Tags: Anatomical Structure, Nerve.
The long thoracic nerve (external respiratory nerve of Bell; posterior thoracic nerve) supplies the serratus anterior. This nerve characteristically arises by three roots from the fifth sixth and seventh cervical nerves (C5-C7) but the root from C7 may be absent. The roots from C5 and C6 pierce the scalenus medius while the C7 root passes in front of the muscle. The nerve descends behind the brachial plexus and the axillary vessels resting on the outer surface of the serratus anterior.
