Large arteries of ( thorax , abdomen & L.L )

2026

Large Arteries: Thorax, Abdomen, and Pelvis – Exam-Focused Notes

Introduction: Definition and Overview of Major Arteries

Heart Structure

• Heart consists of two atria and two ventricles.

Major Arteries Arising from Thorax

• Ascending Aorta (originates from Left Atrium per source).
• Arch of Aorta.
• Descending Aorta.
• Pulmonary Trunk.

Definition of Vessels (Exam Point)

• Any vessel exiting the heart = Artery.
• Any vessel entering the heart = Vein.

Pulmonary Trunk

• Is an artery despite carrying deoxygenated blood.
• Origin: Right Ventricle.
• Division: Divides into Right and Left pulmonary branches.

Aorta Continuation

• Aorta continues as Abdominal Aorta in the abdomen.

Abdominal Aorta Course

• Begins: At diaphragm at lower border of T12.
• Terminates: At lower border of L4.

Termination of Abdominal Aorta

• At L4, divides into Common Iliac Arteries (Right and Left).

Common Iliac Artery Division

• External Iliac Artery: Continues into lower limb as Femoral Artery.
• Internal Iliac Artery: Enters the pelvis.

Lecture Scope

• Covers aorta and major branches down to:
• • Common Iliac Arteries
  • External Iliac Arteries
  • Internal Iliac Arteries
  • Specific lower limb arteries (e.g., Popliteal Artery)

Pulmonary Trunk

Origin (Exam Point)

• Arises from smooth part of Right Ventricle.
• Specifically from the Infundibulum (or Conus Arteriosus).

Direction/Course

• Travels upward, backward, and to the left.

Length

• Approximately 5 cm.

Termination

• Ends beneath the Arch of Aorta.
• Divides into Right and Left Pulmonary Arteries.

Pulmonary Valve

• Location: Left Third Costochondral Junction (union of costal cartilage and rib bone).
• Auscultation Site (Exam Point): Valve closure sound heard at Left Second Intercostal Space (corresponds to leftward direction of artery).

Comparison: Right vs. Left Pulmonary Arteries

FeatureRight Pulmonary ArteryLeft Pulmonary Artery

Length/Diameter

Longer and Wider

Shorter and Narrower

Course

Passes posterior to Ascending Aorta and Trachea to reach Right Lung

Shorter course (closer to Left Lung)

Division

Divides into two branches before entering lung

Divides into two branches

Branch Supply

Superior branch → Superior Lobe<br>Inferior branch → Middle + Inferior Lobes

One branch → Superior Lobe<br>One branch → Inferior Lobe

Relation (Arch)

Superior to Arch of Azygos Vein

Passes beneath Arch of Aorta

Relations of Pulmonary Arteries

Right Pulmonary Artery Relations

• Anterior:
• • Ascending Aorta
  • Superior Vena Cava (SVC)
  • Vagus Nerve
  • Phrenic Nerve
• Posterior:
• • Right Bronchus
  • Azygos Vein

Left Pulmonary Artery Relations

• Anterior:
• • Vagus Nerve
  • Phrenic Nerve
• Posterior:
• • Left Bronchus
  • Esophagus
  • Descending Aorta

Ascending Aorta

Origin (Exam Point)

• Starts in Left Ventricle.
• Arises from Aortic Vestibule (smooth part of Left Ventricle).

Direction/Course

• Travels upward, backward, and to the right.

Start and End Points

• Starts: Left Third Intercostal Space.
• Ends: Right Second Costal Cartilage.

Aortic Valve

• Location: Left Third Intercostal Space.
• Auscultation Site (Exam Point): Valve closure sound heard at Right Second Intercostal Space.

Aortic Sinuses and Branches

Aortic Sinuses

• Three swellings at base of aorta = Aortic Sinuses.
• Located above the three cusps of Aortic Valve.

Cusp Configuration

• One anterior cusp.
• Two posterior cusps.

Branches (Exam Point)

• Ascending Aorta gives two branches:
• 1. Right Coronary Artery: Arises from Anterior Aortic Sinus.
  2. Left Coronary Artery: Arises from Left Posterior Aortic Sinus.

Arch of Aorta (Aortic Arch)

Start Point

• Begins at end of Ascending Aorta.

Location (Exam Point)

• Starts at level of Right Second Costal Cartilage.
• Corresponds to Sternal Angle.
• Vertebral level: approximately T4.

Shape

• Convex superiorly (above).
• Concave inferiorly (below) (Exam Point).

Course

• Curves from right to left.
• Also curves from anterior to posterior.

End Point

• Ends posteriorly at level of T4.

Relations of Arch of Aorta

Anterior Relations (Anterior and Left)

• Vagus Nerve
• Phrenic Nerve
• Thymus Gland

Inferior Relations (Structures Passing Under Arch)

• Left Pulmonary Artery (left branch of Pulmonary Trunk).
• Ligamentum Arteriosum:
• • Connects Left Pulmonary branch to Arch.
  • Mechanism: Fibrous remnant of Ductus Arteriosus in fetus.
  • Function in fetus: Shunts blood away from non-functional lungs back into systemic circulation.
• Superficial Cardiac Plexus.
• Left Recurrent Laryngeal Nerve:
• • Given off by Left Vagus Nerve.
  • Passes under the Arch.

Posterior Relations (Posterior and Right)

• Esophagus
• Trachea
• Left Recurrent Laryngeal Nerve (as it returns superiorly)

Branches of Arch of Aorta

Three Major Branches (Exam Point)

1. Brachiocephalic Artery (Brachiocephalic Trunk):
2. • Divides into:
   • • Right Common Carotid Artery
     • Right Subclavian Artery
2. Left Common Carotid Artery:
3. • Arises directly from Arch.
3. Left Subclavian Artery:
4. • Arises directly from Arch.

Variant Fourth Branch

• Thyroidea Ima Artery:
• • May sometimes be present.
  • Arises from Arch.
  • Supplies Thyroid Gland.

Superior Relations

• The three major branches
• Left Brachiocephalic Vein

Descending Thoracic Aorta

Start and End Points

• Starts: T4.
• Ends: T12 (passes through Aortic Opening of Diaphragm).

Course

• Begins on left side of Vertebral Column.
• At T7: Curves to descend anterior to Vertebral Column.
• Esophagus shift: Previously midline, shifts to left side around T7 as aorta shifts position.

Branches of Descending Thoracic Aorta

Parietal Branches (to Body Wall)

1. Posterior Intercostal Arteries:
2. • Supply spaces 3 to 11.
2. Subcostal Artery:
3. • Supplies 12th space (below 12th rib).
3. Superior Phrenic Arteries:
4. • Right and Left branches.
   • Supply superior surface of Diaphragm.

Visceral Branches (to Mediastinal Contents)

1. Bronchial Branches:
2. • Left Bronchial Arteries: Arise directly from Descending Aorta.
   • Right Bronchial Artery: Arises from Right Third Posterior Intercostal Artery.
2. Esophageal Branches.
3. Pericardial Branches:
4. • Supply Fibrous Pericardium.
   • Supply Parietal layer of Serous Pericardium.

🩺 Abdominal Aorta

Start and End Points

• Starts: Lower border of T12 (Aortic Opening of Diaphragm).
• Ends: Lower border of L4.

Termination

• Divides into Right and Left Common Iliac Arteries.

Position

• Runs anterior to Vertebral Column.

Shift

• Inferior Vena Cava (IVC) displaces lower part of Aorta to left side of vertebral column.
• Consequence: Right Common Iliac Artery is longer than Left Common Iliac Artery.

Branches of Abdominal Aorta

Classification: Single (Unpaired) vs. Paired

Single/Unpaired Branches (Four Total)

Arise from anterior aspect (except Median Sacral)

1. Celiac Trunk:
2. • Supplies Foregut structures.
   • Includes: stomach, liver, upper duodenum, lower esophagus.
2. Superior Mesenteric Artery:
3. • Supplies Midgut.
3. Inferior Mesenteric Artery:
4. • Supplies Hindgut.
4. Median Sacral Artery:
5. • Arises from posterior aspect of Aorta.

Paired Branches

1. Inferior Phrenic Arteries.
2. Middle Suprarenal Arteries:
3. • Supply Suprarenal Gland.
   • Arise directly from aorta.
3. Renal Arteries.
4. Gonadal Arteries:
5. • Supply gonads (Testes or Ovaries).
5. Lumbar Arteries:
6. • Four branches on right.
   • Four branches on left.
   • Supply muscles and posterior abdominal wall.
6. Terminal Branches:
7. • Right Common Iliac Artery
   • Left Common Iliac Artery

Common Iliac and External Iliac Arteries

Common Iliac Artery

Start and End

• Starts: L4.
• Ends: Opposite Sacroiliac Joint.

Division

• Divides into:
• • External Iliac Artery
  • Internal Iliac Artery

External Iliac Artery

Start and End

• Starts: Sacroiliac Joint.
• Ends: Inguinal Ligament.

Continuation (Exam Point)

• Continues into thigh as Femoral Artery.

Branches (Two Branches Inside Pelvis)

1. Deep Circumflex Iliac Artery:
2. • Travels towards Iliac Crest and Anterior Superior Iliac Spine.
   • Runs parallel to superficial version.
   • Anastomoses with Lumbar arteries.
2. Inferior Epigastric Artery:
3. • Ascends superiorly towards Umbilicus.

🏛️ Internal Iliac Artery

Function

• Supplies viscera (organs) located in pelvis.

Start

• Sacroiliac Joint.

Division (Exam Point)

• Divides into:
• • Anterior Division
  • Posterior Division

Posterior Division (Three Branches)

1. Iliolumbar Artery:
2. • Runs up to anastomose with Lumbar Arteries.
2. Lateral Sacral Artery:
3. • Runs down lateral side of Sacrum.
   • Enters Sacral Foramina.
   • Supplies contents of Sacral Canal.
3. Superior Gluteal Artery:
4. • Exits pelvis via Greater Sciatic Foramen.
   • Supplies Gluteal Region.

Anterior Division (Visceral and Parietal Branches)

Supplies remaining structures and organs in pelvis

Vesical/Genital Branches

In Males:

• Superior Vesical Artery: Supplies superior bladder surface.
• Inferior Vesical Artery: Supplies prostate and inferior bladder surface.

In Females:

• Inferior Vesical Artery replaced by Vaginal Artery.

Other Anterior Division Branches

• Uterine Artery (in females):
• • Runs along lateral wall of uterus.
  • Supplies: uterus, vagina, fallopian tube.
  • Forms anastomoses.
• Inferior Gluteal Artery:
• • Exits via Greater Sciatic Foramen to Gluteal Region.
• Internal Pudendal Artery:
• • Supplies external genitalia.
  • Contrast: External Pudendal Artery (Superficial External Pudendal) also supplies external genitalia but is a branch of Femoral Artery.
• Obturator Artery:
• • Supplies medial side of thigh.
  • Last branch mentioned.

Anterior Division Branches Summary (Exam Point)

• Superior Vesical
• Inferior Vesical (or Vaginal in females)
• Uterine
• Inferior Gluteal
• Internal Pudendal
• Obturator