The anterior axio-appendicular muscles, also known as the pectoral or thoraco-appendicular muscles, include muscles in the pectoral region that control the shoulder and arm:
- Pectoralis major
- Pectoralis minor
- Subclavius
- Serratus anterior
Pectoralis major
The pectoralis major muscle is the largest and most superficial muscle of the anterior wall; it is a thick, fan-shaped muscle, covering the superior part of the thorax.
- The muscle has two heads:
- The clavicular head originates from the medial half of the clavicle.
- The sternocostal head originates from the medial part of the anterior thoracic wall (the anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle) to form:
- Lateral border: Forms most of the anterior wall of the axilla.
- Inferior border: Forms the anterior axillary fold.
- Both heads insert distally into the lateral lip of the intertubercular sulcus of the humerus.
- A narrow deltopectoral groove is formed by the pectoralis major and deltoid muscles; in which the cephalic vein runs.
- The pectoralis major muscle allows flexion, adduction, and medial rotation of the arm.
- It is innervated by the lateral and medial pectoral nerves, which originate from the brachial plexus