Chest muscles

The muscles of the chest are divided into superficial (connecting the chest with the upper limb) and deep (the proper muscles of the chest wall involved in breathing). Together they provide arm movement, breathing, and protection for the thoracic organs.

Pectoralis major muscle

Pectoralis major (m. pectoralis major) is the largest and most powerful muscle of the anterior wall of the chest.

Start (three parts):

• Clavicular part - from the medial half of the clavicle
• Sternal-costal part - from the sternum and cartilage of the II–VI ribs
• Abdominal part - from the anterior wall of the vagina of the rectus abdominis muscle

Attachment: crest of the greater tubercle of the humerus.

Features:

• Bringing the arm to the body
• Shoulder internal rotation
• Shoulder flexion (clavicular part)
• With a fixed arm - pulling up the torso (pull-ups)

Innervation: medial and lateral pectoral nerves (C5–Th1).

Pectoralis minor muscle

Pectoralis minor (m. pectoralis minor) is located under the pectoralis major.

Beginning: III–V ribs. Attachment: coracoid process of the scapula. Functions: pulls the scapula forward and down, when the scapula is fixed, raises the ribs (auxiliary muscle of inhalation).

Between the pectoralis minor muscle and the ribs there are vessels and nerves of the brachial plexus - this is important for surgical approaches.

Serratus anterior muscle

Serratus anterior (m. serratus anterior) is a broad muscle on the lateral wall of the chest.

Beginning: ribs I–IX (teeth). Insertion: medial border and inferior angle of the scapula. Function: “presses” the scapula to the chest, rotates the scapula when raising the arm above the horizontal.

Serratus anterior palsy (damage to the long thoracic nerve) results in "pterygoid scapula" - the scapula lags behind the rib cage.

Intercostal muscles

External intercostal (11 pairs) - fibers go from top to bottom and forward. Raise the ribs → inhale.

Internal intercostal (11 pairs) - fibers go from top to bottom and back. Lower the ribs → exhale.

The innermost intercostals are a deep layer; intercostal vessels and nerves pass between them. When puncturing the pleural cavity, the needle is inserted along the upper edge of the rib so as not to damage the neurovascular bundle located at the lower edge.

Subclavius muscle

Subclavian (m. subclavius) is a small muscle between the collarbone and the first rib. Depresses the clavicle and protects the subclavian vessels during a clavicle fracture.

Clinical significance

Knowledge of the anatomy of the chest muscles is necessary:

• For surgeons - during mammoplasty, the implant is placed under or above the pectoralis major muscle
• Resuscitators - for the correct technique of chest compressions during CPR
• Sports physicians - rupture of the pectoralis major muscle occurs in athletes when bench pressing with heavy weights

In the free 3D atlas Humio, you can view the pectoralis major, pectoralis minor and intercostal muscles layer by layer - rotate the model and study the attachments of each muscle.