The subclavius is a small muscle sandwiched between the clavicle and first rib. Its primary function is clavicular stabilisation and its most clinically important role is providing a cushion between clavicular fracture fragments and the underlying neurovascular bundle.
| Origin | Junction of the first rib and its costal cartilage |
|---|---|
| Insertion | Inferior surface of the middle third of the clavicle |
| Nerve Supply | Nerve to subclavius (C5, C6) — branch of the upper trunk of the brachial plexus |
| Blood Supply | Clavicular branch of thoracoacromial artery |
| Actions | Depresses and stabilises the clavicle during shoulder movements; Protects the brachial plexus and subclavian vessels from clavicular fracture fragments |
|---|
The nerve to subclavius (C5, C6) is the reference for upper trunk brachial plexus injuries — its integrity helps localise the injury level. Subclavius transfer has been described to restore elbow flexion in brachial plexus palsy. In claviculectomy, the subclavius must be included in the dissection.
Not directly palpable below the clavicle.
Electromyography of the subclavius localises brachial plexus injuries to the upper trunk level (C5, C6) when the nerve to subclavius is abnormal.
