4 Neurovascular Systems: Forms and Relations
4.1 The Arteries
A Course of the different segments of the arteries supplying the shoulder and arm
Subclavian artery: The right subclavian artery arises from the brachiocephalic trunk (as shown here), and the left arises directly from the aortic arch. The vessel runs over the first rib between the anterior and middle scalene (interscalene space, scalene interval) and continues as the axillary artery (see below) on reaching the lateral border of the rib. Unlike the other arteries pictured here, the subclavian artery supplies blood not only to the upper limb (i. e., the shoulder girdle and arm) but also to
• a portion of the neck,
• the cerebral circulation, and
• the anterior chest wall.
Axillary artery: The continuation of the subclavian, the axillary artery runs from the lateral border of the first rib to the inferior border of the teres major muscle.
Brachial artery: The brachial artery is the continuation of the axillary artery. It ends at the elbow joint by dividing into the radial and ulnar arteries.
Radial artery: The radial artery runs distally on the radial side of the forearm from the division of the brachial artery, passing between the brachioradialis and flexor carpi radialis muscles on its way to the wrist. It terminates in the deep palmar arch.
Ulnar artery: This second division of the brachial artery runs below the pronator teres on the ulnar side of the forearm, under cover of the flexor carpi ulnaris, to the superficial palmar arch.
B Overview of the arteries of the shoulder and arm
The arteries of the shoulder and arm vary considerably in their origins and branching patterns (the principal variants are reviewed in Chapter 5, Neurovascular Systems: Topographical Anatomy). The branches are listed below in the order in which they arise from the parent vessels.
Branches of the subclavian artery
• Vertebral artery
• Internal thoracic artery (internal mammary artery)
• Thyrocervical trunk
– Inferior thyroid artery
– Ascending cervical artery
– Suprascapular artery
– Transverse cervical artery
• Costocervical trunk
– Deep cervical artery
– Supreme intercostal artery
Branches of the axillary artery
• Superior thoracic artery
• Thoracoacromial artery
– Acromial branch
– Clavicular branch
– Deltoid branch
– Pectoral branch
• Lateral thoracic artery
• Subscapular artery
– Thoracodorsal artery
– Circumflex scapular artery
• Anterior circumflex humeral artery
• Posterior circumflex humeral artery
Branches of the brachial artery
• Deep artery of the arm (deep brachial artery)
– Medial collateral artery
– Radial collateral artery
• Superior ulnar collateral artery (arterial network of the elbow)
• Inferior ulnar collateral artery (arterial network of the elbow)
Branches of the radial artery
• Radial recurrent artery (arterial network of the elbow)
• Palmar carpal branch (palmar carpal network)
• Superficial palmar branch (superficial palmar arch)
• Dorsal carpal branch (dorsal carpal network)
– Dorsal metacarpal arteries
– Dorsal digital arteries
• Princeps pollicis artery
• Radialis indicis artery
• Deep palmar arch
– Palmar metacarpal arteries
– Perforating branches
Branches of the ulnar artery
• Ulnar recurrent artery (arterial network of the elbow)
• Common interosseous artery
– Posterior interosseous artery
– Recurrent interosseous artery
– Anterior interosseous artery
• Palmar carpal branch (palmar carpal network)
• Dorsal carpal branch (dorsal carpal network)
• Deep palmar branch (deep palmar arch)
• Superficial palmar arch
– Common palmar digital arteries
– Proper palmar digital arteries
C Arteries of the right upper limb
Anterior view with the forearm supinated. For clarity, some of the arteries listed in B are not illustrated.
D Arteries of the right hand
E Main arterial branches in the right forearm (perforating branches)
a From the radial artery and ulnar artery (forearm supinated, anterior view).
b From the posterior interosseous artery (forearm pronated, posterior view).
Fasciocutaneous flaps with an excellent vascular pedicle can be harvested from the thin skin of the forearm. Composed of skin, subcutaneous tissue, and fascia, these flaps are supplied by branches of the major arteries and their accompanying veins. The skin flaps carry this vascular supply with them when they are transferred to the recipient site.
4.2 The Veins
A Cutaneous veins and cutaneous nerves of the right elbow
Anterior view. The subcutaneous veins of the elbow are excellent sites for administering intravenous injections and drawing blood owing to their size and accessibility and the relatively thin skin in that region. But given their close relationship to the cutaneous nerves, as illustrated by the proximity of the basilic vein to the medial antebrachial cutaneous nerve, injections into these veins may cause severe transient pain, as in cases where an accidental “paravascular” injection irritates the surrounding connective tissue. “Rolling veins” refers to a condition in which the subcutaneous veins are exceptionally mobile within the subcutaneous fat. In approximately 3% of cases the ulnar artery may pass over the surface of the flexor muscles (superficial ulnar artery, see also p. 397). An unintended intra-arterial injection can have devastating consequences with certain medications. This complication can be avoided by palpating the vessel and confirming arterial-type pulsations before giving the injection and always drawing a small amount of blood back into the syringe (dark red = venous blood, bright red = arterial blood) before depressing the plunger.
B Cubital fossa of the right arm: variable course of the subcutaneous veins
a M-shaped venous pattern above the median antebrachial vein.
b Presence of an accessory cephalic vein from the venous plexuses on the extensor side of the forearm.
c Absence of the median cubital vein.
All of the illustrated variants are common.
D Superficial veins of the right upper limb
Anterior view. The main longitudinal trunks of the subcutaneous venous network of the arm are the median antebrachial vein, the basilic vein, and the cephalic vein.
Median antebrachial vein: This vein, unlike the cephalic and basilic, receives blood mainly from the cutaneous veins on the dorsum of the hand, draining the flexor side of the forearm. The variable median antebrachial vein opens into the corresponding longitudinal veins at the elbow, usually by way of the median cephalic vein and median basilic vein (see p. 379).
Basilic vein: This vein begins at the elbow, first ascending in the epifascial plane in the medial bicipital groove to the basilic hiatus, where it pierces the fascia in the middle of the arm. It terminates in a subfascial plane at the ulnar brachial vein.
Cephalic vein: In the arm the cephalic vein first ascends on the lateral side of the biceps brachii, then enters a groove between the deltoid and pectoralis major muscles (the deltopectoral groove). It finally opens into the axillary vein in the clavipectoral triangle (see p. 380).
E Superficial veins of the dorsum of the right hand
F Overview of the main superficial and deep veins of the upper limb
Numerous connections exist between the deep and superficial veins of the arm—the perforator veins. Valves are incorporated into the veins at regular intervals, increasing the efficiency of venous return (see p. 65).
Deep veins of the upper limb
• Subclavian vein
• Axillary vein
• Brachial veins
• Ulnar veins
• Radial veins
• Anterior interosseous veins
• Posterior interosseous veins
• Deep palmar venous arch
• Palmar metacarpal veins
Superficial veins of the upper limb
• Cephalic vein
• Accessory cephalic vein
• Basilic vein
• Median cubital vein
• Median antebrachial vein
• Median cephalic vein
• Median basilic vein
• Dorsal venous network of the hand
• Superficial palmar venous arch
4.3 The Lymphatic Vessels and Lymph Nodes
A Lymph vessels of the upper limb (after Schmidt and Lanz)
a Posterior view, b anterior view. The lymph vessels (lymphatics) in the upper limb are of two types:
• Superficial (epifascial) lymphatics
• Deep lymphatics
While the deep lymphatics of the upper limb accompany the arteries and deep veins, the superficial lymphatics lie in the subcutaneous tissue. In the forearm, they are most closely related to the cephalic and basilic veins. Numerous anastomoses exist between the deep and superficial systems. The arrows in the diagrams indicate the main directions of lymphatic drainage. Inflammations and infections of the hand generally incite a painful swelling of the axillary lymph nodes. When the lymph vessels are also involved, they are visible as red streaks beneath the skin (lymphangitis).
B Lymphatic drainage of the thumb, index finger, and dorsum of the hand (after Schmidt and Lanz)
The thumb, index finger, and part of the middle finger are drained by a radial group of lymph vessels that pass directly to the axillary lymph nodes. The other fingers are drained by an ulnar group of lymphatics (not shown here) that end at the cubital lymph nodes.
C Regional lymph nodes of the right upper limb
Anterior view. The lymph nodes of the axilla (axillary lymph nodes) are important collecting stations for the arm, shoulder girdle, and anterior chest wall. The 30 to 60 lymph nodes of the axilla are divided into several groups or levels, numbered I to III (see E), which are interconnected by lymph vessels. Taken together, the lymphatics in this region form an axillary lymphatic plexus lying within the fatty tissue. Lymphatic drainage from the axilla is collected in the subclavian trunk (not shown here). On the right side, the lymph is conveyed by the right jugular trunk and right bronchomediastinal trunk to the right lymphatic duct, which opens into the junction of the right subclavian and internal jugular veins (see p. 196).
D The axillary lymph nodes, grouped by levels
(after Henne-Bruns, Dürig, and Kremer)
Level I: lower axillary group
(lateral to pectoralis minor)
• Pectoral axillary lymph nodes
• Subscapular axillary lymph nodes
• Humeral axillary lymph nodes
• Paramammary lymph nodes
Level II: middle axillary group
(along the pectoralis minor)
• Interpectoral axillary lymph nodes
• Central axillary lymph nodes
Level III: upper, infraclavicular group
(medial to pectoralis minor)
• Apical axillary lymph nodes
E Classification of axillary lymph nodes by level
The axillary lymph nodes have major clinical importance in breast cancer. A malignant breast tumor will metastasize (seed tumor cells) to the axillary nodes as it grows. As a guide for surgical removal, the axillary lymph nodes can be segregated into groups arranged in three levels, based on their relationship to the pectoralis minor muscle (see p. 211).
• Level I: all the lymph nodes lateral to the pectoralis minor.
• Level II: all the lymph nodes along the pectoralis minor.
• Level III: all the lymph nodes medial to the pectoralis minor (see p. 302).
4.4 The Brachial Plexus: Structure
A Schematic representation of the structure of the brachial plexus
a Names and sequence of the various components of the brachial plexus.
b Relationship of the lateral, medial, and posterior cords of the brachial plexus to the axillary artery.
c Subdivision of the brachial plexus cords into their main branches.
B Number and location of the main components of the brachial plexus
1. Plexus roots (anterior rami of the spinal nerves from cord segments C5–T1)
Between anterior and middle scalene (interscalene space)
2. The primary trunks: upper, middle, and lower
Lateral to the interscalene space and above the clavicle
3. The three anterior and three posterior divisions
Posterior to the clavicle
4. The lateral, medial, and posterior cords
In the axilla, posterior to the pectoralis minor