BLOOD SUPPLY OF THE UPPER ARM
The subcutaneous veins of the limb are interconnected with the deep veins of the limb via perforating veins.
Certain prominent veins, unaccompanied by arteries, are found in the subcutaneous tissues of the limbs. The cephalic and basilic veins, the principal superficial veins of the upper limb, originate in venous radicals in the hand and digits.
Anastomosing longitudinal palmar digital veins empty at the webs of the fingers into longitudinally oriented dorsal digital veins. The dorsal veins of adjacent digits then unite to form relatively short dorsal metacarpal veins, which end in the dorsal venous arch. The radial continuation of the dorsal venous arch is the cephalic vein, which receives the dorsal veins of the thumb and then ascends at the radial border of the wrist. In the forearm, it tends to ascend at the anterior border of the brachioradialis muscle, with tributaries from the dorsum of the forearm. In the cubital space, the obliquely ascending median cubital vein connects the cephalic and basilic veins (see Plate 2-12). Above the cubital fossa, the cephalic vein runs in the lateral bicipital groove and then in the interval between the deltoid and pectoralis major muscles, where it is accompanied by the small deltoid branch of the thoracoacromial artery. At the deltopectoral triangle, the cephalic vein perforates the costocoracoid membrane and empties into the axillary vein. An accessory cephalic vein passes from the dorsum of the forearm spirally laterally to join the cephalic vein at the elbow.
The basilic vein continues to the ulnar end of the venous arch of the dorsum of the hand. It ascends along the ulnar border of the forearm and enters the cubital fossa anterior to the medial epicondyle of the humerus. After receiving the median cubital vein, the basilic vein continues upward in the medial bicipital groove, pierces the brachial fascia a little below the middle of the arm, and enters the neurovascular compartment of the medial intermuscular septum, where it lies superficial to the brachial artery. In the distal axilla, it joins the brachial veins to form the axillary vein.
The median antebrachial vein is a frequent collecting vessel of the middle of the anterior surface of the forearm (see Plate 2-12). It terminates in the cubital fossa in the median cubital vein or in the basilic vein. It sometimes divides into a median basilic vein and a median cephalic vein, which borders the biceps brachii laterally and joins the cephalic vein. The median antebrachial vein may be large or absent.
The brachial artery, the continuation of the axillary artery, extends from the lower border of the teres major muscle to its bifurcation opposite the neck of the radius in the lower part of the cubital fossa. The course of the vessel may be marked with the limb in right-angled abduction, when the vessel lies on a line connecting the middle of the clavicle with the midpoint between the epicondyles of the humerus. The brachial artery lies deep in the neurovascular compartment of the arm, flanked by the brachial veins on either side and by the median nerve anterior to it. The median nerve gradually crosses the artery to lie medial to it in the cubital fossa. These structures are crossed by the bicipital aponeurosis at the elbow.
The brachial artery is a single vessel in 80% of cases. In the other 20% of cases, a superficial brachial artery arises at the level of the upper arm and descends through the arm anterior to the median nerve. Based on its forearm distribution, this artery is a high radial artery in 10% of cases, is a high ulnar artery in 3%, and forms both radial and ulnar arteries in 7%. In the last case, the brachial artery is likely to become the common interosseous artery of the forearm.
The brachial artery provides numerous muscular branches in the arm, principally from its lateral side. An especially large branch supplies the biceps brachii muscle. The branches are named as follows:
1. The deep brachial artery arises from the medial and posterior aspect of the brachial artery, below the tendon of the teres major muscle. It is the largest branch of the brachial artery and accompanies the radial nerve in its diagonal course around the humerus. At the back of the humerus, the artery provides an ascending (deltoid) branch, which reaches up to anastomose with the descending branch of the posterior circumflex humeral artery. The deep brachial artery then divides into the middle collateral artery and the radial collateral arteries. The middle collateral artery plunges into the medial head of the triceps brachii muscle and descends to the anastomosis of vessels at the level of the elbow. The radial collateral artery continues with the radial nerve, both perforating the lateral intermuscular septum to enter the anterior compartment. The artery ends in the elbow joint anastomosis, connecting in particular with the radial recurrent artery from the radial artery. All these branches nourish the muscles of the arm to which they are adjacent.
2. The nutrient humeral artery arises about the middle of the arm and enters the nutrient canal on the anteromedial surface of the humerus.
3. The superior ulnar collateral artery arises from the brachial artery at or a little below the middle of the arm. It pierces the medial intermuscular septum, descending behind it with the ulnar nerve. With the nerve, it passes behind the medial epicondyle of the humerus to anastomose with the inferior ulnar collateral artery and the posterior ulnar recurrent branch of the ulnar artery.
4. The inferior ulnar collateral artery arises from the brachial artery about 3 cm above the medial epicondyle. It divides on the brachialis muscle into anterior and posterior branches. Both these branches reach the anastomosis around the elbow joint, anterior and posterior to it, respectively.
Brachial veins accompany the artery, one on either side of it. They are formed from the venae comitantes of the radial and ulnar arteries and have tributaries that accompany the branches of the brachial artery, draining the areas supplied by the arteries. The brachial veins contain valves and frequently anastomose with one another. At the lower border of the teres major muscle, the lateral of the two veins crosses the artery to join the more medial one; then, joined by the basilic vein, they form the axillary vein.
Blood Supply To The Elbow
The blood supply of the elbow joint comes from the anastomosis of the collateral branches of the brachial artery and the recurrent branches of the radial and ulnar arteries.
Like the axilla, the cubital fossa is a space at the bend of the elbow where it is helpful to note the important relationships of structures that overlie the elbow joint. It is described as a triangular space, apex downward, and is bound above by a line connecting the epicondyles of the humerus. The converging side borders are muscular, the pronator teres muscle medially and the brachioradialis muscle laterally. The floor of the space is also muscular, consisting of the brachialis muscle of the arm and the supinator muscle of the forearm; deep to these muscles is the elbow joint.
The readily palpable tendon of the biceps brachii muscle descends centrally through the space, and its bicipital aponeurosis spans medialward across the brachial artery and median nerve to blend with the forearm fascia over the flexor muscle mass. Directly medial to the biceps brachii tendon, the brachial artery divides into the radial and ulnar arteries in the inferior part of the cubital fossa opposite the neck of the radius.
Although submerged between the brachioradialis and brachialis muscles, the radial nerve can be exposed by drawing the brachioradialis muscle lateralward and can be followed to its bifurcation into deep and superficial branches. Superficially, the medial cubital vein crosses obliquely, overlying the bicipital aponeurosis; and a medial cephalic vein may, on occasion, lie subcutaneously toward the lateral side of the fossa. The medial antebrachial cutaneous nerve crosses the median cubital vein, and the lateral antebrachial cutaneous nerve passes deep to the median cephalic vein, if it is present.