VASCULAR ANATOMY OF THE EXTREMITIES

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CHAPTER 62 VASCULAR ANATOMY OF THE EXTREMITIES

Enrique Ginzburg, Chee Kiong Chong, Norman M. Rich

Extremity vascular injuries date as far back as the Greek and Roman civilization. Much of the knowledge regarding vascular trauma and the management of these injuries was gained from military conflicts. DeBakey and Simeone reported the amputation rate to be as high as 40% in World War II, when it was the main life-saving measure for soldiers who sustained extremity injuries. With the advance in surgical technologies and techniques, the rate of amputation dropped to as low as 15% during the Korean War. All this information provides modern surgeons with the ability to manage vascular trauma without the need to enter a combat zone.

DIAGNOSIS

Most patients that are admitted to a trauma center with extremity vascular injuries will be admitted from penetrating trauma. These are usually either stab wounds from knives or low velocity bullet wounds. In most cities, this is closely followed by patients who sustain blunt injuries as a result of motor vehicle crashes, and these are often associated with long bone fractures.

There are hard and soft clinical signs of vascular trauma. The hard signs include the following:

Pulsatile bleeding
Absence of pulses
Distal ischemia
Visible expanding or pulsatile hematoma
Presence of a thrill or bruit over the injured site

The soft signs of vascular injury include the following:

Bony injury
Proximity of penetrating wound
Presence of significant hemorrhage but stopped
Neurologic deficit
Well-contained hematoma
Swelling out of proportion to the injury

Patients with hard signs of vascular injury will undergo mandatory surgical exploration, as any delay will increase the risk of amputation, reperfusion injury, compartmental syndrome, and infection. The management of patients with soft signs will usually include further diagnostic studies, close observation, and frequent re-examination. Diagnostic studies include Doppler ultrasound, computed tomography (CT) angiogram, or conventional angiography.

MANAGEMENT

The management of patients appearing with obvious peripheral vascular injuries should follow the protocols outlined by Advance Trauma Life Support (ATLS). Airway, breathing, and circulation will take priority. Injury to the brain, chest, and abdomen will also usually take precedence over extremity hemorrhage, which can usually be controlled by direct pressure.

Successful management of extremity vascular injury includes the following components:

Prompt resuscitation
Control of hemorrhage, usually with direct pressure
Timely diagnosis
Early surgical exploration
Minimized delay in transporting patient to operating room or extensive diagnostic studies when not indicated

A thorough knowledge of the relevant anatomy of the extremity is very important during surgical exploration. Destruction or distortion of tissue planes by hemorrhage is usually the rule rather than the exception, and when this is coupled with the retraction of the vessels into the surrounding tissue, it will increase the difficulty of achieving proximal and distal control of the bleeding vessel, which is the most important step in stopping the bleeding.

VASCULAR ANATOMY OF UPPER EXTREMITY

Axillary Artery

The axillary artery starts from the lateral border of the first rib, as a direct continuation of the subclavian artery. It enters the axilla at the apex and crosses the first intercostal space to run along the lateral wall of the axilla. As the artery emerges from beneath the costoclavicular passage, it becomes closely related to the brachial plexus, divisions, and cords. These nerves surround the artery and exchange fibers to eventually become the median, ulnar, and radial nerves at the distal portion of the axillary artery. This neurovascular bundle is enclosed in the axillary sheath, which separates it from the axillary vein. Distally, the axillary artery continues on as brachial artery at the lateral edge of the teres major muscle tendon.

Anteriorly, the axillary artery follows a course under the pectoralis minor muscle as it inserts into the coracoid process. The muscle divides the artery into three anatomical portions:

The first portion runs from lateral edge of the first rib to the upper border of the tendon pectoralis minor muscle, behind the clavipectoral fascia and the clavicular head of the pectoralis major muscle. It has only one branch in this portion, the supreme thoracic artery.

The second portion lies behind the pectoralis minor muscle. This is the shortest portion and it has two branches of clinical significance, the thoracoacromial artery and the lateral thoracic artery. The cords of the brachial plexus surround the axillary artery at this section.

The third portion starts from the lateral border of the pectoralis muscle to the lateral border of the teres major muscle. The axillary artery gives out three branches at the portion, the subscapular artery, the lateral humeral circumflex artery, and the medial circumflex artery. At this level, the brachial plexus becomes the medial nerve, which is anterior, the radial nerve, which is posterior, and the ulnar nerve, which is inferior to the axillary in the axillary sheath.

Axillary Vein

The basilic vein continues on at the lower edge of the teres major muscle as the axillary vein. Its main tributaries are brachial veins, which accompany the named arteries while they ascend in the axilla, and the cephalic vein, which courses through the deltopectoral groove, just below the clavicle. The axillary vein then becomes the subclavian vein above the lateral border of the first rib.

The axillary vein lies medial to the axillary artery. It is separated from artery by the medial pectoral nerve, medial cord of the brachial plexus, and the ulnar nerve. It is separated from the axillary sheath by a pad of fat. The close proximity of the vein to the artery often results in the occurrence of traumatic arteriovenous malformations. Penetrating injury to the upper part of axilla can cause profuse hemorrhage and risk of air embolism.

Surgical Exposure of Axillary Vessels

The axillary artery lies anterior to the capsule of the shoulder joint and might be injured when the shoulder is dislocated anteriorly. Fractures of the surgical neck of the humerus will also risk lacerating the vessel as it runs over the fusion of the subscapularis tendon and the joint capsule.

The axillary artery can be exposed through an infraclavicular incision placed 2 cm below and parallel to the mid-point of the clavicle, following a gentle curve along the anterior axillary line and then along the anterior border of the deltoid muscle. The first portion of the artery is the simplest to expose because it is medial to the pectoralis muscle and contains only one branch. Exposure of the second portion will require the detachment of the pectoralis minor tendon from the coracoid process. The cords of the brachial plexus surround this portion of the axillary artery, arranged medially, laterally, and posteriorly. From the posterior cord arises the axillary nerve, which follows a posterolateral course on the neck of the humerus. This nerve can be easily injured by dislocation of the humerus or fracture of the surgical neck, causing atrophy of the deltoid muscle and numbness of an area over the deltoid region. The third portion becomes superficial after emerging from under the pectoralis major muscle before becoming the brachial artery. Great care must be taken while exposing this portion because the nerves to the upper extremities run about it. The median nerve runs anterior to the artery and is frequently involved in axillary injuries resulting from its superficial position.

Brachial Artery

The brachial artery originates at the lower border of the teres major muscle as a direct continuation of the axillary artery. It takes a course toward the antecubital fossa, together with the median nerve, and bifurcates into radial and ulnar arteries opposite the neck of the radius. The medial bicipital sulcus, which separates the coracobrachialis and biceps muscle anteriorly from the triceps muscle posteriorly, marks the course of the basilic vein toward the axillary vein and provides the surface marking of the brachial vessels.

The proximal part of the brachial artery lies on the medial aspect of the arm, anterior to the long and median head of the triceps and bordered laterally by the coracobrachialis muscle. The median nerve lies between the coracobrachialis muscle and the brachial artery, whereas the ulnar nerve separates the artery from the basilic vein. The brachial artery gives rise to the profunda brachii artery posteriorly, which passes backward and accompanies the radial nerve in the radial groove to the lateral condyle of the humerus. This artery collateralizes about the shoulder with the circumflex humeral arteries arising from the axillary artery.

The brachial artery gradually inclines forward and outward and eventually comes to lie below the medial border of the biceps muscle. The median nerve crosses the artery obliquely at this part of the arm. The basilic vein and the medial cutaneous nerve are separated from the artery by the deep fascia sheath. The branches arising from this portion of the brachial artery include the nutrient artery to the humerus, muscular branches, and superior ulnar collateral artery, which accompanies the ulnar nerve to the groove on the posterior surface of the medial epicondyle. This artery subsequently takes part in the rich anastomosis around the elbow joint.

The distal part of the brachial artery is overlapped by the medial border of the biceps muscle and biceps tendon and eventually comes to lie medial to the biceps tendon before the bifurcation of the artery. The median nerve lies medial to the brachial artery. This inferior ulnar collateral artery arises near the elbow and forms a rich network of collaterals around the elbow joint. Brachial artery bifurcates opposite the neck of the radius bone to give rise to the ulnar artery medially and the radial artery laterally.

The artery is closely accompanied by a pair of venae comitantes that drain into the axillary vein.

Surgical Exposure of Brachial Artery

The brachial artery is the most commonly injured artery in the upper extremity, probably as a result of the superficial course that it takes. This artery accounts for 50% of all upper extremity injuries.

In the arm, exposure in any part of the artery can be achieved by a longitudinal incision along the course of the vessel just medial to the bicipital sulcus. This sulcus can be easily identified by grasping the head of the biceps and lifting it up to reveal the groove. The artery, along with the accompanying vein and nerves, is immediately visible after dividing the skin and subcutaneous tissue, investing the fascia, and splitting the biceps and triceps muscle. The basilic vein runs a superficial course along the bicipital sulcus. It can be identified and retracted laterally to prevent injury to the vein.

Just above the elbow, the brachial artery passes behind the bicipital aponeurosis, which may be divided to facilitate exposure of the vessel. The brachial artery is juxtaposed to the median nerve. Extension of incision across the antecubital fossa should be made with an S-shaped incision to reduce the risk of joint contracture. Care has to be exercised to prevent injury to the accompanying nerves and veins.

Radial Artery

The radial artery is usually the smaller branch that follows the general direction of the brachial artery. It is a fairly superficial vessel, covered mainly by skin, subcutaneous tissue, and fascia, save for the upper part, which is covered by the fleshy belly of brachioradialis muscle. The artery takes a course that travels laterally gradually, and after emerging from under the brachioradialis muscle, it comes to lie between the brachioradialis and the flexor carpi radialis muscles. The distal part, which is the most superficial part of the radial artery, travels between the tendon of flexor pollicis longus and the lateral border of the radius, until it passes behind the flexor retinaculum to enter the hand.

The radial artery gives rise to two major branches, the radial recurrent branch near the origin, and the superficial palmar branch, which takes part in the formation of the superficial palmar arch.

Ulnar Artery

The ulnar artery is the larger of the two terminal trunks of the brachial artery. It runs downward and medially to reach the medial aspect of the forearm from the bifurcation. During its course, the artery lies on the brachialis muscle in the upper part and then on the flexor digitorum profundus as it progresses distally. It is covered by the pronator teres muscle, flexor carpi radialis, and flexor digitorum superficialis. The medial nerve lies medial to the ulnar artery for the first 2.5 cm before it crosses in front of the artery to take up a lateral relationship. After the crossing over, the nerve is separated from the artery by the ulnar head of the pronator teres.

At the distal part, the ulnar artery emerges between the tendon of the flexor digitorum superficialis medially and flexor carpi ulnaris laterally to be covered by skin and fascia only. It subsequently passes behind the palmaris brevis to terminate in the superficial palmar arch. The branches that give out near the origin of the ulnar artery include the anterior and posterior ulnar recurrent arteries and the common interosseous artery.

Surgical Exposure of Ulnar and Radial Arteries

The incidence of ulnar and radial artery injuries ranges from 7%–35% of all upper extremity injuries. Ligation of a single vessel results in an amputation rate of 10%. Ligation of both vessels increases the rate to 39%.

Exposure of the ulnar artery is made through an incision over the medial volar aspect of the forearm, over the course of the vessel. The incision can be extended proximally to reach the antecubital fossa to gain control of the brachial artery. The skin incision is deepened to the subcutaneous, and the tissue between flexor carpi radialis and flexor digitorum superficialis can be split to facilitate exposure.

The radial artery can be exposed throughout its length via a longitudinal incision made on the medial aspect of the brachioradialis muscle. This will allow lateral retraction of the muscle to facilitate exposure. The artery runs superficially at the wrist, and exposure over the wrist will only require division of skin and subcutaneous tissue over the pulsation. However, this artery is very liable to spasm. Papaverine can be used to infiltrate the radial sheath, which is the deep fascia, before sharp dissection and mobilization.

VEINS OF UPPER EXTREMITY

The upper limb has deep and superficial sets of draining veins. The deep veins are the venae comitantes of the named arteries. The superficial vein runs in between the superficial fascia immediately beneath the skin. These two set of vessels have frequent anastomosis with each other.

In the forearm, the named arteries are accompanied by a pair of venae comitantes to provide venous drainage. These deep veins will drain into the two brachial veins. The brachial veins run with the brachial artery in the arm, draining blood proximally, until they join the axillary vein at the lower border of the subscapularis muscle.

The upper extremity also has a superficial venous network to provide drainage of the upper limb. These veins will eventually drain into the superficial veins, namely the basilic and cephalic veins.

Basilic Vein

The basilic vein receives tributaries from the ulnar component of the dorsal venous network. It runs up the posterior surface of the forearm and curves around the ulnar border below the elbow to the anterior surface of the forearm. In the elbow, it is joined by the vena mediana cubiti, a branch from the cephalic vein. The vein takes a medial and superficial relation to the brachial artery and the medial cutaneous nerve in this part of the course. It then runs upward along the medial border of the biceps brachii muscle, and perforates the deep fascia to run along the medial side of the brachial artery. At the lower border of the teres major muscles, the vein continues on as the axillary vein.

Cephalic Vein

The cephalic vein begins as the coalescence of the radial part of the dorsal venous network and winds upwards around the radial border. In the antecubital fossa just below the elbow, the cephalic vein gives off the vena mediana cubiti, which receives a perforating branch from the deep veins of the forearm and passes across to join the basilic vein. In the elbow, it crosses superficial to the musculocutaneous nerve and ascends along the lateral border of the biceps brachii muscle. In the upper part of the arm, the cephalic vein runs in the deltopectoral groove, where it is accompanied by the deltoid branch of the thoracoacromial artery. It then pierces the clavipectoral fascia to drain into the axillary vein just below the clavicle.

Axillary Vein

The basilic vein continues on at the lower edge of the teres major muscle as the axillary vein. Its main tributaries are brachial veins, tributaries that accompany the named arteries, while it ascends in the axilla, and the cephalic vein, which courses through the deltopectoral groove, just below the clavicle. The axillary vein then becomes the subclavian vein above the lateral border of the first rib.

The axillary vein lies medial to the axillary artery. It is separated from the artery by the medial pectoral nerve, medial cord of the brachial plexus, and the ulnar nerve. It is separated from the axillary sheath by a pad of fat. The close proximity of the vein to the artery often results in the occurrence of traumatic arteriovenous malformations. Penetrating injury to the upper part of axilla can cause profuse hemorrhage and risk of air embolism.

NERVES OF UPPER EXTREMITY

The nerves in the upper extremity have a close and important relationship to the major named artery. They can be easily injured along with the vessels in any trauma. However, iatrogenic injury to the nerve can also occur during surgical exploration if the relevant anatomy of the neurovascular bundle is not thoroughly understood.

Median Nerve

The median nerve originates from the lateral and medial cords of the brachial plexus at the distal part of the axillary artery. It accompanies the brachial artery throughout the whole course.

At first, the nerve lies laterally to the brachial artery. At the level of insertion of the coracobrachialis muscle, the median nerve crosses the artery superficially, occasionally deep to it, and descends along the medial side to the elbow. It traverses the cubital fossa together with the brachial artery in the same relationship, behind the aponeurosis of the biceps muscle and anterior to the brachialis muscle. It then passes into the forearm between the two heads of the pronator teres muscle, separated from the ulnar artery by the deep head of the muscle.

In the forearm, the median nerve runs between the flexor digitorum superficialis and flexor digitorum profundus, attaching firmly to the undersurface of the superficial flexor muscle of the fingers. There is no direct relationship between the median nerve and any of the major axial vessels in the forearm. At the wrist region, the median nerve lies superficially and thus prone to even minor laceration. It takes a course between the tendon of the palmaris longus and the tendon of flexor carpi radialis, and enters the wrist through the carpal tunnel along with tendons of flexor digitorum superficialis.

Ulnar Nerve

The ulnar nerve arises from the medial cord of the brachial plexus. It runs medial to the axillary artery in the axilla between the artery and the vein. In the arm, it accompanies the brachial artery on its medial side, anterior to the triceps muscle. At the distal half of the arm, the nerve deviates from the artery and pierces the medial intermuscular septum. It then runs downward and medially in the posterior compartment anterior to the medial head of the triceps muscle.

The nerve continues into the elbow between the medial epicondyle of the humerus and the olecranon. In the epicondyle groove, the nerve is just covered by skin and adipose tissue. It can be palpated as a cord-like structure and is prone to injury from any trauma to the medial epicondyle. Violent flexion of the elbow can also dislocate the nerve, and this will require surgical intervention. Through the ulnar groove on the medial epicondyle, the ulnar nerve enters the forearm between the two heads of flexor carpi ulnaris. It descends on top of the flexor digitorum profundus muscle and is overlapped by the flexor carpi ulnaris. In the upper half of the forearm, the ulnar nerve is still separated from the ulnar artery, but the two structures eventually come to travel together in the lower half of the forearm, with the nerve taking a medial relation to the artery throughout.

Radial Nerve

The radial nerve is the direct continuation of the posterior cord of the brachial plexus. It lies posterior to the axillary artery, and it is bigger in size when compared with the ulnar nerve. In the axilla, the radial nerve can be injured from prolonged exposure to pressure, such as falling asleep when the arm drapes across an arm rest and improper use of crutches. The nerve maintains the same relationship with the proximal part of the brachial artery, between the long head of the triceps and the shaft of the humerus. It then winds backward, accompanied by the profunda brachii artery, to run in the radial groove of the humerus laterally and distally across the back of the arm. The radial nerve is especially prone to injury in fracture of the midshaft of humerus resulting from its relation to the bone. Just distal to the midshaft, the nerve traverses the lateral muscular septum to enter the anterior brachii compartment, lying along the lateral margin of the brachialis muscle and deep to the brachioradialis and extensor carpi radialis longus muscle. The radial nerve may be injured in the fracture of the shaft of humerus or involved in the callus formation when the bone heals. These might need surgical intervention for repair or release of the nerve. Anterior to the lateral epicondyle, the nerve gives rise to the posterior interosseous nerve.

In the forearm, the radial nerve descends deep to the brachioradialis, to take up a lateral relationship to the radial artery in the middle third of the forearm. The neurovascular bundles course further distally before separating prior to the styloid process of the radius to enter the dorsum of the hand. The posterior interosseous branch is a muscular branch that winds around the neck of the radius through the supinator muscle. It runs between the superficial and deep muscles of the back of the forearm to innervate them. As it is in close relation to the head of radius, the posterior interosseous nerve is prone to injury from fractures of the elbow or from exposure of the elbow during surgery.

VASCULAR ANATOMY OF LOWER EXTREMITY

Femoral Artery

The femoral artery, also known as the common femoral artery, is the direct continuation of the external iliac artery. It enters the femoral triangle behind the inguinal ligament, midway between the anterior superior iliac spine and the symphysis pubis.

The femoral triangle is bounded by the inguinal ligament superiorly, medial border of the sartorius muscle laterally, medial border of adductor longus, and pectineus muscle medially. The floor of the triangle is formed by the iliacus, psoas major, pectineus, and adductor longus muscles.

Within the triangle, the femoral artery is related laterally to the femoral nerve, medially to the femoral vein and femoral canal, and posteriorly to the psoas and pectineus muscles. Early in its course, the femoral artery gives rise to several branches—superficial epigastric, superficial circumflex iliac, superior geniculate, superficial, and deep external pudendal arteries. After traveling about 4 cm, the artery bifurcates within the femoral triangle into superficial femoral artery and profunda femoris artery.

Profunda Femoris Artery

The profunda femoris artery provides the main blood supply to the thigh. It usually arises from the posterolateral aspect of the femoral artery and descends first laterally, and then posterior to the superficial femoral artery. Subsequently, the artery runs down the thigh deep to the adductor longus muscle, in close relation to the linea aspera of the femur, and pierces the adductor magnus muscle to become the fourth perforating artery.

The medial and lateral circumflex femoral arteries arise soon after the origin of the profunda femoris artery, although they branch out from the common femoral artery at the level of bifurcation in 20% of patients. These important vessels can flow in either direction. They serve as collaterals via cruciate anastomosis around the hip when either the internal or external iliac artery is occluded. Three perforating arteries are also given out along the course of the profunda femoris artery to supply the muscle of the thigh. They are also connected by a rich anastomotic network.

Superficial Femoral Artery

This is usually the larger of the two terminating branches. It exits the femoral triangle at the apex and descends into the adductor canal. This canal is bordered by the sartorius muscle medially, vastus medialis anterolaterally, and the adductor longus and magnus muscles posteriorly. Within the canal, the artery is bound closely to the femoral vein by connective tissue. The saphenous nerve lies anterior to the vessel. The artery then pierces the adductor magnus at the adductor hiatus to become the popliteal artery. Near its termination, the superior geniculate artery branches from the femoral artery.

Surgical Exposure of Femoral Artery

In both wartime and peacetime, injuries to the femoral artery account for 20%–45% of all extremity injuries. Most of the injuries are penetrating in nature. Generally, penetrating injuries are most obvious and surgical intervention can be carried out without extensive diagnostic evaluation. However, blunt injuries are frequently obscured by concomitant injuries to the bone, nerve, and soft tissues. Angiography is known as the gold standard for diagnosing vascular injury. However, with the advance in technology, CT angiography is beginning to replace conventional angiography as the first line of investigation in some centers. It is noninvasive, and results can be obtained quickly. In the absence of pulses or with evidence of diminished perfusion, restoration of flow must be achieved as quickly as possible.

Exposure can be achieved by placing a longitudinal incision over the femoral pulse in the femoral triangle. In the absence of a pulse, the incision can be placed inferior to the midpoint between anterior superior iliac spine and pubic tubercle. Proximal control of the external iliac artery can be achieved through either a separate incision that runs parallel to the inguinal ligament or by extending the longitudinal incision superiorly and laterally through the inguinal ligament.

The incision is deepened to expose the deep fascia covering the femoral triangle. Incision of the fascia will allow the retraction of sartorius and adductor magnus to expose the femoral sheath. The sheath is then sharply incised to expose the femoral artery within. Exposure of the femoral vein is carried out in similar fashion.

The superficial femoral artery can be approached through an incision along the line joining the anterior superior iliac spine and medial femoral condyle. The incision is deepened through the superficial fascia, carefully retracting the greater saphenous vein. The fascia covering of the sartorius is divided and the muscle can be retracted medially to expose the superficial femoral vessels with the saphenous nerve on the anterior surface.

Popliteal Artery

The popliteal artery begins at the adductor hiatus as the direct continuation of the superficial femoral artery. It travels downward and slightly laterally to go behind the distal femur to enter the popliteal fossa.

The popliteal fossa is an important anatomical area because all neurovascular structures passing from the thigh to the leg traverse this space. It is filled with tissues that offer protection to the neurovascular structure and yet allow the movement at the knee joint. This is a diamond-shaped fossa located behind the knee. The floor consists of popliteal surface of the femur above, posterior surface of the joint capsule with overlying popliteus muscle. The superior border is made up of bicep femoris muscle and tendon laterally, and four muscles (namely, semimembranosus, semitendinosus, gracilis, and sartorius muscles) medially. The inferior boundaries are formed by the lateral and medial head of the gastrocnemius muscle, respectively. The roof consists of a strong sheet of deep investing fascia, which is pierced in the center by the short saphenous vein, subcutaneous tissue, and skin. This unites with the muscles and tendons forming the boundaries to form a well-enclosed space.

The popliteal artery runs on the floor of the popliteal fossa between the condyles of the femur until it reaches the distal border of the popliteus muscle and terminates by dividing into anterior tibial and tibioperoneal trunk. Throughout the course, it is in direct contact with the posterior ligament of the knee joint. Three pairs of branches are given out to supply the knee and these form important collaterals about the knee. No branches are given off at the upper portion of the popliteal artery, and this portion of the vessel is accessible for ligation if required.

Anterior Tibial Artery

The anterior tibial artery is the smaller terminating branch of the popliteal artery that arises from the lower border of the popliteus muscle. It passes forward through the interosseous membrane into the anterior compartment of the leg. At first, it lies close to the medial aspect of the neck of the fibula, but inclines medially and forward on the membrane as it descends and rests against the anterior surface of the shaft of tibia in the lower third of the leg. It lies deep between anterior tibialis and extensor digitorum longus muscle proximally and extensor hallucis longus muscle distally. In the final part of its course, it is covered only by skin, fascia, and extensor retinaculum. At the level of the ankle, the tendon of the extensor hallucis longus muscle crosses in front of the artery to become medially related. The artery then continues on as the dorsalis pedis.

Throughout the course, the anterior tibial artery is surrounded by two interlacing venae comitantes and the deep peroneal nerve. The deep peroneal nerve, after winding around the neck of the fibula, joins the anterior tibial artery soon after the artery enters the anterior compartment. Initially the nerve lies laterally to the artery, but from about the middle of the leg, the nerve takes up an anterolateral relationship with the artery for the rest of its course.

Tibioperoneal Trunk

The tibioperoneal trunk is the larger terminating branches of the popliteal artery. It originates and descends from just behind the soleal arch. The trunk lies on the tibialis posterior muscle and is covered by the gastrocnemius and soleus muscles. A network of complex and thin-walled venous vessels surrounds the artery and may bleed profusely during dissection of the tibioperoneal trunk. The tibial nerve accompanied the artery below the arch of the soleus muscle. It runs a variable length, ranging from 0 to 5 cm before bifurcating into posterior tibial and peroneal artery.

Posterior Tibial Artery

Posterior tibial artery is the direct continuation of the tibioperoneal trunk. It descends in the posterior compartment, lying on posterior tibialis for most of its course and covered by gastrocnemius and soleus muscles. In the upper two thirds, the posterior tibial artery lies deep to the covering muscles. For the rest of the course, the artery takes a superficial course. At its termination, the artery lies midway between the medial malleolus and the medial tubercle of the calcaneus, among the tendons of the deep leg muscles and under the cover of the flexor retinaculum. A pair of deep veins accompanies the artery as venae comitantes. Throughout the course, the posterior tibial nerve runs alongside the artery. The nerve takes a medial relationship initially and becomes posterior in the lower part of the leg. The posterior tibial artery terminates by dividing into medial and lateral plantar arteries.

Peroneal Artery

The peroneal artery descends laterally toward the fibula after branching off from the tibioperoneal trunk. It then follows the medial edge of the fibula, between flexor hallucis longus and tibialis posterior muscles, in close relation to the posterior aspect of the fibula and the interosseous membrane throughout the course. At the ankle, the artery gives off a branch that perforates the interosseous membrane. This anterior malleolar branch of the peroneal artery descends in front of the lateral malleolus, and forms an anastomotic network around the malleolus with the lateral and posterior malleolar branches of the peroneal artery. A pair of deep veins accompanies the artery, but there is no major nerve that travels with the artery.

Surgical Exposure of Vessels in Leg

Most of these injuries are blunt injuries in peacetime, as opposed to most wartime injuries, which are penetrating in nature. Popliteal artery injury remains a serious affair. The amputation rate had been high with ligation, such as up to 73% in World War II. The rate of amputation has dropped significantly over the last decade, with the advance in arterial repair and liberal use of fasciotomy and intraoperative angiography. However, vascular insufficiency is a common sequelae when the limb survives.

The approach to the popliteal artery can be carried out in a posterior or a medial incision. A posterior S-shaped incision requires the patient to be placed in a prone position and have limited access to the anterior compartment of the leg; thus, it is seldom used for vascular injury. The medial approach tends to be more versatile, and lacks the disadvantages of the posterior approach. The incision is placed from the medial femoral condyle across the knee down to the leg. The incision of the superficial fascia will expose the underlying muscles. Anterior retraction of vastus medialis muscle and posterior retraction of sartorius muscle will expose the popliteal vessels and the saphenous nerve. This incision can also be extended distally behind the bony prominence of the tibia, to approach the origin of the anterior tibial artery and the tibioperoneal trunk. The exposure can be further enhanced by dividing the medial head of the gastrocnemius muscle, the tendon of the adductor magnus, sartorius, and the two medial hamstrings muscles.

The anterior tibial artery in the anterior compartment lies in front of the interosseous membrane. Exposure can be gained by a longitudinal lateral incision between the tibia and fibula. The incision is carried through the intermuscular septum between the tibialis anterior and extensor hallucis longus muscles, without disrupting the belly of the muscles. The extensor hallucis longus can be retracted laterally to facilitate exposure. Care must be taken to preserve the venae comitantes and the deep peroneal nerve. This approach, coupled with resection of fibula, will also facilitate exposure of the peroneal vessels that lie just behind the fibula in the posterior compartment. The anterior tibial artery in the lower part of the leg lies superficially. The incision placed over the pulse, dissection of the subcutaneous tissue, and investing fascia will allow exposure of vessel.

The posterior tibial artery is accessed through a medial approach. An incision is placed behind the posterior border of the tibia. The deep investing fascia is incised for the length of the wound and the intermuscular plane between the flexor digitorum longus anteriorly, and the medial head of gastrocnemius and soleus posteriorly. This will also allow exposure of the peroneal vessels, which lie in a more lateral position. Care must be taken to avoid injuring the tibial nerve, which lies adjacent to the posterior tibial artery. In the lower third of the calf, the posterior tibial artery takes a superficial course after emerging from under the soleus and gastrocnemius muscles. It is only covered by skin, subcutaneous tissue, and the deep investing fascia. The incision can be made directly over the pulse or about an inch anterior to the Achilles tendon and deepened to expose the vessel.

VEINS OF LOWER EXTREMITY

Like the upper extremity, the veins in the lower extremity are also divided into two sets—superficial and deep veins. The deep veins accompany the named arteries. In the thigh, they are usually single veins that run alongside the major arteries, namely, the common femoral vein, the superficial femoral vein, the deep femoral vein, and the popliteal veins. Those that accompany the smaller arteries usually consist of two smaller veins, the venae comitantes. These are the main capacitance vessels of the lower extremity.

The superficial veins, much like their counterparts in the upper limb, run below the skin in between the superficial fascia. In the lower extremity, the superficial veins are the long saphenous and the short saphenous veins with their tributaries. The deep and superficial systems are connected by perforating veins at various points in the lower extremity.

Long Saphenous Vein

The long saphenous vein is the longest vein in the body. It begins in the medial marginal vein of the dorsum of the foot. The vein runs in front of the medial malleolus and along the medial side of the leg, in relation with the saphenous nerve. It curves posteriorly at the level of the knee, and then sweeps upwards along the inner aspect of the thigh. The vein enters the femoral triangle, pierces the deep fascia, passes through the fossa ovalis, and finally gains entry into the common femoral vein. Near the fossa ovalis, it is joined by the superficial epigastric, the superficial iliac circumflex, the superficial external pudendal veins, and the accessory saphenous veins.

Short Saphenous Vein

The short saphenous begins behind the lateral malleolus as a continuation of the lateral marginal vein of the foot. It firsts ascends along the lateral border of the Achilles tendon, and then crosses the tendon to continue its ascent in the midline of the back of the leg. In the lower part of the popliteal fossa, the short saphenous vein perforates the deep fascia and ends in the popliteal vein between the heads of the gastrocnemius muscle. In the lower third of the leg, the vein is in close relation with the sural nerve, and in the upper two-thirds with the medial sural cutaneous nerve.

SUGGESTED READINGS

Lumley JSP. Color Atlas of Vascular Surgery. Baltimore: Williams & Wilkins, 1986.

Nyhus LM, Baker RJ, Fischer JE, editors. Master of Surgery. Boston: Little, Brown, 1997.

Rutherford RB, editor. Vascular Surgery, 3rd ed., Philadelphia: Saunders, 1989.

Stoney RJ, Effene DJ. Comprehensive Vascular Exposures. Philadelphia: Lippincott-Raven, 1998.

Zollinger RMJr, Zollinger R. Atlas of Surgical Operations. New York: McGraw-Hill, 1993.

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