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    From Cardiovascular System

    Radial Arteries
    Supply the lateral aspect of the forearm and hand.
    External Jugular Veins
    Drain blood from the face and scalp.
    Great Cardiac Vein
    Drains blood from the anterior surface of the heart.
    Superior Vena Cava
    Returns deoxygenated blood from upper body.
    Subclavian Veins
    Carry blood from the upper limbs to the heart.
    Abdominal Aorta
    Part of descending aorta within the abdomen.
    Cephalic Veins
    Superficial veins of the lateral upper limb.
    Anterior Interventricular Branch
    Supplies anterior interventricular septum (LAD).
    External Iliac Arteries
    Continue into the legs as femoral arteries.
    Internal Iliac Veins
    Drain pelvic organs.
    Fossa Ovalis
    Remnant of the fetal foramen ovale.
    Dorsalis Pedis Arteries
    Supply blood to the dorsal surface of the foot.
    Basilic Veins
    Superficial veins of the medial upper limb.
    Popliteal Veins
    Drain blood from the knee region.
    Fibrous Pericardium
    Outer layer of the pericardium made of dense connective tissue.
    Small Saphenous Vein
    Superficial vein of the posterior leg.
    Brachiocephalic Trunk
    First major branch off the aortic arch.
    Right Pulmonary Artery
    Carries blood to right lung.
    Heart
    Muscular organ responsible for pumping blood throughout the body.
    Circumflex Branch
    Curves around to the posterior heart.
    Right Ventricle
    Pumps blood to the lungs via pulmonary artery.
    Left Atrium
    Receives oxygenated blood from the lungs.
    Left Superior Pulmonary Vein
    Returns oxygenated blood from left lung.
    Aortic Valve
    Valve between left ventricle and aorta.
    External Carotid Artery
    Supplies blood to the face and scalp.

    Pulmonary Trunk

    Reviewed by our medical team

    Carries deoxygenated blood from right ventricle to lungs.

    Overview

    The pulmonary trunk is a large arterial vessel that emerges from the right ventricle of the heart and serves as the main conduit for deoxygenated blood being transported to the lungs for oxygenation. It is the first component of the pulmonary circulation and quickly bifurcates into the right and left pulmonary arteries. Unlike most arteries that carry oxygen-rich blood, the pulmonary trunk and its branches carry oxygen-poor blood — a unique feature of the pulmonary vascular system.

    Location

    The pulmonary trunk originates from the right ventricle of the heart and ascends slightly posteriorly and to the left. It lies:

    • Anterior to the ascending aorta at its origin

    • Left of the aorta as it ascends

    • Below the aortic arch before it bifurcates

    At the level of the T5–T6 vertebrae (around the sternal angle), it bifurcates into:

    • Right pulmonary artery – passes horizontally across the midline to the right lung

    • Left pulmonary artery – passes horizontally to the left lung

    Structure

    The pulmonary trunk is a thick-walled, elastic artery designed to accommodate large volumes of blood ejected from the right ventricle during systole. Key structural features include:

    • Origin: Conus arteriosus (infundibulum) of the right ventricle

    • Length: Approximately 5 cm

    • Diameter: Roughly 3 cm in adults

    • Wall layers: Tunica intima (endothelium), tunica media (smooth muscle and elastic fibers), and tunica adventitia (connective tissue)

    • Pulmonary valve: A semilunar valve located at the origin of the trunk, preventing backflow into the right ventricle during diastole

    Function

    The primary function of the pulmonary trunk is to:

    • Transport deoxygenated blood from the right ventricle to the lungs via the pulmonary arteries

    • Serve as the starting point of the pulmonary circulation

    This ensures that blood is directed toward the alveolar capillaries in the lungs, where gas exchange occurs — carbon dioxide is released, and oxygen is absorbed.

    Physiological Role(s)

    The pulmonary trunk plays multiple vital roles in cardiovascular physiology:

    • Manages low-pressure, high-volume flow: Unlike systemic arteries, the pulmonary trunk operates under lower pressure (normally 15–25 mmHg systolic) to protect the delicate pulmonary capillaries.

    • Supports gas exchange: It ensures timely delivery of blood to the lungs for continuous oxygenation and carbon dioxide removal.

    • Coordinates with cardiac cycle: The pulmonary valve and elastic nature of the trunk allow smooth systolic ejection and diastolic closure, minimizing energy loss.

    Clinical Significance

    The pulmonary trunk is involved in various congenital, structural, and hemodynamic disorders:

    • Pulmonary Hypertension: Elevated pressure in the pulmonary trunk and its branches can result from chronic lung disease, left heart disease, or idiopathic causes. Leads to right ventricular strain and eventual failure.

    • Pulmonary Embolism: A life-threatening condition where a thrombus lodges in the pulmonary trunk or its branches, causing acute right heart failure, hypoxia, or death.

    • Truncus Arteriosus: A rare congenital defect where the pulmonary trunk and aorta fail to separate during development, resulting in a single outflow tract — requires early surgical correction.

    • Transposition of the Great Arteries (TGA): A condition in which the pulmonary trunk arises from the left ventricle instead of the right, disrupting normal circulation and requiring neonatal intervention.

    • Dilation or Aneurysm: Pulmonary trunk dilatation may occur in pulmonary hypertension or connective tissue disorders and is visible on imaging studies (CT, MRI, echocardiography).

    • Valve Disorders: Pulmonary valve stenosis or regurgitation affects flow through the trunk and may lead to post-stenotic dilation or backward flow into the right ventricle.

    Assessment of the pulmonary trunk is routinely performed using echocardiography, CT angiography, and cardiac MRI. Early recognition of abnormalities is critical for preventing right-sided heart failure and improving outcomes in cardiopulmonary disease.

    Did you know? The human heart beats about 70 to 75 times per minute in a resting state.