Trunk (thorax, abdomen, back)

Breastbone

Sternum

Origin

Consists of manubrium, body, and xiphoid process; articulates with clavicles and costal cartilages I–VII

Insertion

Attachment site for pectoralis major, sternocleidomastoid, rectus abdominis, and diaphragm

Function

Protects heart, mediastinal great vessels, and lungs; anchors the anterior thoracic cage

Innervation

Intercostal nerves (T1–T6)

Movement & chain

Moves with pump-handle motion during respiration to increase anterior-posterior chest diameter

Palpation

Suprasternal notch, sternal angle of Louis (T4/T5 level, 2nd rib landmark), and xiphoid process are readily palpable

Clinical

Sternal fracture from direct blunt chest trauma (steering wheel injury); median sternotomy in cardiac surgery; bone marrow aspiration

Segmental innervation

T1–T6

In clinical practice

Anatomical target for chest compressions in cardiopulmonary resuscitation (CPR)

Region in the model

Trunk (thorax, abdomen, back)