Medial pectoral nerve

Damage to the medial pectoral nerve can result in inability to elevate the shoulder.

Anatomy

Origin

The medial pectoral nerve usually arises from the medial cord of the brachial plexus; it can however occasionally arise directly from the anterior division of the inferior trunk of the brachial plexus. It is derived from the eighth cervical (C8) and first thoracic (T1) spinal nerve roots.

The origin is situated posterior to the axillary artery.

Course and relations

It passes behind the first part of the axillary artery, curves forward between the axillary artery and vein, and unites in front of the artery with a filament from the lateral nerve.

It then enters the deep surface of the pectoralis minor muscle, where it divides into a number of branches, which supply the muscle.

Two or three branches pierce the muscle and end in the sternocostal head of the pectoralis major muscle. The medial pectoral nerve pierces both the pectoralis minor and the sternocostal head of the pectoralis major. The lateral pectoral nerve pierces only the clavicular head of the pectoralis major.