Expansion
Medial winging from long thoracic nerve palsy, lateral winging from spinal accessory nerve palsy
Mnemonic
Two nerves, two directions of winging:
- Long thoracic nerve (C5, 6, 7) to serratus anterior: medial winging, worse on pushing against a wall. The commonest cause
- Accessory nerve (CN XI) to trapezius: lateral winging, worse on abduction, often after posterior triangle surgery or lymph node biopsy
- Dorsal scapular nerve to the rhomboids: mild lateral winging
“C5, 6, 7 raise your arm to heaven” for the long thoracic roots, and the arm cannot be raised above the horizontal once it is injured.
Expansion
- Medial winging - long thoracic nerve palsy weakens serratus anterior; the scapula moves medially and wings out, worse on pushing against a wall
- Lateral winging - spinal accessory nerve palsy weakens trapezius; the scapula drifts laterally, worse on arm abduction
Serratus anterior is the common culprit, so long thoracic nerve injury is the classic cause of a winged scapula.