Brachial artery

Course

As a continuation of the axillary artery, it begins at the inferior border of the teres major tendon and it ends at the level of the neck of the radius about 1cm distal to the elbow joint. At this point, it divides into the ulnar and radial arteries. The brachial artery runs medial to the humerus proximally, before moving more anteriorly to lie between the epicondyles of the humerus.

Anatomical relations

Relationships of the brachial artery to other structures in the arm can be important in clinical practice. The brachial artery is a superficial vessel and is only covered by the layers of the skin, as well as the superficial and deep fasciae, with a few exceptions:

• The first exception to this is at the cubital fossa, where the bicipital aponeurosis, which is the aponeurosis of the biceps brachii muscle, covers the artery, and separates it from the median cubital vein.
• The second exception is when the median nerve crosses the brachial artery near the distal attachment of the coracobrachialis.

Posteriorly, the brachial artery is separated from the long head of the triceps brachii muscle by the deep brachial artery and the radial nerve. The attachments of the coracobrachialis and the brachialis muscles, as well as the medial head of the triceps brachii muscle, also lie posterior to the brachial artery.

The median nerve and coracobrachialis muscle lie laterally to the brachial artery at its proximal aspect whereas the medial cutaneous nerve of the forearm and the ulnar nerve lie medially to the artery proximally.

At the distal aspect of the brachial artery, the basilic vein and median nerve lie medially. Two venae comitantes, or accompanying veins, run with the brachial artery, and are connected together by transverse and oblique branches.

Do you want to learn the main arteries of the upper limb? Check out the following study unit:

Anatomical variations

Along with many other structures in the human body, the anatomical course of the brachial artery may vary between people:

• The brachial artery may diverge from its usual course along the medial aspect of the biceps and run more medially towards the medial epicondyle of the humerus. In this case, the brachial artery passes posterior to the supracondylar process of the humerus before running through, or posterior to, the pronator teres muscle.
• The brachial artery can also form anastomoses or branches more proximal than usual. In this case, the artery divides into three branches referred to as the ulnar, radial and common interosseous arteries. The radial artery usually arises from the brachial artery more proximally, leaving a common division for the ulnar and common interosseus arteries. Occasionally, the ulnar artery may instead branch off more proximally, which then leaves a common division for the radial and common interosseous arteries.
• Sometimes, small slender arteries connect the brachial artery to the axillary artery and these are referred to as vasa aberrantia.

Branches

The brachial artery forms 5 consistent branches including the:

• Deep brachial artery
• Superior ulnar collateral artery
• Inferior ulnar collateral (supratrochlear) artery
• Radial artery
• Ulnar artery

The deep brachial artery is a large posteromedial branch of the brachial artery, distal to the teres major muscle. It accompanies the radial nerve in its course. It runs initially posteriorly between the medial and long heads of the triceps brachii muscle before continuing within the spiral groove of the humerus. It then divides into two branches, the middle collateral (posterior descending) branch and the radial collateral (anterior descending) branch.

Wondering how you can test yourself on the different branches of the brachial artery? Try flashcards! Here's how you can make your own.

The superior ulnar collateral artery arises from the brachial artery slightly distal to the mid-level of the arm but can occasionally arise as a branch of the deep brachial artery. Along the ulnar nerve, it passes through the medial intermuscular septum into the posterior compartment of the arm to supply the medial head of the triceps brachii muscle. It then runs between the medial epicondyle of the humerus and the ulnar epicondyle. Deep to the flexor carpi ulnaris muscle, it joins the inferior collateral artery and the posterior branch of the posterior ulnar recurrent artery. Sometimes, a branch anastomoses with the anterior ulnar recurrent artery after it travels anteriorly to the medial epicondyle.

The inferior ulnar collateral (supratrochlear) artery arises from the brachial artery about 5cm proximal to the elbow joint. It runs medially between the brachialis muscle and the median nerve before crossing the medial intermuscular septum. It then spirals round the humerus between the bone and the triceps brachii muscle until it anastomoses with the middle collateral branch of the deep brachial artery to form an arch located proximally to the olecranon fossa, a depression on the posterior aspect of the humerus. Anterior to the brachialis muscle, the inferior ulnar collateral artery divides into a few branches, which either run anteriorly to the medial epicondyle to anastomose with the anterior ulnar recurrent artery or run posteriorly to it to anastomose with the posterior ulnar recurrent artery and superior ulnar collateral artery.

The radial artery runs deep to the brachioradialis to give off the radial recurrent artery distal to the elbow joint. It runs between the superficial and deep branches of the radial nerve before it passes, in a superior direction, posteriorly to the brachioradialis muscle and anteriorly to the supinator and brachialis muscles. It supplies the brachioradialis, supinator and brachialis muscles as well as the elbow joint, before anastomosing with the radial collateral branch of the deep brachial artery.

The ulnar artery is the largest of the terminal branches of the brachial artery. Its earliest branch is the ulnar recurrent artery, which subsequently divides into its anterior and posterior branches. Proceeding down the forearm, the ulnar artery gives off the common interosseous artery, dorsal, palmar and deep carpal branches, as well as the superficial palmar arch; all of which contribute to the blood supply of the forearm and hand together with the branches of the radial artery

Mnemonics

Here's an easy way to remember the main branches of the brachial artery.

"Dogs Sprint In Rainy Underpasses"

• Deep brachial artery
• Superior ulnar collateral artery
• Inferior ulnar collateral artery 
• Radial artery 
• Ulnar artery 

To easily remember the anastomosis of the ulnar collateral and recurrent branches use the following mnemonic.

I Am Pretty Smart

• Inferior ulnar collateral artery goes with Anterior branch of ulnar recurrent artery
• Posterior branch of ulnar recurrent artery goes with Superior ulnar collateral artery

Before you finish up, take a quiz on the brachial artery and its branches to solidify your knowledge.