Rhomboideus minor is a small quadrilateral muscle, which lies between rhomboideus major inferiorly and levator scapulae superiorly in the posterior neck and chest wall, superficial to the long back muscles and deep to trapezius.

Proximal Attachment
It arises from the lower part of the ligamentum nuchae, the spinous processes of C7 and T1 and intervening supraspinous ligament.

Distal Attachment
The fibers pass obliquely infero-laterally to attach to the smooth triangular surface at the medial end of the scapular spine by anterior and posterior layers, which enclose the inferior border of levator scapulae.  The anterior layer is wide and strong, extending medial to and below levator scapulae, while the posterior layer attaches to the rim of the triangular surface behind and below levator scapulae.

Nerve Supply
The dorsal scapular nerve, derived from C4 and C5, supplies rhomboideus minor.  

Action
Together with rhomboideus major, levator scapulae and pectoralis minor it medial rotates the scapula; with rhomboideus major and trapezius it retracts the scapula.

For more information on the shoulder see 'The Interactive Shoulder'.