The nerve to subclavius is a small branch of the upper trunk of the brachial plexus. It supplies the subclavius, a short muscle tucked underneath the collarbone.

Location

Usually carries fibres from the C5 and C6 spinal nerve roots
Branches from the upper trunk of the brachial plexus
Travels downward and forward toward the underside of the clavicle
Enters the subclavius muscle on its deep surface

Function

Provides the motor signal to the subclavius muscle
Helps the muscle steady and slightly lower the clavicle
Contributes to fine control of the shoulder girdle rather than producing a large visible movement

Some people have an accessory branch from this nerve that joins the phrenic nerve. Anatomical variation is common and does not automatically cause symptoms.

Clinical Relevance

An isolated injury to this nerve is uncommon and usually difficult to identify from symptoms alone. It is more often discussed as part of the upper brachial plexus anatomy or during surgery near the clavicle.

Pain beneath the collarbone is not enough to identify this nerve as the source. Joints, muscles, vessels and other nerves occupy the same region.

Brachial plexus — the nerve network from which it branches
Clavicle — sits directly above the subclavius muscle
Sternoclavicular joint — one of the joints influenced by shoulder-girdle control

References

StatPearls. "Anatomy, Thorax, Phrenic Nerves." https://www.ncbi.nlm.nih.gov/books/NBK513325/
Standring S, ed. Gray's Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. Elsevier; 2020.

Nerve to Subclavius