Muscle
Pectinate muscles
Ridged atrial muscle concentrated in the appendages
High-yield
Atrial pectinate muscles differ from ventricular trabeculae carneae. Their distribution helps distinguish the atria, especially the broad pectinate region on the right.
Overview
Pectinate bundles create ridges inside both atrial appendages and much of the anterior right atrium. On the right they extend from the crista terminalis; the main left atrial chamber is comparatively smooth.
Reference facts
- Origin
- Right-sided bundles extend from the crista terminalis; left-sided bundles arise in the appendage wall
- Insertion
- Merge into neighboring atrial myocardium within the appendages and right atrial wall
- Innervation
- Sympathetic and parasympathetic fibers through cardiac neural networks
- Action
- Participate in atrial contraction and ventricular filling
- Blood supply
- Atrial branches from the right and left coronary systems
Clinical correlation
The appendages contain thin wall between muscular ridges. This architecture matters during imaging and catheter procedures, and left appendage stasis in atrial fibrillation can favor thrombus formation.
Frequently asked questions
What do the pectinate muscles do?
Participate in atrial contraction and ventricular filling.
What nerve innervates the pectinate muscles?
The pectinate muscles are innervated by the sympathetic and parasympathetic fibers through cardiac neural networks.
Where do the pectinate muscles attach?
Origin: Right-sided bundles extend from the crista terminalis; left-sided bundles arise in the appendage wall. Insertion: Merge into neighboring atrial myocardium within the appendages and right atrial wall.
What is the blood supply of the pectinate muscles?
The pectinate muscles are supplied by the atrial branches from the right and left coronary systems.