Chapter 7: Vessels, lymphatic drainage and the breast
The blood from the upper limb is returned to the heart by two sets of veins, superficial and deep. Both sets have valves, and both drain ultimately into the axillary vein.
Superficial Veins (fig. 7-1). The superficial veins are highly variable, lie mostly in the subcutaneous tissue, and return almost all of the blood. Digital veins drain into a dorsal venous network in the hand, which leads to two prominent veins, the cephalic and the basilic.
The cephalic vein begins immediately posterior to the styloid process of the radius, where it can be cut down on in an emergency. It then winds anteriorly around the lateral border of the forearm, reaches the cubital fossa anterior to the elbow, ascends lateral to the biceps, lies in the groove between the deltoid and pectoralis major muscles (where it can be exposed surgically), and drains into the axillary vein.
The basilic vein winds anteriorly around the medial border of the forearm toward the medial epicondyle, ascends medial to the biceps, pierces the fascia, and accompanies the brachial artery to the axilla, where it joins the brachial veins and becomes the axillary vein.
In the cubital fossa, the cephalic and basilic veins are frequently connected by the median cubital vein, which runs superomedially from the cephalic to the basilic. It may receive a vessel (median antebrachial vein) from the anterior forearm. The median cubital crosses the bicipital aponeurosis, which separates it from the underlying brachial artery and median nerve. The median cubital vein or an associated vessel is used for taking blood samples (plebotomy), for intravenous injections, for blood transfusions, and for the introduction of catheters.
The valves in the superficial veins of the forearm allow flow only in a proximal direction (demonstrated by Harvey in 1628).
Deep veins. The deep veins accompany the arteries, usually in cross-connected pairs (venae comitantes), contain valves, and ultimately reach the axillary vein, which continues as the subclavian vein.
The lymphatic vessels of the upper limb, most of those from the breast, and the cutaneous vessels of the trunk above the level of the umbilicus drain into the axillary nodes.
Lymphatics from the fingers accompany the cephalic and basilic veins and enter the lateral axillary and deltopectoral (or infraclavicular) nodes (fig. 7-2).
Axillary Nodes. These important nodes are arbitrarily divided into five groups (fig. 7-2).
1. The lateral nodes lie behind the axillary vein and drain the upper limb.
2. The pectoral nodes, at the inferior border of the pectoralis minor, drain most of the breast.
3. The posterior, or subscapular, nodes, in the posterior axillary fold, drain the posterior shoulder.
4. The central nodes, near the base of the axilla, receive the lymph from the preceding three groups. They form the group most likely to be palpable (against the lateral thoracic wall).
5. The apical nodes lie medial to the axillary vein and superior to the pectoralis minor. The apical nodes receive the lymph from all the other groups and sometimes directly from the breast. They drain into two or three subclavian trunks, which enter the jugular-subclavian venous confluence, or join a common lymphatic duct, or empty into lower, deep cervical nodes.
The breast overlies the pectoralis major, serratus anterior, and external oblique muscles. It usually extends from the second to the sixth ribs but the mammary gland is more extensive than the breast and generally extends into the axilla as an "axillary tail." The upper, outer quadrant of the breast contains a large amount of glandular tissue and is the site of 60 per cent of carcinomas of the breast.
The mammary gland is situated within the subcutaneous tissue, deep to which is the fascia covering the pectoralis major and serratus anterior. The gland is normally mobile on the fascia. The parenchyma is arranged in about 15 to 20 lobes, each of which is drained by a lactiferous duct opening on the nipple. The ducts, each of which may show a sinus near its termination, can be injected with a radioopaque medium and then visualized radiographically (galactogram). The stroma, which consists of adipose and fibrous tissue, is inseparably intermingled with the epithelial parenchyma. On the anterior side, the subcutaneous tissue sends, in the words of Sir Astley Cooper, "large, strong, and numerous fibrous processes, to the posterior surface of the skin which covers the breast." These suspensory ligaments account for the dimpling of the skin seen in certain pathological conditions, such as carcinoma.
The nipple contains the minute openings of the lactiferous ducts. It contains smooth muscle, which compresses the ducts and renders the nipple erect. The nipple is surrounded by an areola of pigmented skin, which darkens during pregnancy and then remains so. The areola contains accessory mammary glands, sweat glands, and sebaceous glands that form tubercles during pregnancy and lubricate the nipple during lactation.
Two vertical ectodermal thickenings, the mammary ridges, appear on the trunk during embryonic life, and these extend from the axilla to the inguinal region. The rostral part of each forms the nipple. The mammary glands develop from the nipples during fetal life. Accessory nipples (polythelia) or glands (polymastia) usually, but not invariably, develop on the line of the mammary ridges. At puberty, in the female, the breasts grow and the ducts bud and form lobules, but true secretory alveoli do not develop until pregnancy. The glandular tissue involutes after the menopause.
The mammary gland is highly vascular and is supplied by branches of the internal thoracic, axillary, and intercostal arteries. Deep veins drain into the correspondingly named veins. Connections between the intercostal veins and the vertebral plexus allow metastasis to bones and to the nervous system.
The lymphatic and venous drainages of the breast are of great importance in the spread of carcinoma (fig. 7-2). About three quarters of the lymphatic drainage is to the axillary nodes: (1) Lymphatics pass around the edge of the pectoralis major and reach the pectoral group of axillary nodes; (2) routes through or between the pectoral muscles may lead directly to the apical nodes of the axilla; (3) lymphatics follow the blood vessels through the pectoralis major and enter the parasternal (internal thoracic) nodes; (4) connections may lead across the median plane and hence to the contralateral breast; (5) lymphatics may reach the sheath of the rectus abdominis and the subperitoneal and subhepatic plexuses.
It should be noted that free communication exists between nodes below and above the clavicle and between the axillary and cervical nodes.
The main artery carrying blood to the upper limb is named successively subclavian, axillary, and brachial. In addition to its supply to the upper limb, it has branches supplying the pectoral and scapular regions, structures of the base of the neck and the vital structures of the brain stem. The arrangement of this vessel and its branches is summarized in figure 7-3. The subclavian artery arches superior to the first rib and changes its name to axillary artery at the lateral border of that rib. At the base of the axilla, where the axillary artery reaches the inferior border of the teres major, its name changes to brachial. Immediately distal to the elbow joint, the brachial artery divides into the radial and ulnar arteries, which, when they reach the hand, form anastomotic connections known as the superficial and deep palmar arches. A number of metacarpal and digital branches supply the fingers.
Harvey, W., Movement of the Heart and Blood in Animals, trans. by K. J. Franklin, Blackwell, Oxford, 1957 (distributed in the United States by Charles C Thomas, Springfield, Illinois). Harvey's classic demonstration of the venous valves in 1628 is in Chapter 13.
7-1 Where was the usual site for bloodletting?
7-2 When a cardiac catheter is inserted at the right elbow, how does it reach the heart?
7-3 What is the effect on the superficial veins of opening and closing the fist?
7-4 In which layer is the mammary gland situated?
7-5 What are the suspensory ligaments of the breast?
7-6 What is the "axillary tail?"
7-7 Into which nodes do most of the lymphatics of the breast drain?
7-8 Does the lymphatic drainage of the breast involve the pectoral muscles?
Figure 7-1 Diagram of some common patterns of the superficial veins of the upper limb. Only the larger channels at the elbow are shown: these are the ones most likely to be visible through the skin.
Figure 7-2 Diagram of the lymphatic drainage of the upper limb and breast. The supratrochlear and deltopectoral nodes receive many superficial lymphatic vessels. The axillary nodes are indicated by capital letters. The lateral nodes drain the upper limb. The subareolar plexus drains by collecting trunks into the axillary nodes. The pectoral nodes drain most of the breast. The apical nodes receive the lymph from the other axillary groups. Retropectoral (R) and transpectoral (n routes are also shown.
Figure 7-3 The arteries of the upper limb. The sagittal section (lower right) is based on Grant.