Anatomy of Great Blood Vessels of Thorax

Thoracic Blood Vessels Anatomy

• Learning Objectives: Describe anatomical details and clinical correlates of thoracic aorta, pulmonary trunk, brachiocephalic veins, superior vena cava (SVC), and inferior vena cava (IVC).

Ascending Aorta

• Located within the pericardial sac, surrounded by the pulmonary trunk.
• Originates at the aortic orifice, near the 3rd left costal cartilage, posterior to the sternum.
• Ascends slightly right, reaching the 2nd right costal cartilage before becoming the arch of the aorta.
• Displays three bulges (aortic sinuses) above the aortic valve, from which right and left coronary arteries originate.

Arch of Aorta

• Begins where the ascending aorta exits the pericardial sac, courses upward, backward, and left.
• Ends at the lower border of vertebra T4, positioned anteriorly initially then left of the trachea.
• Branches:
  • Brachiocephalic trunk: Divides into right common carotid and right subclavian arteries, supplying the right head, neck, and upper limb.
  • Left common carotid artery: Supplies the left head and neck.
  • Left subclavian artery: Supplies the left upper limb.
• Thyroid ima artery: May arise from the brachiocephalic trunk or aortic arch, supplying the thyroid gland.

Ligamentum Arteriosum

• A fibrous band connecting the left pulmonary artery and the arch of the aorta; originates from the embryonic ductus arteriosus.
• Important for circulatory changes at birth, as it closes postnatally.

Descending Thoracic Aorta

• Begins at the lower border of T4, continuous with the arch, and ends at T12 while passing through the diaphragm.
• Positioned to the left of the vertebral column, approaches midline, lies anterior to lower thoracic vertebral bodies.
• Gives off multiple branches during its course.

Coarctation of Aorta

• Clinical manifestation: Discrepancy in pressure between brachial (increased) and femoral (decreased) arteries due to narrowing of the aorta.

Pulmonary Trunk

• Approximately 5 cm long, originating from the right ventricle behind the 3rd left costal cartilage.
• Divides into right and left pulmonary arteries at the concavity of the aortic arch.
• Has three sinuses above valve cusps.

Branches of the Pulmonary Trunk

• Right pulmonary artery: Longer, larger, runs behind the ascending aorta.
• Left pulmonary artery: Connects to the aortic arch via the ligamentum arteriosum.

Brachiocephalic Veins

• Formed by the union of internal jugular and subclavian veins near the clavicle; both veins drain into the SVC.
• Right brachiocephalic vein: Shorter with a vertical course.
• Left brachiocephalic vein: Longer with an oblique course crossing anteriorly to aortic arch branches.

Superior Vena Cava (SVC)

• A large venous channel (7 cm) collecting blood from the upper body, draining into the right atrium.
• Formed by right and left brachiocephalic veins; pierces pericardium at the 2nd right costal cartilage.
• No valves present, located in the superior mediastinum.

Tributaries of the SVC

• Includes right and left brachiocephalic veins and the azygos vein, which opens into the SVC near the 2nd right costal cartilage.

Inferior Vena Cava (IVC)

• Short intrathoracic part (0.5 inch), lies within the pericardium.
• Pierces the diaphragm at T8, entering the right atrium one inch right of the midline.
• No valves present, parallel relations to right phrenic nerve, lung, and pleura.

Case Problem

• Clinical scenario depicting a 61-year-old man with potential complications related to cardiovascular health and history of penile ulcer, assessing risk of specific complications such as thoracic aorta aneurysm.