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Axillary region

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Arteries, veins and nerves of the shoulder and arm.

The axillary region is the area between the superior portion of the upper limb and the thorax. Bordered by the serratus anterior and the thoracic wall medially, a part of the humerus laterally, the pectoralis muscles anteriorly, together with the latissimus dorsi, but not only, posteriorly, the axilla is an important region, both in terms of neurovasculature and clinical relevance. 

The axilla allows the passage of several muscles, blood vessels such as the axillary artery and vein, and crucial nerves like the brachial plexus. In this article, we will explore all of the contents more deeply, and we will examine the anatomy and relevant clinical conditions of the axillary region.

Key facts about the axilla
Borders Medially - serratus anterior, thoracic wall
Laterally - intertubercular sulcus of the humerus
Anteriorly - pectoralis major and minor
Posteriorly - subscapularis, latissimus dorsi, teres major muscles
Contents Muscles - coracobrachialis, pectoralis minor, and the biceps brachii
Blood vessels - axillary artery and vein
Nerves - brachial plexus
Lymphatics - axillary lymph nodes (pectoral, subscapular, lateral, central, infraclavicular groups)
  1. Anatomical borders
  2. Contents
    1. Axillary artery
    2. Axillary vein
    3. Brachial plexus
    4. Axillary lymph nodes
  3. Clinical points
    1. Radial nerve palsy
    2. Winged scapula
    3. Breast cancer
    4. Chest tube (drain) insertion
  4. Sources
+ Show all

Anatomical borders

Axillary region in a cadaver. Notice how the axilla looks like a pyramidal gap between the lateral thoracic wall and the upper limb.

The axilla is a three dimensional pyramidal space which changes shape due to its location and arm movement.

  • Its apex is bound superiorly by the root of the neck. The apex is also referred to as the axillary inlet. The borders of the apex are made by the lateral surface of the first rib, the posterior surface of the clavicle, and the superior margin of the scapula.
  • The medial border is created by the serratus anterior, as well as the thoracic wall which includes intercostal muscles and costals (ribs) of that region.
  • The lateral border is made by the intertubercular sulcus (groove) of the humerus.
  • The floor, or base, of the axilla is the axillary fascia and its skin on the surface of the axilla, aka the ‘armpit’. The axilla is filled with adipose (fat) and allows passage for: vessels, nerve plexus, lymphatics, and muscles. The muscles include the coracobrachialis, pectoralis minor, and the biceps brachii.
  • The posterior border of pectoralis major and minor defines the anterior border (fold).
  • The posterior border (fold) is the subscapularis superiorly, and the latissimus dorsi and teres major inferiorly. The intercostobrachial nerves supply sensation to the skin of the axilla.

Wondering how to learn anatomy faster and more efficiently? Try out our free anatomy quizzes and guides!


The axilla contains both the axillary artery and axillary vein. The vein runs medial to the artery along its length. The cords of the brachial plexus surround the axillary artery and are named after their position relative to the artery.

Axillary artery

The subclavian artery is renamed the axillary artery once it passes the lateral border of the first rib. The axillary artery supplies the upper limb and is divided into three parts: the region proximal to pectoralis minor, the region beneath it, and the region distal to it.

First section

The first section gives rise to the superior thoracic artery, which supplies the first and second intercostal spaces.

Second section

The second part gives rise to the lateral thoracic artery and the thoracoacromial artery ,which has a pectoral branch, acromial branch, clavicular branch, and deltoid branch. The pectoral branch supplies the pectoral muscles and anastomoses with the internal and lateral thoracic arteries. The acromial branch supplies the deltoid and also anastomoses with arteries around the shoulder (thoracoacromial, subscapular, and posterior humeral circumflex arteries). The clavicular branch supplies subclavius, and the sternoclavicular joint. The deltoid branch runs in the deltopectoral groove and supplies the deltoid and pectoralis major muscles.

Third section

The third section gives rise to the subscapular artery, the anterior circumflex humeral artery, and the posterior circumflex humeral artery. The subscapular artery supplies the supraspinatus and the infraspinatus muscles. The anterior and posterior circumflex humeral arteries supply the muscles near the surgical neck of the humerus.

Do you find it difficult to memorize the branches of the axillary artery? Grinding and aimlessly re-reading doesn't help, but the following mnemonic does!

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  • Superior thoracic artery
  • Thoracoacromial artery
  • Lateral thoracic artery
  • Anterior circumflex humeral artery
  • Posterior circumflex humeral artery
  • Subscapular artery

Axillary vein

The axillary vein drains the upper limb and is formed by the unification of the basilic and brachial veins. The cephalic vein joins at the proximal region of the vein. It is renamed the subclavian vein once it passes the lateral border of the first rib.

Brachial plexus

Medial cord

The brachial plexus arises from the anterior rami of spinal nerves C5 to T1. The medial cord gives rise to the ulnar nerve (C8-T1). This nerve is the main nerve that innervates the intrinsic hand muscles, apart from the thenar eminence and radial two lumbricals. Flexor carpi ulnaris and the ulnar head of flexor digitorum profundus are also innervated by the ulnar nerve. The ulnar nerve also supplies sensation to the palmar and dorsal surfaces of the ulnar one and a half fingers.

Posterior cord

The posterior cord gives rise to the radial nerve (C5-T1), which innervates the triceps brachii and the extensor muscles of the forearm. It also supplies sensation over the posterior surface of the arm, forearm, and hand. The axillary nerve (C5-6) is also a branch of the posterior cord, and innervates the deltoid and teres minor muscles. It also supplies sensation over the regimental patch area of the shoulder. The thoracodorsal nerve (C6-8) is also a branch of the posterior cord and innervates the latissimus dorsi.

Lateral cord

The lateral cord gives rise to the musculocutaneous nerve (C5-6/7), which innervates the flexor compartment of the arm: biceps brachii, brachialis, and coracobrachialis. It also is renamed the lateral cutaneous nerve of the forearm (antebrachial) after it leaves the flexor compartment of the arm.

The median nerve (C6-T1) is formed by the unification of branches from the medial and lateral cords. It innervates all the muscles of the flexor compartment of the forearm, aside from flexor carpi ulnaris and the ulnar head of flexor digitorum profundus. In the hand, the medial nerve supplies the thenar eminence and radial two lumbricals. It also supplies sensation over the palmar aspect of the radial 3 ½ fingers, as well as the nailbeds of these fingers dorsally.

Compression of these cords, or nerves in the axillary region, can result in muscle wasting, fasciculations, and weakness. Loss of sensation may also result. The axillary region is therefore an important clinical region, simple due to the multitude of structures that pass through the region.

The long thoracic nerve arises from the C5-7 nerve roots and innervates the serratus anterior. An easy way to remember this is by using the mnemonic 'C5, 6, 7 raise your arms to heaven!'. This nerve descends through the axillary region. The intercostobrachial nerves are the sensory (cutaneous) branches of the intercostal nerves. They descend in the axilla and supplies the posterior and medial surface of the arm.

Learn everything about the brachial plexus with our articles, video tutorials, quizzes, and labelled diagrams:

Axillary lymph nodes

The axillary lymph nodes are divided into five groups.

Anterior group

The anterior group (pectoral group) drains the lymph from the anterolateral aspect of the abdominal wall, superior to the level of the umbilicus and the lateral quadrants of the breast.

Posterior group

The posterior group (subscapular group) drain the superficial lymphatic vessels from the back, as far back as the superior border of the iliac crests.

Lateral group

The lateral group drains the majority of lymphatic fluid from its upper limb.

Central nodes

The central nodes receive lymph flow from the anterior, posterior, and lateral group of lymph nodes. These all drain into the apical nodes (subclavicular group), which are located at the lateral border of the first rib at the apex of the axilla. The lymph then flows to the subclavian lymph trunk. The drainage is different on the left and right sides. The left side axillary drainage flows into the thoracic duct. Whereas on the right side the drainage is into the right lymphatic trunk.

Deltoid group

The infraclavicular (deltoid group) of lymph nodes do not strictly reside within the axilla, however, they lie in the deltopectoral groove and drain the superficial lymphatic vessels of its associated upper limb (arm, forearm, and hand).

Feeling ready to consolidate your knowledge on the neurovascular contents of the axillary region? Try out this quiz below:

Axillary region: want to learn more about it?

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