Intercostal Muscle Strain

Intercostal muscles are those found within the rib cage. The external, interior and innermost layers of muscles work together to fill the space between the ribs.

The outermost layer of the external intercostal muscles sits immediately beneath the skin and originates from the lower border of the rib above, runs obliquely, and inserts into the upper border of the rib below. During breathing, it stretches the chest wall.

Internal intercostals, which run from the costal groove near the inferior border of the rib above to the upper border of the rib below, assist in lung collapse during expiration.

The innermost intercostal muscles cross more than one intercostal region and aid the function of the internal and external intercostals.

Intercostal muscle strain varies according to the type and intensity of the injury. The strain of intercostal muscles causes rib/chest pain, upper back pain, and affects the breathing pattern.

The patient will present with a shallow, short breathing pattern due to pain. It is an injury that affects the muscles between two or more ribs.

There are five muscles that make up the thoracic cage; the intercostals (external, internal, and innermost), subcostals, and transverses thoracic. These muscles act to change the volume of the thoracic cavity during respiration.

There are some other muscles that do not comprise the thoracic wall but do attach to it. These include the pectoralis major, minor, serratus anterior, and scalene muscles.


The intercostal muscles lie in the intercostal spaces between ribs. They are organized into three layers.

External Intercostals

There are 11 pairs of external intercostal muscles. They run inferoanteriorly from the rib above to the rib below and are continuous with the external oblique of the abdomen.

  • Attachments: Originate at the lower border of the rib, inserting into the superior border of the rib below.
  • Actions: Elevates the ribs, increasing the thoracic volume.
  • Innervation: Intercostal nerves (T1-T11).

Internal Intercostals

These flat muscles lie deep to the external intercostals. Like the external intercostals, they run from the rib above to the one below, but in an opposite direction (anteroposteriorly). They are continuous with the internal oblique muscle of the abdominal wall.

  • Attachments: Originates from the lateral edge of the costal groove and inserts into the superior surface of the rib below.
  • Actions: The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.
  • Innervation: Intercostal nerves (T1-T11).

Innermost Intercostals

These muscles are the deepest of the intercostal muscles and are similar in structure to the internal intercostals.

They are separated from the internal intercostals by the intercostal neurovascular bundle and are found in the most lateral portion of the intercostal spaces.

  • Attachments: Originates from the medial edge of the costal groove and inserts into the superior surface of the rib below.
  • Actions: The interosseous part reduces the thoracic volume by depressing the ribcage, and the interchondral part elevates the ribs.
  • Innervation: Intercostal nerves (T1-T11)

Mechanism of Injury

Intercostal muscle strain doesn’t usually happen with daily life activities; it happens when the muscles are weakened by overexertion of muscles, direct trauma from a fall or car accident, or blow from contact sports such as hockey, or repetitive torso twisting.

  • A direct strike to the rib cage, such as from a fall, a car accident, or injuries from contact sports like football or hockey. As the ribs are suddenly pulled apart, the intercostal muscles will stretch or rupture.
  • Twisting the torso includes twisting while lifting, twisting from a dancing position/yoga posture, and twisting while participating in sports like tennis and golf.
  • Excessive torso twisting can develop when the ribs are manipulated beyond of their typical range during sports.
  • Reaching upwards: As we can observe when painting the ceiling, prolonged overhead activities or lifting over shoulder place undue tension on the muscles.
  • Rowing or hitting a tennis ball are examples of repetitive forceful action.

Risk Factor

  • Physical labor, such as activities that include repetitive twisting, prolonged overhead activities, or frequent weight lifting,
  • High-thrust sports, where there’s repeated use of the arm, shoulder, and upper back, put stress on intercostal muscles.
  • Contact sports occur when a direct, sudden force hits the upper body.

Clinical Presentation

Symptoms vary according to the degree of muscle strain, the intensity, and the type of injury.

  • A direct hit or quick contact to the chest, or a fast increase in physical activity, might cause acute pain in the upper back or rib cage.
  • Muscle tension and stiffness are caused by muscles tensing up in response to injury, resulting in upper back pain and stiffness with movement.
  • If the intercostal muscles are still under strain from repetitive, progressive stress, pain will gradually intensify over days or weeks. This is a typical type after sports like baseball.
  • Breathing difficulties: When you have an intercostal muscle strain, your breathing pattern will be altered by the discomfort, and you will breathe shallowly to escape the pain. This could result in a reduction in blood oxygenation.
  • Tenderness in the muscles and ribcage surrounding the affected area.
  • Inflammation, such as that caused by a strained muscle, can cause swelling and heightened sensitivity in the affected area.
  • In certain rare circumstances, intercostal muscular edoema causes a blood clot surrounding the muscle, resulting in a hematoma.
  • Intercostal muscle tension causes pain when you cough, sneeze, or breathe deeply.

Diagnostic Procedures

Diagnostic imaging X-rays and MRIs are not needed for the diagnosis of an intercostal strain, but they’re used to rule out the possibility of rib fracture or internal organ injury.

Diagnosis is based on patient history and physical examination:

Patient History: Ask the patient about current symptoms, pain, when and how it started, and if there is a history of recent trauma and the patient’s physical activities,

Physical examination, palpation to define the area of tenderness, swelling. Instructions to do active movements of the torso and trunk to know to what extent it affects the function and movement.

Differential Diagnoses

Intercostal muscle strain is often confused with upper back pain because it is very immobile and damage is uncommon.

Upper back discomfort is caused by long-term bad posture, and the pain is described as a strong, burning ache that can migrate to the neck and shoulder, as well as being intermittent.

Unlike discomfort from a lung illness, which is difficult to pinpoint, intercostal strain is a result of trauma-induced overexertion activities and its area of pain may be detected by the patient.


Healing depends on the severity of the injury. In most cases, the time ranges from a few days to 8 weeks in the majority of cases, and in some cases it lasts longer, causing upper back pain.

The first piece of advice for the patient is to rest for a few days and apply ice back on the first two days of pain to eliminate the inflammation.

Holding a pillow to stabilize the injured, painful area during deep breathing and coughing.

Medical Management

  • Pain relief medication: such as acetaminophen to interfere with pain signals sent to the brain and minimize overall pain levels.
  • Muscle relaxant medications: in acute severe pain for a short term effect to reduce muscle tension and spasm.
  • Anti-inflammatory medications.

Physical Therapy Intervention:

Gate Pose position Stretch left side intercostals

Once the inflammation has been decreased, physical therapy will begin, focusing on pain management methods, stretching under supervision, endurance strengthening activities, posture improvement, and breathing exercises.

Breathing exercise, deep breathing exercise The patient is encouraged to use diaphragmatic breathing while supporting the area of pain with a pillow.

Stretching, tight muscles can produce muscle imbalance and faulty mechanism, but if the strain is caused by overstretching of the muscle, the greater stretch may trigger discomfort and result in muscle weakening, which should be treated by a strengthening program.

Strengthing exercise if there’s muscle imbalance, thoracic extension exercises with breath-holding for a few seconds, and breath out slowly and backward weight lifting exercise has shown to improve thoracic kyphosis and decrease intercostal muscle pain

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