Musculus serratus dorsalis cranialis
The cranial dorsal serratus (serratus dorsalis cranialis) is a thin, fan-shaped muscle that originates from the thoracolumbar fascia (spinous processes approximately T1–T8) and inserts on the lateral surfaces of ribs 5–11. Contraction draws those ribs cranially and laterally, increasing thoracic volume and assisting inspiration. It becomes more active during exercise when respiratory demand rises. It is innervated by the intercostal nerves and works opposite the caudal dorsal serratus. Isolated injury is rare; it is more often affected secondarily by rib trauma or severe thoracic disease.
Origin: Thoracolumbar fascia from spinous processes of T1-T8
Insertion: Lateral surface of ribs 5-11
Action: Draws ribs cranially and laterally, assisting inspiration
Innervation: Intercostal nerves
Not a primary clinical target. Rib fractures or pleuropneumonia can involve the overlying or adjacent musculature. Reduced chest-wall movement may be noted on physical examination.
## Overview Horses with severe equine asthma (heaves/RAO) have an increased work of breathing. Increased abdominal effort can cause hypertrophy of the external abdominal oblique muscles, producing th
Any horse showing labored breathing after trauma to the chest should be seen by a veterinarian. Most minor muscle strains resolve with rest.
## Overview Horses with severe equine asthma (heaves/RAO) have an increased work of breathing. Increased abdominal effort can cause hypertrophy of the external abdominal oblique muscles, producing the heave line. Horses show labored breathing at rest, prolonged recovery after exercise, nostril flaring, and a double expiratory effort. ## Causes Chronic airway obstruction from allergic inflammation. ## Diagnosis Clinical signs of heaves and confirmation of lower-airway inflammation. ## Treatment Environmental control plus medications to reduce airway resistance, thereby decreasing the work of breathing. ## Recovery and Prognosis Fatigue improves when airway obstruction is controlled. ## Prevention Strict dust management in susceptible horses. Signs include: heave line; labored breathing at rest; prolonged recovery after exercise; nostril flaring; double expiratory effort
Not a primary clinical target. Rib fractures or pleuropneumonia can involve the overlying or adjacent musculature. Reduced chest-wall movement may be noted on physical examination.
Any horse showing labored breathing after trauma to the chest should be seen by a veterinarian. Most minor muscle strains resolve with rest.
See the Cranial Dorsal Serratus on our interactive 3D horse model. Open 3D Model