Long Thoracic Nerve
The Long Thoracic nerve arises from spinal nerve roots C5, C6, and C7. It then courses laterally through the scalenus medius over the first rib and descends on the serratus anterior.
Injury to the long thoracic nerve results in paralysis of the serratus anterior muscle. If the upper limb encounteres anterior resistance, the medial border of the scapula protrudes posteriorly. This condition is known as winged scapula.