M01.03.038 Arterial Supply

The arterial supply to the upper limb is provided by a series of vessels that transport oxygenated blood from the heart to various regions of the arm and hand. These vessels can be categorized from proximal to distal as follows:

1. Subclavian artery
2. Axillary artery
3. Brachial artery
4. Radial artery
5. Ulnar artery

In this article, we will explore the anatomy of these arteries, their course, branches, and clinical correlations.

1. Subclavian Artery

Anatomical Course:

• Right side: Originates from the brachiocephalic trunk.
• Left side: Branches directly from the arch of the aorta.
• Travels laterally towards the axilla and is divided into three parts based on its relation to the anterior scalene muscle:
  1. First part: From the origin to the medial border of the anterior scalene.
  2. Second part: Posterior to the anterior scalene.
  3. Third part: From the lateral border of the anterior scalene to the first rib.
• At the first rib, the subclavian artery becomes the axillary artery.

2. Axillary Artery

Anatomical Course:

The axillary artery travels deep to the pectoralis minor muscle and is enclosed in the axillary sheath.

It is divided into three parts based on its relation to the pectoralis minor muscle:

1. First part: Proximal to pectoralis minor.
2. Second part: Posterior to pectoralis minor.
3. Third part: Distal to pectoralis minor.

Branches:

• The circumflex arteries form an anastomotic network around the surgical neck of the humerus and can be damaged in fractures.
• At the lower border of the teres major, the axillary artery becomes the brachial artery.

Clinical Relevance:

• Axillary Artery Aneurysm: A rare condition that can cause vascular compromise. It may compress the brachial plexus, leading to neurological symptoms such as paraesthesia and muscle weakness. Treatment involves surgical excision and grafting.

3. Brachial Artery

Anatomical Course:

• The brachial artery is a continuation of the axillary artery beyond the teres major muscle.
• It supplies the arm and branches into the profunda brachii (deep artery) shortly after the teres major, which supplies the posterior upper arm (e.g., triceps brachii).
• The brachial artery bifurcates into the radial and ulnar arteries at the cubital fossa.

Clinical Relevance:

• Occlusion or Laceration: A complete occlusion can result in ischaemia, causing muscle necrosis. This may lead to Volkmann’s ischaemic contracture, a flexion deformity due to muscle fibrosis.

4. Radial and Ulnar Arteries

Anatomical Course:

• The radial artery supplies the posterolateral forearm and can be palpated at the wrist, lateral to the tendon of the flexor carpi radialis.
• The ulnar artery supplies the anteromedial forearm and contributes to the anastomotic network around the elbow joint.

Key Points:

• Radial artery: Contributes to the elbow and wrist anastomoses and supplies the hand.
• Ulnar artery: Gives rise to the anterior and posterior interosseous arteries.

5. Superficial and Deep Palmar Arches

Anatomical Course:

• The ulnar artery enters the hand and forms the superficial palmar arch.
• The radial artery contributes to the deep palmar arch.
• The superficial and deep palmar arches supply blood to the fingers and wrist joints.

Clinical Relevance:

• Anastomotic networks between these arches ensure continued perfusion of the hand even under pressure.

Points to Remember:

1. The subclavian artery becomes the axillary artery at the first rib.
2. The axillary artery is divided into three parts by the pectoralis minor muscle.
3. The brachial artery gives rise to the profunda brachii and terminates by bifurcating into the radial and ulnar arteries.
4. Radial and ulnar arteries supply the forearm and hand, forming arterial arches in the hand.
5. Proper understanding of these arteries is crucial for diagnosing and treating vascular injuries or conditions like aneurysms and occlusions.