Axillary Artery: Anatomy, Branches & Relations

Axillary Artery

Definition: The main artery of the upper limb.

➜ Begins: Outer border of 1st Rib.
➜ Ends: Lower border of Teres Major.
➜ Course: Runs from apex to base. Lies nearer to the Anterior Wall than the posterior wall.

Course and branches of the axillary artery

Parts & Relations

Divided into 3 parts by Pectoralis Minor. The Axillary Vein is always medial.

1. First Part (Superior)

diagram showing the anterior, posterior, medial, and lateral relations of the first part of the axillary artery

Relations of Axillary Artery : first part

Anterior: Pectoralis Major (clavicular), Loop of communication (Lat/Med pectoral nerves).

Posterior: Medial cord of BP, Long thoracic nerve, Serratus Anterior (1st digitation).

Medial: Axillary Vein.

Lateral: Lateral & Posterior cords of BP.

2. Second Part (Posterior/Deep)

diagram showing the anterior, posterior, medial, and lateral relations of the second part of the axillary artery

Relations of Axillary Artery : second part

Anterior: Pectoralis Minor.

Posterior: Posterior cord of BP, Subscapularis.

Medial: Medial cord of BP, Axillary Vein.

Lateral: Lateral cord of BP.

3. Third Part (Inferior)

diagram showing the anterior, posterior, medial, and lateral relations of the third part of the axillary artery

Relations of Axillary Artery : third part

Anterior: Medial root of Median nerve.

Posterior: Radial n., Axillary n., Subscapularis (upper), Teres major (lower).

Medial: Axillary Vein, Medial cut. nerve of forearm, Ulnar nerve.

Lateral: Musculocutaneous nerve.

Branches

Mnemonic: S - T - L - S - A - P
(Save The Lions, Save All People)

A. From 1st Part (1)

1. Superior Thoracic A: Arises near subclavius. Supplies Pectoralis Major/Minor & Medial wall.

B. From 2nd Part (2)

1. Thoraco-acromial A: Pierces clavipectoral fascia. Branches radiate at Right Angles:

(a) Pectoral (b) Deltoid (c) Clavicular (supplies S-C joint) (d) Acromial

2. Lateral Thoracic A: Supplies Pectorals & Serratus Ant.
✱ Clinical: Large in females (lateral mammary branches to breast).

C. From 3rd Part (3)

1. Subscapular A: (Largest). Ends near inferior angle of scapula. Gives Circumflex Scapular A. (passes through Upper Triangular Space).

2. Ant. Circumflex Humeral A: Forms arterial circle around surgical neck. Ascending branch supplies head of humerus.

3. Post. Circumflex Humeral A: Passes through Quadrangular Space with Axillary Nerve. Supplies Deltoid & Shoulder Joint.

Scapular Anastomosis

Anastomosis around the scapula

Collateral path between Subclavian (1st part) & Axillary (3rd part).

➜ Body of Scapula: Suprascapular + Deep branch of Transverse Cervical + Circumflex Scapular.
➜ Acromion Process: Acromial branches of Thoraco-acromial, Suprascapular & Post. Circumflex Humeral.

Clinical Correlation

Collateral Circulation: If Axillary artery is blocked (e.g., between 1st and 3rd part), this anastomosis serves as a potential pathway to ensure adequate circulation to the upper limb.

📚 Ref: Vishram Singh - Upper Limb and Thorax

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