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

[1] 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.

[1][2] It is derived from the eighth cervical (C8) and first thoracic (T1) spinal nerve roots.

[3] The lateral pectoral nerve pierces only the clavicular head of the pectoralis major.

[5] This article incorporates text in the public domain from page 933 of the 20th edition of Gray's Anatomy (1918)