Upper Limb Arterial Supply and Aorta Anatomy

Arterial Supply of the Upper Limb

• The Upper Limb's arterial supply begins with the great vessels of the aortic arch
• The aortic arch typically branches into the left subclavian artery, the left common carotid artery, and the brachiocephalic trunk (which divides into the right common carotid and right subclavian arteries)

Anatomical Variations Warning

• Anatomical models and textbooks might contain variations or errors
• One example of a possible anatomical variation is a model which depicts two brachiocephalic trunks
• Potential inaccuracies can be avoided by consulting multiple reference materials

Aorta and Initial Branches

• The aorta exits the heart's left ventricle, and arches towards the left and posteriorly
• It has three initial branches: the brachiocephalic trunk, left common carotid artery, and left subclavian artery
• The common carotid arteries provide blood to the head
• The brachiocephalic trunk bifurcates into the right subclavian and right common carotid arteries

Subclavian Artery

• The subclavian artery has the vertebral artery as a branch and continues into the Upper Limb
• The vertebral artery runs through the transverse foramina of the vertebrae and enters the skull to supply the brain
• The subclavian artery becomes the axillary artery in the axilla (armpit), after passing the first rib

Axillary Artery

• The axillary artery is susceptible to injury
• The brachial plexus surrounds it, with parts named in relation to the artery's position
• The pectoralis minor muscle divides the axillary artery into three parts: first, second, and third
  • The first part gives off one branch
  • The second part gives off two branches
  • The third part gives off three branches

Branches of the Axillary Artery

• The first part gives off the superior thoracic artery, which supplies the superior thoracic region
• The second part gives off the lateral thoracic artery, which supplies the lateral thorax
  • The thoracoacromial artery supplies the thorax and acromion, branching around the scapula
• The third part gives off the subscapular artery, to the subscapular region
  • Also the anterior and posterior circumflex humeral arteries, which encircle the humerus

Anastomoses at Joints

• Arterial branches and anastomoses are abundant around joints, like the shoulder and elbow
• Anastomoses are interconnections between arteries
• Collateral circulation allows blood supply to the limb even if one artery is blocked through alternative routes
• If the axillary artery is impeded, blood can flow around the shoulder through alternate arteries

Brachial Artery

• The axillary artery becomes the brachial artery after passing teres major
• The brachial artery runs with branches of the brachial plexus, including the ulnar and median nerves
• It lies superficially in the groove between the biceps and triceps muscles

Radial and Ulnar Arteries

• The brachial artery divides into the radial and ulnar arteries in the cubital fossa at the elbow
• The radial artery is on the thumb side
• The ulnar artery travels deep within the forearm, running with the ulnar nerve

Arteries of the Forearm

• The ulnar artery has interosseous branches that supply blood to the posterior compartment (extensors) and deep muscles
• Recurrent and interosseous branches connect arteries around the elbow, establishing collateral circulation
• The recurrent arteries also ensure collateral circulation, by running back up to the elbow

Arteries at the Wrist

• The ulnar artery becomes superficial near the wrist, passing over the flexor retinaculum along with the ulnar nerve
• The radial artery passes through the anatomical snuffbox around the thumb
• Arteries are exposed and at risk at the wrist

Arterial Arches of the Hand

• The radial and ulnar arteries connect in the hand, creating superficial and deep palmar arches
• These arches supply digital branches, delivering blood to the muscles and tissues of the hand
• This system ensures robust blood supply to the Upper Limb and hand

Hemorrhage Control

• The arteries are well-protected, and bleeding control involves pressure if there is a deep cut in the hand
• If bleeding is difficult to control with direct pressure, compression of the brachial artery may be needed to limit arterial blood flow to the hand
• In extreme cases, tourniquet application should be considered, and released regularly
• Anatomical knowledge will assist with bleeding from a major artery in the Upper Limb