Accessory surfs, plexus peeks, artery anchors
Mnemonic
Group by type:
Nerves: accessory nerve (XI) crossing superficially, the cervical plexus branches at Erb’s point, the brachial plexus roots and trunks emerging between the scalenes, and the phrenic nerve on scalenus anterior.
Vessels: the third part of the subclavian artery, the transverse cervical and suprascapular arteries, and the external jugular vein.
Muscles of the floor: splenius capitis, levator scapulae, and the scalenes.
Lymph nodes: the level V group, and the supraclavicular nodes.
“The accessory nerve is the one at risk”: it crosses the triangle superficially in the investing fascia at about the junction of the upper and middle thirds of sternocleidomastoid, and it is the commonest nerve injured during lymph node biopsy, causing trapezius weakness and lateral winging.
A supraclavicular node here on the left is Virchow’s node, signalling intra-abdominal malignancy.
Expansion
- Accessory nerve - runs superficially across the triangle
- Brachial plexus roots and trunks - emerge in the lower part
- Third part of the subclavian artery - crosses the base