Musculus serratus dorsalis caudalis
Thin expiratory muscle drawing caudal ribs inward. Works antagonistically to its cranial counterpart during active expiration.
Origin: Thoracolumbar fascia from spinous processes of T15-L2
Insertion: Caudal border of last 4-5 ribs
Action: Retracts the caudal ribs during expiration
Innervation: Intercostal nerves
RAO/heaves increases expiratory effort, overworking this muscle and contributing to characteristic labored breathing.
RAO/heaves increases expiratory effort, overworking this muscle and contributing to characteristic labored breathing. Signs include: Pronounced abdominal effort during expiration; heave line; chronic cough; nasal discharge; poor body condition despite adequate feed.
See the Caudal Dorsal Serratus on our interactive 3D horse model. Open 3D Model