The proper names for the muscles we call the rhomboids are Rhomboideus Major and Minor or the Rhomboidei. Although two different muscles, they are very difficult to distinguish from one another and perform the same actions together. They run obliquely downward from the spine to the inner edge of the scapula, on each side of the middle back and connect the vertebra in that area to the medial border of the scapula. They are largely covered by the more superficial trapezius muscle.
The rhomboids get their name from their shape, the word rhomboideus referring to a diamond or kite shaped object. In geometry, a rhomboid is a parallelogram having adjacent sides of unequal length and oblique angles. The rhomboids are often said to be rhombus shaped but this is not entirely accurate as a rhombus and rhomboid are two different shapes.
The rhomboid minor begins at the last vertebra of the neck (cervical) and ends at the first thoracic vertebra. The rhomboid major begins where the minor leaves off, at the second thoracic vertebra and continues to the fifth thoracic vertebra. The rhomboid major is bounded by the latissimus dorsi inferiorly and the minor is bounded by the levator scapula, superiorly. They share their attachment to the medial scapular border with the trapezius and levator scapulae muscles.
The rhomboids are used anytime you forcefully lower your arms or pull down or back with them, as when performing pullups or drawing back a bowstring. They are also important as brakers of scapular protraction during throwing movements, and are also active when walking, stabilizing the scapula during the arm swing.
Rhomboids Origin, Insertion, and Actions
Origin: The rhomboid minor originates on the spinous processes and nucal ligaments (ligamentum nuchae) of vertebrae C7 through T1. The rhomboid major originates on the spinous processes of vertebrae T2 to T5 (last neck vertebra and first five thoracic vertebrae.
Insertion: The rhomboid minor inserts onto the medial border of the scapula, at the level of the spine. The rhomboid major inserts onto the medial border of the scapula, inferior to the spine.
Actions: Similar to the middle fibers of the trapezius, the rhomboids major and minor retract (adduct) the scapula and cause slight elevation of the scapulothoracic. They also rotate the scapula downward to depress the glenoid cavity and help hold the scapula close to the thoracic wall. In this way, although they are agonists with the middle trapezius, they are antagonists for the upward scapular rotation of the upper and lower traps, similar to the levator scapula. These actions make the major role of the rhomboids is as a scapular stabilizer and they fix the scapula into adduction when the shoulder joint is adducted or the arm is extended forcefully. They keep the lower angle of the scapula close to the ribs, keeping it from protruding outward and causing scapular winging when pushing against something in front of you, as when performing the pushup or leaning against a wall, etc. 1Rockwood, Charles A. The Shoulder. Philadelphia, PA: Saunders/Elsevier, 2009. 55.,2Davies, Clair. The Trigger Point Therapy Workbook: Your Self-treatment Guide for Pain Relief. Oakland, CA: New Harbinger Publications, 2004.,3Simons, David G., Janet G. Travell, Lois S. Simons, and Janet G. Travell. Travell & Simons’ Myofascial Pain and Dysfunction: the Trigger Point Manual. Baltimore: Williams & Wilkins, 1999. 425-430.
Rhomboid Synergists and Antagonists
|Rhomboids Major and Minor||Serratus Anterior|
|Trapezius Middle Fibers||Pectoralis Minor|
|Downward Rotation||Upward Rotation|
|Rhomboids Major and Minor||Trapezius Upper Fibers|
|Levator Scapula||Trapezius Lower Fibers|
Sources [ + ]
|1.||↲||Rockwood, Charles A. The Shoulder. Philadelphia, PA: Saunders/Elsevier, 2009. 55.|
|2.||↲||Davies, Clair. The Trigger Point Therapy Workbook: Your Self-treatment Guide for Pain Relief. Oakland, CA: New Harbinger Publications, 2004.|
|3.||↲||Simons, David G., Janet G. Travell, Lois S. Simons, and Janet G. Travell. Travell & Simons’ Myofascial Pain and Dysfunction: the Trigger Point Manual. Baltimore: Williams & Wilkins, 1999. 425-430.|