Upper limb arterial supply

Arterial Supply of the Upper Limb

• Begins at the arch of the aorta with three major arteries arising from it.
• Left subclavian artery supplies the left upper limb.
• Left common carotid artery supplies the head and neck.
• Brachiocephalic trunk (previously known as the innominate artery) serves the right side.
• The brachiocephalic trunk splits into the right common carotid and right subclavian arteries.
• Anatomical variations can occur, such as having two brachiocephalic trunks, highlighting that anatomical sources are not infallible.
• It is important to cross-reference multiple sources of information to identify errors and variations.
• Simplifying anatomical information may omit detail but is useful for learning essential facts.

Path of Arteries to the Upper Limb

• The aorta exits the left ventricle, arches to the left, and curls posteriorly into the thorax.
• The arch of the aorta branches into the brachiocephalic trunk, left common carotid, and left subclavian arteries.
• The common carotid arteries ascend the neck to supply the head.
• The brachiocephalic trunk divides into the right subclavian artery and right common carotid artery.
• The anterior scalene muscle runs towards the rib in a gap, with the subclavian artery playing a role.
• The subclavian artery sends off the vertebral artery.
• The vertebral artery ascends through the transverse foramina of the vertebrae into the skull, supplying blood to the brain.
• As the subclavian artery crosses the first rib, it becomes the axillary artery in the axilla (armpit).

Axillary Artery

• The axillary artery runs through the axilla, surrounded by the brachial plexus.
• Injury to the axilla can damage the axillary artery and brachial plexus.
• The brachial plexus parts are named relative to their position around the axillary artery.
• The pectoralis minor muscle covers part of the axillary artery, dividing it into three segments.
• The first part of the axillary artery extends from the first rib to the border of pectoralis minor.
• The second part lies behind pectoralis minor.
• The third part continues beyond pectoralis minor.
• The axillary artery has one branch in its first part (superior thoracic artery), two in its second part (lateral thoracic artery and thoracoacromial artery), and three in its third part (subscapular artery, anterior circumflex humeral artery, and posterior circumflex humeral artery).
• The superior thoracic artery supplies blood to the superior thoracic region.
• The lateral thoracic artery supplies the lateral part of the thorax.
• The thoracoacromial artery supplies the thorax and acromion.
• The subscapular artery supplies the subscapular region.
• The anterior and posterior circumflex humeral arteries encircle the humerus.

Anastomoses and Collateral Circulation

• Joints like the shoulder and elbow have many arterial branches (anastomoses) for collateral circulation.
• Anastomoses are interconnections between arteries (or veins).
• Collateral circulation ensures blood supply to the limb even if one artery is occluded or severed.
• Blood vessels anastomose around the shoulder, supplying muscles and structures.
• If the auxiliary artery is blocked, blood can flow through collateral circulation around the shoulder.
• Flow may reverse direction in some arteries to maintain blood supply to the upper limb.

Brachial Artery

• As the axillary artery passes teres major, it becomes the brachial artery in the brachium (upper arm).
• The brachial artery runs with branches of the brachial plexus, including the ulnar and median nerves.
• The brachial artery is superficial in the groove between the biceps and triceps muscles.
• The brachial artery can be palpated in this groove and is fairly exposed.

Arteries of the Forearm and Hand

• At the elbow (cubital fossa), the brachial artery divides into the radial and ulnar arteries.
• The radial artery runs along the thumb side of the forearm, where the radial pulse can be felt.
• The ulnar artery runs deep within the forearm.
• The ulnar artery gives off interosseous branches that supply blood to the posterior compartment and deep muscles of the forearm.
• The radial artery passes toward the base of the thumb.
• Recurrent and interosseous branches create collateral circulation around the elbow.

Radial and Ulnar Arteries at the Wrist and Hand

• The ulnar artery becomes superficial again near the wrist, passing over the flexor retinaculum with the ulnar nerve.
• The radial artery is more superficial in the anatomical snuffbox, located around the thumb.
• The radial artery passes through the space between the thumb and first finger to enter the hand.
• The radial and ulnar arteries meet in the hand, forming the superficial palmar arch and deep palmar arch.
• These arches give off digital branches that supply blood to the digits.
• There is a rich blood supply to the upper limb and hand.

Clinical Considerations

• Deep cuts in the hand can be difficult to stop bleeding due to the extensive blood supply.
• Compressing the brachial artery may be necessary to reduce arterial pressure in the hand and stop bleeding.
• Tourniquets can be used but must be released regularly.
• Anatomical knowledge can help in managing bleeding from major arteries in the upper limb.