Medial Pectoral Nerve

Written by Atilla Emin

Last updated September 18, 2023 • 13 Revisions •

The medial pectoral nerve is a motor nerve arising from the medial cord of the brachial plexus.

It supplies motor innervation to the pectoralis minor and the sternocostal head of pectoralis major.

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Course

The medial pectoral nerve originates from the medial cord of the brachial plexus, containing fibres from C8 and T1.

It arises posterior to the first part of the axillary artery, before passing medially to the second part of the artery.

It then runs anteriorly between the axillary artery and vein, where it commonly recieves a branch of the lateral pectoral nerve to form a nerve loop (ansa pectoralis).

From here, it penetrates the pectoralis minor muscle, providing motor innervation. Some fibres continue through the muscle to supply the lower portion of the sternocostal head of the pectoralis major.

Fig 1
Medial and lateral pectoral nerves.

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Motor Functions

The medial pectoral nerve suppies motor innervation to both:

  • Pectoralis minor
  • Pectoralis major (sternocostal head)

Fig 2
The sternal and clavicular heads of the pectoralis major.

Fig 3
The serratus anterior and pectoralis minor muscles.