Rhomboid minor muscle

At a glance

English

Rhomboid minor muscle

Latin (TA2)

Musculus rhomboideus minor

System

Muscle

Region

Back

Side

Paired, left and right

About the rhomboid minor muscle

Rhomboid minor is the smaller and higher of the two rhomboid muscles. It sits between levator scapulae above and rhomboid major below, under trapezius and over the deep spinal muscles. It is usually separated from rhomboid major by a narrow gap, though the two can be joined at their edges.

Its fibres come from the bottom of the nuchal ligament, the spines of C7 and T1 and the supraspinous ligament between them. They run down and outward as a narrow band and end on a short stretch of the scapula's medial border opposite the root of the scapular spine.

Working with rhomboid major, it draws the scapula towards the vertebral column and helps to keep it against the chest wall. With levator scapulae it lifts the scapula's medial border and turns the glenoid downward. During movements of the arm it acts as a stabiliser, holding the scapula steady while other muscles move the shoulder. Bracing the shoulders back, as when standing to attention, brings both rhomboids into play.

Its nerve is the dorsal scapular nerve, carrying mainly C5 fibres with small contributions from C4 or C6, and its blood comes from the dorsal scapular artery. Weakness of the rhomboids lets the scapula slide outward, and tender points in the muscle are a frequent cause of aching between the shoulder blades.

Attachments, action and supply

Origin

Lower nuchal ligament, spines of C7 and T1, and the supraspinous ligament between them.

Insertion

Medial border of scapula opposite the root of the scapular spine.

Action

Retracts the scapula, holds it to the chest wall and helps rotate the glenoid downward.

Nerve supply

Dorsal scapular nerve (mainly C5).

Blood supply

Dorsal scapular artery.