it can help if you avoid bending and tilting the head a lot.

    • Moto Mkali says:

      i have these questions for you:
      1. Do you smoke?
      2. Do you exercise?
      3. How is your working/Home environment. Are you standing, sitting, or walking for most of your working?
      4. how id your eating Habits Do you get to eat green vegetables? how many times a week?
      Thanks

  7. Josh says:

    Hi,

    I have pain below and central to my left shoulder blade. It came on suddenly and is still sore however, doesn’t seem to be due to muscle movement (pain isn’t exaggerated with any movement). The pain does however worsen when taking deep breaths. My GP shrugged it off as a muscle strain/pulled muscle but I am worried that it may be more serious as the pain is spreading closer to my spine now. Any suggestions?

    Thanks

    • Jan Modric says:

      In general, if the painful area is tender to touch, the problem is more likely from the chest wall (muscles, bones) and if it is not tender, it can be from an internal organ, for example, due to inflammation of the lung membrane (pleurisy).

  8. Jeanne says:

    I get a very sharp, quick burning pain, like I’m being stabbed with hot poker, kind of tucked in under the outer part of my left shoulder blade.

    • Jan Modric says:

      Such pain usually originate in the muscles or tendons. Arm overuse is a common cause. The pain can go away in a week with relative rest of the upper body.

      • Jeanne says:

        I haven’t really been doing anything, though.

        • Jan Modric says:

          Is the area tender to touch and is it aggravated by the movements of the arms or bending of the neck or trunk?

          • Jeanne says:

            It hits when I am doing nothing. It’s not tender up touch, I have to really push on the area to find ‘the’ spot.

          • Jan Modric says:

            Hm, I don’t know. An orthopedist could tell more after a physical examination.

  9. Mary says:

    I fell with the area under my right arm and the side of my right breast against the front bumper of a Chevy HHR over a week ago and still have at times a sharp pain especially when I cough, sneeze etc

    • Jan Modric says:

      If it’s only a muscle contusion, it should improve in several days/few weeks and if not, it could be a rib fracture or a nerve damage.

      • Nelle says:

        Hi, i can relate to this one. I was diagnosed with asthmatic cough. And now i feel a stabbing pain under the arm and right side of the breast, especially when i cough and stretch. Or even raising my right hand.

  10. Kris says:

    I have a shrill and very sharp 1 – 2 seconds pain one palm length below neck on the left shoulder rear blade. The pain is so acute that for that moment I have to let go any work I am doing. It has been there for a month now. It disappeared for last 10 days but is reoccurred since last 2 days. Its frequency is 2 -3 times in a day. Now even when the pain attack is over a slight burning sensation persists.

    • Jan Modric says:

      I don’t know but it sounds it could be a strained/ruptured muscle or even a broken shoulder blade or rib. I suggest you to visit a doctor.

  11. Juliette Louise Regan says:

    I have excrutiating upper left back pain in what seems like cramps! Its starts there and then goes through to the chest! My neck and shoulder Doctor told me my neck muscles are far too tight and pushing on my neck but having a knock on affect in the top left muscle are around my shoulder blades. Please help!!

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