Overview of Upper Limb - LO 4

4. Describe the primary arterial supply of the upper limb.

The axillary artery is the primary blood supply to the upper limb.

As a continuation of the subclavian a. beyond the inferior margin of the 1st rib, the axillary a. courses through the axilla, giving off numerous branches to supply the shoulder muscles and joint. The axillary a. continues into the arm as the brachial a. at the inferior margin of teres major m.

The brachial a. supplies the anterior (flexor) compartment of the arm. Proximally, the brachial a. gives off the deep artery of the arm (deep brachial a.), that dives posterior to the humerus to supply the posterior (extensor) compartment of the arm.

The brachial a. continues through the anterior compartment into the cubital fossa (anterior to the elbow), where it divides into the radial a. and ulnar a. Note, that at the elbow (as is the case with most joints), there are several branches from several different arteries that supply the joint area – they form numerous anastomoses that provide significant collateral supply to the joint and surrounding tissue.

The radial a. supplies the radial side (lateral) of the forearm flexors as it courses through the anterior forearm. At its distal end (at the wrist) it courses onto the dorsum of the lateral hand to run between the tendons of the extrinsic thumb muscles – often referred to as the “anatomical snuff box”. Abduct and extend your own thumb to see the tendons and notice the space between the tendons at your wrist – anatomical snuff box. The radial artery courses through this space onto the dorsum of the hand between the thumb and index finger. It dives through the muscle there to supply the deep palmar region of the hand.

The ulnar a. supplies the ulnar side (medial) of the forearm flexors as it courses through the anterior forearm. It courses across the wrist (where there is a good pulse point) into the hand to primarily supply the superficial palmar region of the hand.  The ulnar and radial arteries anastomose (via deep and superficial palmar arches created by the radial and ulnar arteries) in the palmar region of the hand. Please refer to Session 20 for more detail.

At the proximal end of the ulnar artery, just distal to the cubital fossa area, the ulnar artery gives off the common interosseous a., that divides into anterior interosseous a. and posterior interosseous a. The anterior interosseous a. runs on the anterior surface of the interosseous membrane to supply the deep (flexor) compartment. The posterior interosseous a. runs on the posterior surface of the interosseous membrane to supply the posterior (extensor) compartment.

In fewer words [note these are generalizations; there are exceptions to these rules]...

• • Subclavian a. (to the lateral margin of 1st rib)

    • Axillary a. (to the inferior margin of teres major m.) → axilla

      • Brachial a. (to the cubital fossa) → anterior (flexor) compartment of the arm

        • Deep artery of the arm (deep brachial a.) → posterior (extensor) compartment of the arm

        • Radial a.  → lateral portions of the anterior (flexor) compartment of forearm

          • Deep palmar arterial arch → hand and digits

        • Ulnar a. →  medial portions of the anterior (flexor) compartment of forearm

          • Common interosseous a.

            • Anterior interosseous a. → deep layer of anterior (flexor) compartment of forearm

            • Posterior interosseous a. → posterior (extensor) compartment of forearm

          • Superficial palmar arterial arch → hand & digits