The pectoralis major is a thick, fan-shaped muscle, situated at the chest of the human body.

The pectoralis major muscle has three parts:

• Clavicular part;
• Sternocostal part;
• Abdominal part.

Origin: clavicular part - anterior surface of clavicula (medial half); sternocostal part - anterior surface of sternum, the six costal cartilages; abdominal part - the anterior layer of the rectus sheath.

Insertion: greater tubercle of humerus / anteromedial proximal part of the humerus.

Function: adduction and anteversion of the upper arm (in the shoulder joint), medial rotation of the arm, retroversion of the arm. The antagonist muscle of the pectoralis major is the deltoid muscle.

Innervation: medial and lateral pectoral nerve - branches of the brachial plexus; the innervation for the clavicular part arises from the spinal segments C5 and C6, while for the sternocostal part - from the C7, C6 and T1.