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Rhomboid minor muscle

The rhomboid minor muscle is a small, flat skeletal muscle located in the upper back between the spine and the medial border of the scapula. It is part of the rhomboid muscle group, situated superior to the larger rhomboid major. The rhomboid minor plays a key role in stabilizing, retracting, and rotating the scapula, contributing to proper shoulder posture and movement. Understanding its detailed anatomy, nerve and blood supply, and imaging characteristics is essential for diagnosing musculoskeletal and neurological conditions involving the upper back.

Synonyms

  • Rhomboideus minor

  • Musculus rhomboideus minor

Function

  • Retracts (adducts) the scapula toward the vertebral column

  • Elevates the medial border of the scapula

  • Rotates the scapula to depress the glenoid cavity

  • Stabilizes the scapula during upper limb movements

Origin

  • Lower part of the nuchal ligament

  • Spinous processes of the C7 and T1 vertebrae

Insertion

  • Medial border of the scapula at the level of the spine of the scapula (superior to the insertion of the rhomboid major)

Nerve Supply

  • Dorsal scapular nerve (C4, C5 nerve roots; predominantly C5)

Artery Supply

  • Dorsal scapular artery (also known as deep branch of the transverse cervical artery)

  • Small branches from the upper posterior intercostal arteries

Vein Supply

  • Dorsal scapular vein

  • Tributaries draining into the subclavian vein

MRI Appearance

  • T1-weighted images: The rhomboid minor appears as a well-defined, intermediate signal intensity structure between the hyperintense (fatty) subcutaneous tissues and the hypointense cortical bone of the scapula and vertebrae.

  • T2-weighted images: Normal muscle demonstrates relatively low signal intensity, but increased signal may indicate edema or pathology.

  • STIR (Short Tau Inversion Recovery): The rhomboid minor muscle appears as low to intermediate signal; areas of muscle edema, inflammation, or acute injury will appear hyperintense (bright) on STIR images.

CT Appearance

  • The rhomboid minor muscle is seen as a soft tissue structure of uniform density, posterior to the thoracic cage and adjacent to the scapula, distinguishable from surrounding fat and bone. CT is less sensitive than MRI for soft tissue differentiation but can identify muscle atrophy, masses, or traumatic injuries.

MRI images

Rhomboid minor muscle axial mri image

MRI image

Rhomboid minor muscle anatomy MRI axial image -img-00000-00000_00001

CT images

Rhomboid minor muscle anatomy CT axial image -img-00000-00000

CT images

Rhomboid minor muscle anatomy MRI axial image -img-00000-00000