The long thoracic nerve is a somatic motor nerve of the thoracic wall.
It supplies innervation to the serratus anterior muscle.
Course
The long thoracic nerve originates from the brachial plexus, recieving fibres directly from the anterior rami of spinal nerves C5-7.
It descends posteriorly to the brachial plexus and anteriorly to the posterior scalene muscle.
The nerve continues distally deep to the clavicle and superficial to the first and second ribs before continuing along the anterolateral thoracic wall. It divides into its terminal branches at the surface of the serratus anterior muscle.
Fig 1 – Course of the long thoracic nerve.
Motor Functions
The long thoracic nerve supplies motor innervation to the serratus anterior muscle. This muscle rotates the scapula, allowing the arm to be raised over 90 degrees. It also holds the scapula against the ribcage.
Damage to the long thoracic nerve can result in weakness of the serratus anterior, producing a characteristic “winged scapula” appearance.
