Musculi intercostales interni
The internal intercostals lie deep to the external intercostals. Their fibers run craniodorsally. They originate from the cranial border of each rib (internal surface) and insert on the caudal border of the adjacent cranial rib. Their main action is to depress the ribs during forced or active expiration. They are innervated by the intercostal nerves. They become more important during exercise and in respiratory disease when active expiration is needed.
Origin: Cranial border of each rib (internal surface)
Insertion: Caudal border of the adjacent cranial rib
Action: Depress the ribs during active expiration
Innervation: Intercostal nerves
Isolated injury is rare. The muscles can be affected by rib fractures or severe respiratory effort. They are part of the overall thoracic wall mechanics.
## Overview COPD involvement refers to the participation of chronic obstructive pulmonary disease (now termed severe equine asthma) in a horse’s overall clinical picture. Airway inflammation and obst
Increased respiratory effort or signs of breathing difficulty need veterinary evaluation. Rib trauma after a fall or kick can involve these muscles and the underlying structures.
## Overview COPD involvement refers to the participation of chronic obstructive pulmonary disease (now termed severe equine asthma) in a horse’s overall clinical picture. Airway inflammation and obstruction can limit performance, increase respiratory effort, and interact with other conditions such as cardiac disease or general fitness. ## Causes Environmental dust and mold exposure triggering lower-airway inflammation. ## Diagnosis History, clinical examination, endoscopy, and bronchoalveolar lavage. ## Treatment Environmental management plus corticosteroids and bronchodilators as needed. ## Recovery and Prognosis Manageable with consistent air-quality control. ## Prevention Low-dust husbandry. Signs include: cough; increased respiratory effort; exercise intolerance; nasal discharge; worsened by dusty environments
Isolated injury is rare. The muscles can be affected by rib fractures or severe respiratory effort. They are part of the overall thoracic wall mechanics.
Increased respiratory effort or signs of breathing difficulty need veterinary evaluation. Rib trauma after a fall or kick can involve these muscles and the underlying structures.
See the Internal Intercostals on our interactive 3D horse model. Open 3D Model