Blood Supply: Upper Extremity

Question 1

ARTERIES

Answer 1

• The arterial supply to the upper limb begins in the chest as the subclavian artery. The right subclavian artery arises from the brachiocephalic trunk, while the left subclavian branches directly off the arch of aorta.
• When the subclavian arteries cross the lateral edge of the lst rib, they enter the axilla, and are called axillary arteries.

Question 2

In the Axilla

Answer 2

• The axillary artery passes through the axilla, just underneath the pectoralis minor muscle, enclosed in the axillary sheath.
• At the level of the humeral surgical neck, the posterior and anterior circumflex humeral arteries arise.
• They circle posteriorly around the humerus to supply the shoulder region. The largest branch of the axillary artery also arises here - the subscapular artery.
• The axillary artery becomes the brachial artery at the level of the teres major muscle.

Question 3

In the Upper Arm

Answer 3

• When the axillary artery reaches the lower border of the teres major, it becomes the brachial artery.
• The brachial artery is the main source of blood for the arm.
• Immediately distal to the teres major, the brachial artery gives rise to the profunda brachii (deep artery). It travels with the radial nerve within the radial groove of the humerus, and supplies structures in the posterior aspect of the upper arm (e.g. triceps brachii). The profunda brachii terminates by contributing to an anastomotic network around the elbow joint.
  along the posterior surface of the humerus, running in the radial groove. It supplies structures in the posterior aspect of the arm (e.g. triceps brachii), and terminates by contributing to a network of vessels at the elbow joint.
• The brachial artery descends down the arm immediately posterior to the median nerve. As it crosses the cubital fossa, underneath the brachialis muscle, the brachial artery terminates by bifurcating into the radial and ulnar arteries.

Question 4

In the Forearm

Answer 4

In the distal region of the cubital fossa, the brachial artery bifurcates into the radial artery and the ulnar artery. The radial artery supplies the posterior aspect of the forearm and the ulnar artery supplies the anterior aspect. The two arteries anastomose in the hand, by forming two arches, the superficial palmar arch, and the deep palmar arch.

Question 5

In the Hand

Answer 5

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  from which branches to the digits emerge.

• Racial artery - contributes mainly to supply of the thumb and the lateral side of the index finger

Ulnar artery - contributes mainly to the supply of the rest of the digits, and the medial side of the index finger

• the ulnar artery moves into the hand anteriorly to the flexor retinaculum, and laterally to the ulmar neane, In the hand, it divides into two branches, the superficial palmar arch, and the deep palmar branch
• from the superficial palmar arch, common palmar digital arteries arise, supplying the digits. The superficial palmar arch then anastomoses with a branch of the radial artery. The superficial palmar arch is found anteriorly to the flexor tendons in the hand, deep to the palmar aponeurosis.
• The radial artery enters the hand dorsally, crossing the floor of the anatomical snuffbox. It turns medially and moves between the heads of the adductor pollicis. The radial artery then anastomoses with the deep palmar branch of the ulnar artery, forming the deep palmar arch, which gives rise to five arteries supplying the digits.

Question 6

VEINS

Answer 6

The venous system of the upper limb drains deoxygenated blood from the upper arm, forearm and hand. It can be subdivided into the superficial system and the deep system.

Question 7

Superficial Veins

Answer 7

• The major superficial veins of the upper limb are the cephalic and basilic veins. As their name suggests, they are located within the subcutaneous tissue of the upper limb.
• The basilic vein originates from the dorsal venous network of the hand. It ascends the medial aspect of the upper limb. At the border of the teres major, the vein moves deep into the arm. Here, it combines with the brachial veins to form the axillary vein.
• The cephalic vein arises from the dorsal venous network of the hand. It ascends the antero-lateral aspect of the upper limb, passing anteriorly at the elbow. At the shoulder, the cephalic vein travels between the deltoid and pectoralis major muscles (known as the deltopectoral groove), and enters the axilla region via the clavipectoral triangle. Within the axilla, the cephalic vein terminates by joining the axillary vein.
• At the elbow, the cephalic and basilic veins are connected by the median cubital vein.

Question 8

Deep Veins

Answer 8

• The deep veins of the upper limb are situated underneath the deep fascia.
• They are paired veins that accompany and lie either side of an artery. The brachial veins are the largest in size, and are situated either side of the brachial artery. The pulsations of the brachial artery assist the venous return. Veins that are structured in this way are known as vena comitantes.
• Perforating veins run between the deep and superficial veins of the upper limb, connecting the two systems.