Rhomboids Muscle Anatomy

Location & Overview

The rhomboid muscle group consists of rhomboid minor and rhomboid major. These are paired upper-back muscles that connect the vertebral column to the medial border of the scapula. They lie deep to trapezius, so they are usually hidden unless the superficial trapezius layer is removed.^[1,2]

Rhomboid minor is the smaller and more superior of the two muscles. It lies immediately inferior to levator scapulae and superior to rhomboid major. Rhomboid major is larger, broader, and inferior to rhomboid minor.^[1,2]

The rhomboids sit in the medial scapular region. They pass obliquely from the lower cervical and upper thoracic midline region toward the medial border of the scapula. This position allows them to pull the scapula toward the vertebral column and help control scapular position during upper-limb movement.^[1,2]

Rhomboid major and rhomboid minor are usually described as separate muscles, but variation can occur. They may fuse into a single muscle in some individuals, and accessory slips have also been described. These variants do not change the standard two-muscle teaching pattern.^[1,3]

Origin & Insertion

The rhomboids originate from the vertebral column and lower nuchal region, then insert on the medial border of the scapula. A spinous process is the posterior bony projection of a vertebra, and the nuchal ligament is the midline ligament in the posterior neck.^[1,2]

Rhomboid Minor Origin & Insertion

Rhomboid minor originates from the spinous processes of C7 and T1 and the nuchal ligament. It inserts on the medial border of the scapula superior to rhomboid major, near the medial end of the scapular spine.^[1,2]

Rhomboid Major Origin & Insertion

Rhomboid major originates from the spinous processes of T2-T5. It inserts on the medial border of the scapula below rhomboid minor, extending toward the inferior angle of the scapula. This longer scapular attachment matches its larger size compared with rhomboid minor.^[1,2]

Some detailed anatomical descriptions include supraspinous ligament attachments in the origin of rhomboid major and describe the scapular insertion as partly tendinous or membranous. Overall, rhomboid minor runs from C7-T1/nuchal ligament to the superior medial scapula, while rhomboid major runs from T2-T5 to the medial scapular border below it.^[1,2]

Action & Function

Both rhomboid major and rhomboid minor retract, or adduct, the scapula. Scapular retraction draws the shoulder blade medially toward the vertebral column, as when the shoulder blades are pulled together.^[1,2]

The rhomboids also elevate the scapula. Scapular elevation draws the shoulder blade upward. This action is shared with other scapular muscles, especially levator scapulae and the upper fibers of trapezius.^[1,2]

The rhomboids also assist downward rotation of the scapula. In this movement, the glenoid cavity, which is the lateral socket of the scapula for the humeral head, turns inferiorly. This is a scapular movement rather than a movement at the glenohumeral joint itself.^[2]

Beyond these named actions, the rhomboids help stabilize the scapula against the thoracic wall during upper-limb movement. This stabilizing role works with other scapular muscles, including trapezius and serratus anterior, to help hold the scapula in a useful position when force passes through the shoulder girdle.^[1,2]

Innervation

Rhomboid major and rhomboid minor are both innervated by the dorsal scapular nerve.^[1,2] The dorsal scapular nerve is usually described as arising from the C5 ventral ramus, although anatomical variation and some muscle tables describe C4-C5 contributions.^[1,2] Therefore, rhomboid innervation is most clearly listed by the named nerve: the dorsal scapular nerve, usually C5.

The dorsal scapular nerve runs near the anterior border of the rhomboid muscles and travels with the dorsal scapular artery near the medial border of the scapula. This neurovascular relationship is useful for understanding the deep medial scapular region.^[1]

Blood Supply

Rhomboid major and rhomboid minor are supplied by the dorsal scapular artery.^[1,4] The dorsal scapular artery usually arises from the second or third part of the subclavian artery, although variation is possible. It can arise from the thyrocervical trunk, and a deep branch of the transverse cervical artery can also contribute to rhomboid blood supply in some individuals.^[1,4]

Lai and Ho (2023) examined 79 sides from 41 Taiwanese cadavers and reported several dorsal scapular artery origin patterns, including origins from the transverse cervical artery, subclavian artery, and axillary artery. These findings describe that sample and should not be treated as universal prevalence values.^[5]