The pectoral region is the anterior region of the upper chest where there are four thoracoappendicular muscles (also known as the pectoral muscles):
pectoralis major
pectoralis minor
subclavius
serratus anterior
The breast is located superficial to the muscles. The lateral border of the pectoralis major muscle forms the anterior margin of the axilla. At the superolateral aspect the pectoral region is separated from the deltoid muscle by the deltopectoral groove and contains the cephalic vein.
What organs are in the pectoral region?
The chest is the area of origin for many of the body's systems as it houses organs such as the heart, esophagus, trachea, lungs, and thoracic diaphragm. The circulatory system does most of its work inside the chest.
The pectoral region is located on the anterior chest wall. It contains four muscles that exert a force on the upper limb: the pectoralis major, pectoralis minor, serratus anterior and subclavius.
In this article, we shall look at the anatomy of the muscles of the pectoral region – their attachments, actions and innervation.
Pectoralis Major
The pectoralis major is the most superficial muscle in the pectoral region. It is large and fan shaped, and is composed of a sternal head and a clavicular head:
Attachments: The distal attachment of both heads is into the intertubercular sulcus of the humerus.
Clavicular head – originates from the anterior surface of the medial clavicle.
Sternocostal head – originates from the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle.
Function: Adducts and medially rotates the upper limb and draws the scapula anteroinferiorly. The clavicular head also acts individually to flex the upper limb.
Innervation: Lateral and medial pectoral nerves.
By TeachMeSeries Ltd (2021)
Fig 1 - The sternal and clavicular heads of the pectoralis major.
Fig 1 – The sternal and clavicular heads of the pectoralis major.
Pectoralis Minor
The pectoralis minor lies underneath its larger counterpart muscle, pectoralis major. Both muscles form part of the anterior wall of the axilla region.
Attachments: Originates from the 3rd-5th ribs and inserts into the coracoid process of the scapula.
Function: Stabilises the scapula by drawing it anteroinferiorly against the thoracic wall.
Innervation: Medial pectoral nerve.
