Overview
This lecture introduces the arterial supply to the upper limb, focusing on the anatomy, divisions, and main branches of the subclavian artery, including key imaging perspectives and common anatomical variations.
Subclavian Artery Origin and Course
- The right subclavian artery arises from the brachiocephalic trunk, while the left comes directly off the aortic arch.
- The subclavian artery is divided into three parts by the first rib and the anterior scalene muscle.
- The first part lies medial to the anterior scalene; the second is posterior to it; the third extends from the lateral border of the scalene to the lateral border of the first rib.
- At the lateral border of the first rib, the subclavian artery becomes the axillary artery.
Main Branches of the Subclavian Artery
- Four primary branches (medial to lateral): vertebral artery, internal thoracic artery, thyrocervical trunk, and costocervical trunk.
- The vertebral artery ascends through cervical transverse foramina to form the basilar artery.
- The internal thoracic artery descends into the thorax along the anterior chest wall.
- The thyrocervical trunk gives off the inferior thyroid, ascending cervical, suprascapular, and sometimes superficial cervical arteries.
- The costocervical trunk gives off the supreme intercostal artery (to first and second ribs) and deep cervical artery (to the deep neck).
Key Anatomical Variations and Imaging
- Branches may vary: dorsal scapular and superficial cervical arteries may originate directly from the subclavian or from branches.
- Use sagittal, coronal, and axial CT views to identify branches; knowledge of rib and scalene anatomy aids identification.
- Variations are common, so tracing distal arteries back to their origin is important in imaging.
- Subclavian artery anatomy is clinically relevant due to its vulnerability at the thoracic inlet.
Key Terms & Definitions
- Subclavian artery — main artery supplying blood to the upper limb, divided into three parts.
- Anterior scalene muscle — neck muscle used as a landmark for dividing the subclavian artery.
- Axillary artery — continuation of the subclavian artery past the first rib.
- Vertebral artery — branch ascending to supply the brain.
- Internal thoracic artery — branch running down the chest wall.
- Thyrocervical trunk — anterior branch giving several neck and shoulder arteries.
- Costocervical trunk — posterior branch supplying the upper ribs and deep neck.
- Basilar artery — artery formed by the joining of the vertebral arteries at the base of the brain.
Action Items / Next Steps
- Review diagrams and imaging (CTA) of the subclavian artery and its branches.
- Prepare for the next lecture on the axillary artery.
- Study the relationship between the subclavian artery, anterior scalene, and first rib for exams.