External Intercostal Muscles: What They Do, Pain Signals & How to Assess Injury

External Intercostal Muscles What They Do, Pain Signals & How to Assess Injury

Your ribs stretch up and out every time you breathe in, then squeeze back down with each exhalation. The external intercostal muscles that are positioned between each rib take care of these movements. 

You use these muscles thousands of times a day without even noticing. They can also become painful at times, and that discomfort is often mistaken for heart-related pain because these muscles are connected to the heart and lungs. 

Speaking of which, this article is meant to clear all your doubts about the external intercostals. What they are for, how they become injured and how to know if the pain between your ribs is muscular or something serious.

Here’s what you’ll learn:

  • What are External intercostal muscles? 
  • Where are they and how do they differ from other chest muscles?
  • What does External Intercostals Pain feel like?
  • When symptoms point to a muscle strain vs. when you should go to the doctor?

What Are The External Intercostal Muscles?

Your rib cage, after all, is not a rigid box. It rises and it falls, sort of like you’re throttling a bike and your external intercostals are largely responsible for that ability. These extend from rib to rib and together they are like a stack of cards that can get taller, which allows your chest volume to increase when you breath in.

The fibers of these muscles angle downward and forward from one rib to another, which means they work at a mechanical advantage to hoist the rib cage up and out when you inhale.

External intercostal Muscles remain active at all times, and at rest, they roll with plain old quiet breathing. Their job becomes much harder when you breathe more intensely or deeply, during strenuous exercise or acute bronchitis.

The engagement of these muscles is continuous, making them particularly prone to overuse, strain and irritation.  The external intercostal muscles also work alongside the diaphragm and other breathing muscles. When one part of this system is under stress, other parts can offer compensations that might cause pain to be amplified or seem to spread across the chest wall.

The Anatomy and Mechanics of the External Intercostal Muscles

The Anatomy and Mechanics of the External Intercostal Muscles

The external intercostals serve one purpose only, which is to elevate the rib cage during inhalation. Their constituency does that job, and understanding it makes them significantly easier to read for the patterns they present when in pain.

These muscles are interconnected from the front and backwards of one rib cage to another (between each pair of ribs). They arise from the rib tubercles on the back and pass forwards to be lost in a delicate connective tissue anterior to the sternum. In this position, they act as levers at the ribs.

When the external intercostals contract they pull the lower rib upward toward and against the rib above it. When several ribs simultaneously rise and fall, the chest expands to accommodate the air filling the lungs.

This function is most apparent in:

  • Deep breathing.
  • Physical exertion.
  • Shortness of breath.
  • Coughing or sneezing.

Unlike many muscles (which can lay dormant when you’re not using them), the external intercostals hardly ever get a break. Even with easy breathing, they help the diaphragm stabilize and raise the rib cage.

Since they connect directly to the ribs, irritation or weight doesn’t remain subtle. The pain is typically sharp or catching and occurs at the site where your ribs are most mobile. Every breath reminds us that the muscle is there.

The intercostal muscles assist the external intercostals in their rib function job. If fatigue is present within the diaphragm or if breathing mechanics are disrupted from body position, disease, or anxiety, the external intercostals might step in and overfunction. This added weight further increases the risk for strain and inflammation.

How the External Intercostals Work During Breathing

Breathing may seem instinctive, but it’s a series of precisely timed steps between multiple muscle groups, and the external intercostals are no small players in this process. Each time you take a breath, they expand and lift the rib cage to make room for your lungs to fill with air.

While breathing quietly, the diaphragm takes on most of the work, but the external intercostals are right there in case we need a little assistance, working to subtly reposition the ribs enough to allow for better air flow. 

When you breathe deeply, such as while working out or exerting yourself, the external intercostals become more involved and contract with greater force to raise ribs up and expand chest.

Unlike the skeletal muscles in your limbs, which you can give a break by sitting still or lying down, these muscles never rest; they work every time you breathe. Pain or ache will be consistent and will be felt, moist often sharp or taut, on deep breath in.

External intercostals also coordinate with:

  • The internal intercostal muscles, primarily aiding in exhalation.
  • The diaphragm, main inspiratory muscle.
  • Accessory muscles such as the scalene, and sternocleidomastoid in deep inspirations.

When one of these muscles is fatigued or injured, the other attempts to pick up the slack, sometimes with even more discomfort and referred pain in surrounding regions like the chest wall or upper back.

Typical Injuries and Pain Patterns of the External Intercostals

Since these muscles are engaged with every breath, small strains can feel large.

Strains and Overuse Injuries

A strain happens when the muscle fibers are stretched or torn, but not completely severed. Common triggers include:

  • Repetitive or forceful coughing.
  • Sudden twisting movements.
  • Exercise that requires violent twisting of the torso or heavy breathing.

Trigger Points and Referred Pain

Sometimes small knots, or “trigger points,” form in the external intercostals. These points can:

  • Cause stabbing or throbbing pain in the area.
  • Transfer pain to other regions on or near the head.

How do you make the pain feel more diffuse and confusing?

Trigger point pain also may be aggravated by touch or pressure, which is a characteristic that separates it from cardiac or lung-related chest pain.

Costochondral vs Intercostal Pain

Pain in the external intercostals may be misinterpreted as costochondritis, inflammation of the cartilage that attaches a rib to the sternum. Both conditions result in concentrated chest pain:

  • The pain is usually felt between the ribs, and increases with movement or taking deep breaths.
  • Costochondritis pain is located closer to the breastbone and may worsen when pressing on the cartilage.
  • Both are commonly benign, but their location and reproducibility with movement can help distinguish them.

External Intercostal Pain vs Other Chest Pain Sources

Pain in the chest is troublesome because the external intercostals have nerve supply in common with the heart and lungs. The difference is in thinking about how the pain acts.

The pain of external intercostal is mechanical such as it changes with movements, pressure or position. It may sharpen when you take a deep breath, or cough, or twist your torso or lift something. 

Heart pain or the heart attack on the other hand, usually does not get better with movement or touch and may feel like pressure, heaviness or tightness that travels to your arm, neck or jaw.

Other causes of a chest symptom include:

  • Pain relating to the lungs: Usually sharp pain that hurts more when you breathe in, possibly with difficulty breathing, cough or fever.
  • Rib Injuries: Pain is generally localized, increases on direct impact or movement and there may be visible swelling/bruise.
  • Internal Intercostal Muscles: Found toward the inside of the external intercostals, they help you exhale; it can even feel like strain here but is often much more subtle during inhalation.

Self-Assessment Test For External Intercostal Pains

Self-Assessment Test For External Intercostal Pains

The majority of people get chest pain and worry it’s serious. The fact is, intercostal pain from the outside operates by certain conventions, and you can learn to look at them safely. This model provides you a road map for learning about your symptoms.

Step 1: Pinpoint the Pain

  • Can you pinpoint the pain to a certain spot between your ribs?
  • While applied pressure in the region, does mild pressure mimic the pain?

What it means: Localized and reproducible pain would point toward muscular or intercostal origins of the discomfort versus heart or lung etiologies.

Step 2: Observe Movement Response

  • Take a deep breath. Does the pain worsen?
  • Twist your torso slowly. Does the discomfort change?
  • Cough gently. Is the pain triggered?

What it means: Pain that gets worse with breathing or movement is a sign of involvement of the external intercostals. Pain of the heart typically does not behave in this manner.

Step 3: Assess Onset and Active Periods 

  • Was the pain precipitated by exertion, coughing, or a rapid change in position?
  • Did it come on slowly, with no apparent cause?

What it means: An acute onset with activity implies strain or overuse. Unprovoked pain needs to be quite closely observed.

Step 4: Look for Other Symptoms

  • Difficulty breathing independent of pain?
  • Nausea, sweating, lightheadedness or heaviness in your chest?

What it means: Patients with these symptoms may need to be urgently evaluated, even if pain appears muscular.

Step 5: Monitoring response to rest and posture

  • Is the pain relieved by changing position or resting?
  • Is the pain present even while at rest?

What it means: Pain that gets better with rest and variably, with change in position is typically muscular. Warning signs: Continuous or unaltered pain should be a red flag.

When to See a Healthcare Provider

While pain of the external intercostal muscle is frequently muscular, and therefore benign in nature, it can cause sufficient discomfort for which medical attention is warranted. Being able to tell the difference between ordinary muscle aches and bad news helps you get care when care is due, but without needless freakouts.

You should seek evaluation if:

  • This is your new episode of unexplained chest pain.
  • Pain is not affected by changes in position, movement or breathing; and cannot be relieved with pressure.
  • Pain is more like pressure, fullness, or squeezing than a sharp or pulling feeling.
  • The beginning of pain occurred suddenly at rest (particularly without effort).
  • You have other symptoms with the chest pain, such as shortness of breath, nausea, sweating, dizziness or unusual fatigue.
  • You have a history of heart disease, lung disease or chest injury in the past few weeks.

Early assessment helps eliminate undue anxiety, leads to accurate diagnosis and dictates appropriate treatment, especially if the sprain is in the moderate-to-severe category.

At places like Aether Health ER, rapid testing, such as EKGs and blood work, helps to differentiate between a heart-related event or something more muscular in nature. 

How To Treat and Recover Your External Intercostal Pain

How To Treat and Recover Your External Intercostal Pain

When the pain is diagnosed as external intercostal strain, treatment is directed toward pain reduction, healing and normal visceral breathing. As these muscles are used with every breath, looking after them is crucial to an effective recovery.

Rest and Activity Modification

Rest doesn’t mean complete immobility. That means you’ll need to steer clear of movements that trigger the muscle, like heavy lifting, twisting or coughing forcefully. Gentle respiration and ambulation help to keep the rib mobile without overworking the muscle injured.

Ice and Heat Therapy

Ice: Helpful in the first 24–48 hours to lower inflammation and for pain.

Heat: May be relaxing to tight muscles and may increase blood flow after the acute phase.

Pain Management

Non-steroidal anti-inflammatory drugs may be useful, but rest, correcting posture and breathing technique can offer relief without the use of medication. Don’t push through sharp pain, which can worsen the strain.

Stretching and Posture

Reconnecting to mobility Gentle stretching and posture exercises can restore movement and prevent stiffness, once the acute pain has improved. Focus on:

  • Mobility in the chest and ribcage.
  • Shoulder and upper back strengthening
  • Gradual increases in activity intensity
  • Steer clear of stretches that give you a sharp pain; these muscles are meant for slow, deliberate movement.

Physical Therapy

Physical therapy may be advised for chronic pain or moderate to severe strains. Targeted exercises:

  • Strengthen supporting muscles.
  • Correct posture imbalances.
  • Improve breathing mechanics.
  • Prevent recurrent intercostal strain.

Recovery Timeline

Mild sprain: Normally responds to rest and gentle treatment in 1–2 weeks.

Mild strain: 3–6 weeks, especially if the pain lingers when doing activity.

Serious strain: This can take 8–12 weeks or even longer to heal and occasionally requires medical intervention.

Take Away

External intercostal muscles may be tiny, but they play a big role in every breath that you take. Since they are working all of the time, even minimal stress can appear aggressive, sustained and frightening. Knowing what they do and how their pain symptoms act is the first step in being able to react accordingly.

Here’s what to remember:

  • Pain between the ribs that is made worse with deep breathing, twisting or pressure typically represents a muscular origin.
  • External causes of intercostal pain will tend to come with changes in posture, or induced by pressure – cardiac or lung pain normally does not.
  • Watching onset, triggers and response to rest can help discern muscle pain from serious conditions.
  • A mild strain may resolve after a couple of weeks, while moderate or severe strains require careful management, stretching at home and sometimes physical therapy.

Frequently Asked Questions (FAQs)

1.What are the external intercostal muscles?

They are the outermost muscles between your ribs that help expand the chest during breathing by lifting the rib cage.

2.Why do my external intercostal muscles hurt?

They commonly hurt due to muscle strain from coughing, twisting, heavy lifting, poor posture, or sudden movements that overstretch the rib muscles.

3.Where is Silver Lake ER located?

Silver Lake ER is located at 2752 Sunrise Blvd, Pearland, TX 77584 and it is a 24/7 emergency facility, providing rapid evaluation, testing, and treatment when urgent care is needed.

4.What is the main function of the intercostal muscle?

Their primary function is to support breathing by stabilizing the rib cage and assisting chest expansion during inhalation.

5.What is the difference between external intercostal muscles and membrane?

External intercostal muscles actively assist breathing, while the external intercostal membrane is a fibrous extension that provides structural support where muscle fibers end.

Last updated on January 16, 2026
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