INTERCOSTALS

• Origin

 
External Intercostals: Inferior border of the rib above.
Internal Intercostals: Superior border of the rib below.
Innermost Intercostals: Similar to internal intercostals, but deeper and less distinct.

• Insertion

 
External Intercostals: Superior border of the rib below.
Internal Intercostals: Inferior border of the rib above.
Innermost Intercostals: Inner surface of the rib above.

• Agonist(s)

- Diaphragm (in respiration),

- Scalenes (in inspiration),

- Serratus posterior superior (in elevating ribs during inspiration).

• Antagonist(s)

- Abdominal muscles (e.g., rectus abdominis, internal/external obliques during forced expiration),

- Serratus posterior inferior (assists with forced expiration).

• Function

 
External Intercostals: Elevate ribs during inspiration to expand the thoracic cavity.

Internal and Innermost Intercostals: Depress ribs during forced expiration
Assist in stabilizing the intercostal spaces during respiration and movement.

TRIGGER POINT(S)

• Location

 
Trigger points can be found between the ribs, along the intercostal spaces.

Most commonly found in the mid-axillary line or near the costosternal junction.
 

Can affect any intercostal level, particularly T3–T7.

• Pain Referral Pattern

 
Pain may mimic visceral (organ) pain and can radiate around the ribcage in a horizontal band-like pattern.

May refer anteriorly to the chest or posteriorly to the thoracic spine and scapular region.

Can sometimes be mistaken for cardiac or gallbladder pain depending on the rib level involved.

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Potential Causes

 
• Deep or rapid breathing, especially during anxiety or respiratory distress.

• Persistent coughing or respiratory infections.

• Direct trauma or impact to the ribcage.

• Twisting or bending of the torso under load (e.g., during sports or lifting).

• Poor posture or prolonged forward-flexed positions.

• Rib subluxation or dysfunction.

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Prevention Tips

 
• Maintain good posture, especially when sitting or standing for long periods.

• Warm up adequately before physical activities involving the torso.

• Avoid repetitive or forceful twisting motions of the trunk.

• Strengthen and stretch thoracic and abdominal musculature to support rib motion.

• Practice deep, diaphragmatic breathing to avoid overuse of accessory respiratory muscles.