Lateral pectoral nerve

The lateral pectoral nerve, also known as the lateral anterior thoracic nerve, arises from the lateral cord of the brachial plexus and supplies the pectoralis major muscle.

Gross anatomy

Origin

The lateral pectoral nerve arises from the lateral cord of the brachial plexus with fibers from the fifth, sixth and seventh cervical nerves.

Course and relations

Shortly after branching from the lateral cord of the brachial plexus the lateral pectoral nerve may donate a communicating branch to the medial pectoral nerve (as shown in figure 1) forming a loop known as the ansa pectoralis, which itself branches from the medial cord of the brachial plexus. The nerve then passes inferiorly piercing the clavicopectoral fascia to pierce the deep surface of the pectoralis muscles. The ansa pectoralis runs anteriorly to the axillary artery and vein.

Branches and supply

The lateral pectoral nerve primarily supplies the pectoralis major muscle. Due to a communicating branch to the medial pectoral nerve some lateral pectoral nerve fibers pass to and innervate the pectoralis minor.

The lateral pectoral nerve also carries nociceptive and proprioceptive fibers. 

Variant anatomy

The lateral pectoral may have two distinct origins from the anterior divisions of the superior and middle trunks.

Related pathology

Selected pectoral nerve blocks can be performed either intraoperatively or preoperatively with the aid of ultrasonography and may be utilized in patients prior to breast surgery, pectoralis muscle flaps and clavicular surgery.