Musculi intercostales externi
The external intercostal muscles lie between the ribs with fibers running caudoventrally. They originate from the caudal border of each rib and insert on the cranial border of the adjacent caudal rib. Their action is to elevate the ribs during inspiration, expanding the thorax. They are innervated by the intercostal nerves and are active with every breath. They work with the diaphragm and other muscles to increase thoracic volume for air intake.
Origin: Caudal border of each rib
Insertion: Cranial border of the adjacent caudal rib
Action: Elevate the ribs during inspiration, expanding the thorax
Innervation: Intercostal nerves
Rarely a primary source of pathology. They can be involved in rib fractures or thoracic trauma. Intercostal nerve blocks are occasionally used for pain management.
## Overview Kicks or falls can tear intercostal muscles or fracture ribs, causing severe pain with every breath. Horses breathe shallowly, are reluctant to move, and may show pain between the ribs. S
Labored breathing or pain with chest movement after trauma should be evaluated. Most intercostal issues are secondary to rib or thoracic injury.
## Overview Kicks or falls can tear intercostal muscles or fracture ribs, causing severe pain with every breath. Horses breathe shallowly, are reluctant to move, and may show pain between the ribs. Subcutaneous emphysema or pleuritis can develop. The pain can mimic colic. ## Causes Blunt trauma. ## Diagnosis Palpation, ultrasound of the chest wall, and radiographs. Thoracocentesis if pleural fluid is suspected. ## Treatment Pain control, rest, and management of complications (pneumothorax, hemothorax, or pleuritis). Most simple fractures heal with time. ## Recovery and Prognosis Good for uncomplicated cases. Complications worsen the outlook. ## Prevention Safe group housing and fencing. Signs include: shallow breathing; reluctance to move; pain between ribs; possible subcutaneous emphysema; may mimic colic; fever if pleuritis develops
Rarely a primary source of pathology. They can be involved in rib fractures or thoracic trauma. Intercostal nerve blocks are occasionally used for pain management.
Labored breathing or pain with chest movement after trauma should be evaluated. Most intercostal issues are secondary to rib or thoracic injury.
See the External Intercostals on our interactive 3D horse model. Open 3D Model