Upper limb
Pectoralis Major, Abdominal Head
Musculus pectoralis major (pars abdominalis)
- Origin
- Anterior layer of the aponeurosis of the external oblique abdominis muscle
- Insertion
- Crest of the greater tubercle of the humerus, together with the other heads
- Function
- Depression of the arm and support of adduction; the smallest of the three heads
- Innervation
- Medial and lateral pectoral nerves, C6-T1
- Movement & chain
- Synergist with sternocostal head during forceful downward and inward arm adduction (chopping, swimming).
- Palpation
- Palpable along the inferolateral border of the pectoralis major blending into the anterior rectus sheath.
- Clinical
- Forms the lowest border of the anterior axillary fold; its tendon fibers twist 180 degrees before inserting onto the humerus.
- Segmental innervation
- Myotome C6-T1.
- In clinical practice
- Wound management post-laparotomy/chest drain and abdominal wall monitoring; support incision site during coughing to prevent wound dehiscence.
- Region in the model
- Upper limb