Rhomboid Major: Origin, Insertion, Nerve, Action & Scapular Stability

The Rhomboid Major is a geometric muscle of the upper back that connects the scapula to the spinal column. As its name implies, it is shaped like a rhombus (parallelogram). Working closely with the Rhomboid Minor, it is essential for scapular retraction ("squaring the shoulders") and overall posture.

[Image of Rhomboid Major muscle anatomy]

Quick Anatomy Snapshot

Origin (Proximal)	Spinous processes of T2 to T5 vertebrae.
Insertion (Distal)	Medial border of the Scapula (between the spine of the scapula and the inferior angle).
Nerve Supply	Dorsal Scapular Nerve (C5).
Blood Supply	Dorsal Scapular Artery.
Primary Actions	Retraction: Adducts the scapula (pulls shoulder blades together). Downward Rotation: Rotates the glenoid cavity downwards. Elevation: Weakly assists in lifting the scapula.

Deep Dive: The Posture Muscle

The Rhomboids lie deep to the Trapezius muscle, making them part of the extrinsic back muscles.

1. Major vs. Minor

The two Rhomboids are often fused, but anatomically distinct:
• Rhomboid Minor: Superior, attaches at the level of the scapular spine (C7-T1).
• Rhomboid Major: Inferior, attaches below the spine to the inferior angle (T2-T5).

2. The Antagonist Relationship

The Rhomboids are the direct antagonists to the Serratus Anterior.
• Rhomboids: Pull scapula In (Retraction).
• Serratus Anterior: Pulls scapula Out (Protraction).
A balance between these two is required to keep the scapula flush against the rib cage. Imbalance leads to "Winging of the Scapula."

Physio Corner: Clinical Relevance

💪 Functional Fact: In "Upper Crossed Syndrome" (rounded shoulders), the Rhomboids become lengthened and weak ("Locked Long"), while the Pectoralis muscles become tight. Strengthening the Rhomboids via rows and retraction exercises is key to fixing posture.

Palpation

To feel the Rhomboids, you must relax the superficial Trapezius.
Technique: Have the patient place the back of their hand on their lower back (internal rotation). Ask them to push their hand away from their back (lift off). Palpate along the medial border of the scapula. The muscle mass popping up deep to the Trapezius is the Rhomboid.

⚠️ Clinical Pathology: Dorsal Scapular Nerve Entrapment
Since the nerve supplying the Rhomboids (C5) often pierces the Middle Scalene muscle in the neck, tightness in the scalenes can entrap the nerve. This causes burning pain between the shoulder blades along the medial scapular border, often mistaken for a simple muscle strain.

Manual Muscle Testing (MMT)

We test Scapular Retraction and Downward Rotation.

Testing Tip: The patient puts their hand behind their back ("Chicken Wing" position). This position internally rotates the humerus and downwardly rotates the scapula, optimizing the Rhomboid line of pull.

Step-by-Step Procedure (Oxford Scale)

Grade	Patient Action & Resistance
Grade 3, 4, 5 (Against Gravity)	Position: Prone (face down). Arm internally rotated, back of hand resting on the lumbar spine. Action: Patient lifts the hand off the back (adducting the scapula). Resistance: Applied against the medial border of the scapula, pushing out (into abduction). Grade 3: Lifts hand clear of back. Grade 4/5: Holds against resistance.
Grade 2 (Gravity Eliminated)	Position: Sitting. Arm at side. Action: Patient attempts to squeeze shoulder blades together. Result: Full range of retraction.
Grade 0, 1 (Palpation)	Action: Palpate medial to the vertebral border of the scapula. Cue: "Try to pull your shoulder blade toward your spine." Grade 1: Deep contraction felt. Grade 0: No activity.

Frequently Asked Questions

Is it deep or superficial?

It is an intermediate layer muscle. It lies deep to the Trapezius but superficial to the Erector Spinae muscles.

Does it rotate the scapula upward or downward?

Downward Rotation. Because the fibers run obliquely downward from the spine to the scapula, contracting them pulls the glenoid cavity down. This opposes the Upper Trapezius and Serratus Anterior (Upward Rotators).

Why does it hurt "between the shoulder blades"?

This area is a common site for "trigger points" due to poor posture (slouching stretches the muscle constantly). It can also be referred pain from the neck (C5-C7 discs) or the stomach.

Test Your Knowledge: Rhomboid Major Quiz

1. Which nerve supplies the Rhomboid Major?

2. Where does the Rhomboid Major insert?

3. What is the primary action of the Rhomboids?

4. The Rhomboid Major lies deep to which muscle?

5. Where does the Rhomboid Major originate?

6. Weakness in the Rhomboids contributes to:

7. Which muscle is the antagonist to the Rhomboids?

8. The Rhomboid Major assists in which type of rotation?

9. Which artery supplies the Rhomboid Major?

10. To stretch the Rhomboids, you should:

References

• Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2018). Clinically Oriented Anatomy. 8th ed. Philadelphia: Wolters Kluwer.
• Standring, S. (2016). Gray's Anatomy: The Anatomical Basis of Clinical Practice. 41st ed. Elsevier.
• Kendall, F. P. (2005). Muscles: Testing and Function, with Posture and Pain. 5th ed. Lippincott Williams & Wilkins.