Rhomboid Major Muscle
Origin: The spinous processes of T2 to T5
Insertion: Vertebral border of the scapula, from inferior to the scapular spine to the inferior angle
Actions: Retraction of the scapula, downward rotation of the scapula
Innervation: Dorsal scapular nerve (C5)
Blood Supply: Dorsal scapular artery and dorsal branches of the posterior intercostal arteries
Primary Actions of the Rhomboid Major
1. Retraction of the scapula
Agonists:
- Trapezius (middle part)
- Rhomboid minor
Antagonists:
- Serratus anterior
- Pectoralis minor
Secondary Actions of the Rhomboid Major
2. Downward rotation of the scapula
Agonists:
- Levator scapulae
- Serratus anterior (upper fibers)
- Rhomboid minor
- Pectoralis minor
- Trapezius (middle fibers)
Antagonists:
- Trapezius (upper and lower part)
- Serratus anterior (lower fibers)
Middle part of trapezius is a stabilizer.
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Rhomboid Minor Muscle
Origin: Nuchal ligament and the spinous processes of C7 and T1
Insertion: The vertebral border of the scapula, adjacent to the scapular spine
Actions: Retraction of the scapula, downward rotation of the scapula
Innervation: Dorsal scapular nerve (C5)
Blood Supply: Dorsal scapular artery and dorsal branches of the posterior intercostal arteries
Primary Actions of the Rhomboid Minor
1. Retraction of the scapula
Agonists:
- Trapezius (middle part)
- Rhomboid major
Antagonists:
- Serratus anterior
- Pectoralis minor
2. Downward rotation of the scapula
Agonists:
- Levator scapulae
- Serratus anterior (upper fibers)
- Rhomboid major
- Pectoralis minor
- Trapezius (middle fibers)
Antagonists:
- Trapezius (upper and lower part)
- Serratus anterior (lower fibers)
Middle part of trapezius is a stabilizer.
Muscle Pain Information: The rhomboid muscles contribute to pain in the upper back around the inside edge of the scapula.