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Portrait of Rhomboid muscles

Anatomy · Muscles

Rhomboid muscles

Rhomboid major and rhomboid minor

Upper back · deep to the trapezius, retract the shoulder blade

A pair of flat, diamond-shaped muscles lying deep to the trapezius between the spine and the inner edge of the shoulder blade. Rhomboid minor is the smaller, higher strip and rhomboid major the larger, lower one. They pull the scapula towards the spine, the movement of squeezing the shoulder blades together, and hold it against the chest wall.

How to spot them

  • ▸Two parallelogram-shaped sheets, minor above and major below, running down and out from the spine to the medial border of the scapula
  • ▸Deep to the trapezius and superficial to the erector spinae; fibres slope like an inverted V
  • ▸Origins from the spinous processes of C7 to T1 (minor) and T2 to T5 (major)
  • ▸Supplied by the dorsal scapular nerve, a branch of the C5 root of the brachial plexus

What to know

A pair of diamond-shaped muscles between the spine and the inner edge of the shoulder blade, lying under the trapezius

Rhomboid muscles — named for their rhomboid, or diamond, shape.

The action of squeezing the shoulder blades together, as in a rowing pull, relies on them

Rhomboid muscles — retraction of the scapula.

They arise from spinous processes of the seventh cervical to the fifth thoracic vertebrae and attach along the medial border of the scapula

Rhomboid minor arises at C7 to T1 and rhomboid major at T2 to T5.

Supplied by a nerve arising from the C5 root that pierces the middle scalene muscle and runs down beside the medial border of the scapula

Rhomboid muscles — the dorsal scapular nerve.

When they are weak the inner edge of the shoulder blade lifts from the back, a milder winging than that caused by the serratus

Rhomboid muscles — winging of the scapula on the medial side when the dorsal scapular nerve is injured.

The smaller upper part joins the medial border at the level of the spine of the scapula, and the larger lower part runs below the spine to the lower angle

Rhomboid muscles — minor above the spine of the scapula, major below.

Key ideas

  • With the serratus anterior, the rhomboids hold the scapula against the chest wall like a sling: one pulls the blade towards the spine, the other draws it round the ribcage.
  • Because they also rotate the scapula so that the socket points downwards, they act with the levator scapulae when the raised arm is lowered against resistance.

Quick-fire facts

  • •Rhomboid minor: origin from the nuchal ligament and the spinous processes of C7 and T1; insertion on the medial border of the scapula at the level of the spine
  • •Rhomboid major: origin from the spinous processes of T2 to T5; insertion on the medial border of the scapula between the spine and the inferior angle
  • •Action: retract the scapula and rotate it to lower the glenoid cavity; they also help to hold the scapula against the thoracic wall
  • •Nerve supply: the dorsal scapular nerve (C4 and C5, chiefly C5)
  • •Blood supply: the dorsal scapular artery, the deep branch of the transverse cervical
  • •They lie deep to the trapezius and superficial to the serratus posterior superior and erector spinae
  • •The name derives from the Greek rhombos, a diamond or lozenge shape
  • •The two rhomboids are separated by a thin strip of areolar tissue and are often described as one muscle
  • •The dorsal scapular nerve also supplies the levator scapulae

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