Venous Pump of the Lower Limb-Varicose Veins

Venous Pump of the Lower Limb

Within the closed fascial compartments of the lower limb, the thinwalled, valved venae comitantes are subjected to intermittent pressure at rest and during exercise. The pulsations of the adjacent arteries help move the blood up the limb. However, the contractions of the large muscles within the compartments during exercise compress these deeply placed veins and force the blood up the limb.

The superficial saphenous veins, except near their termination, lie within the superficial fascia and are not subject to these compression forces. The valves in the perforating veins prevent the high-pressure venous blood from being forced outward into the low-pressure superficial veins. Moreover, as the muscles within the closed fascial compartments relax, venous blood is sucked from the superficial into the deep veins.

Varicose Veins

A varicosed vein is one that has a larger diameter than normal and is elongated and tortuous. Varicosity of the esophageal and rectal veins is described elsewhere.

This condition commonly occurs in the superficial veins of the lower limb and, although not life threatening, is responsible for considerable discomfort and pain.

Varicosed veins have many causes, including hereditary weakness of the vein walls and incompetent valves; elevated intraabdominal pressure as a result of multiple pregnancies or abdominal tumors; and thrombophlebitis of the deep veins, which results in the superficial veins becoming the main venous pathway for the lower limb. It is easy to understand how this condition can be produced by incompetence of a valve in a perforating vein. Every time the patient exercises, high-pressure venous blood escapes from the deep veins into the superficial veins and produces a varicosity, which might be localized to begin with but becomes more extensive later. The successful operative treatment of varicosed veins depends on the ligation and division of all the main tributaries of the great or small saphenous veins, to prevent a collateral venous circulation from developing, and the ligation and division of all the perforating veins responsible for the leakage of highpressure blood from the deep to the superficial veins. It is now common practice to remove or strip the superficial veins in addition.

Needless to say, it is imperative to ascertain that the deep veins are patent before operative measures are taken.

Arterial Injury of the upper limb-Palpation and Compression of Arteries-Allen Test-Arterial Innervation and Raynaud’s Disease-

Arterial Injury of the upper limb

The arteries of the upper limb can be damaged by penetrating wounds or may require ligation in amputation operations.

Because of the existence of an adequate collateral circulation around the shoulder, elbow, and wrist joints, ligation of the main arteries of the upper limb is not followed by tissue necrosis or gangrene, provided, of course, that the arteries forming the collateral circulation are not diseased and the patient’s general circulation is satisfactory. Nevertheless, it can take days or weeks for the collateral vessels to open sufficiently to provide the distal part of the limb with the same volume of blood as previously supplied by the main artery.

Palpation and Compression of Arteries

A clinician must know where the arteries of the upper limb can be palpated or compressed in an emergency. The subclavian artery, as it crosses the first rib to become the axillary artery, can be palpated in the root of the posterior triangle of the neck. The artery can be compressed here against the first rib to stop a catastrophic hemorrhage. The third part of the axillary artery can be felt in the axilla as it lies in front of the teres major muscle. The brachial artery can be palpated in the arm as it lies on the brachialis and is overlapped from the lateral side by the biceps brachii.

The radial artery lies superficially in front of the distal end of the radius, between the tendons of the brachioradialis and flexor carpi radialis; it is here that the clinician takes the radial pulse. If the pulse cannot be felt, try feeling for the radial artery on the other wrist; occasionally, a congenitally abnormal radial artery can be difficult to feel. The radial artery can be less easily felt as it crosses the anatomic snuffbox.

The ulnar artery can be palpated as it crosses anterior to the flexor retinaculum in company with the ulnar nerve. The artery lies lateral to the pisiform bone, separated from it by the ulnar nerve. The artery is commonly damaged here in laceration wounds in front of the wrist.

Allen Test

The Allen test is used to determine the patency of the ulnar and radial arteries. With the patient’s hands resting in the lap, compress the radial arteries against the anterior surface of each radius and ask the patient to tightly clench the fists. The clenching of the fists closes off the superficial and deep palmar arterial arches. When the patient is asked to open the hands, the skin of the palms is at first white, and then normally the blood quickly flows into the arches through the ulnar arteries, causing the palms to promptly turn pink. This establishes that the ulnar arteries are patent. The patency of the radial arteries can be established by repeating the test but this time compressing the ulnar arteries as they lie lateral to the pisiform bones.

Arterial Innervation and Raynaud’s Disease

The arteries of the upper limb are innervated by sympathetic nerves. The preganglionic fibers originate from cell bodies in the 2nd to 8th thoracic segments of the spinal cord. They ascend in the sympathetic trunk and synapse in the middle cervical, inferior cervical, 1st thoracic, or stellate ganglia. The postganglionic fibers join the nerves that form the brachial plexus and are distributed to the arteries within the branches of the plexus.

For example, the digital arteries of the fingers are supplied by postganglionic sympathetic fibers that run in the digital nerves. Vasospastic diseases involving digital arterioles, such as Raynaud’s disease, may require a cervicodorsal preganglionic sympathectomy to prevent necrosis of the fingers. The operation is followed by arterial vasodilatation, with consequent increased blood flow to the upper limb.

Development of the Upper Limb-Amelia-Congenital Absence of the Radius-Syndactyly-Lobster Hand-Brachydactyly-Floating Thumb-Polydactyly-Local Gigantism

Development of the Upper Limb

The limb buds appear during the sixth week of development as the result of a localized proliferation of somatopleuric mesenchyme. This causes the overlying ectoderm to bulge from the trunk as two pairs of flattened paddles. The arm buds develop before the leg buds and lie at the level of the lower six cervical and upper two thoracic segments. The flattened limb buds have a cephalic preaxial border and a caudal postaxial border. As the limb buds elongate, the anterior rami of the spinal nerves situated opposite the bases of the limb buds start to grow into the limbs.

The mesenchyme situated along the preaxial border becomes associated and innervated with the lower five cervical nerves, whereas the mesenchyme of the postaxial border becomes associated with the 8th cervical and 1st thoracic nerves.

Later, the mesenchymal masses divide into anterior and posterior groups, and the nerve trunks entering the base of each limb also divide into anterior and posterior divisions. The mesenchyme within the limbs differentiates into individual muscles that migrate within each limb. As a consequence of these two factors, the anterior rami of the spinal nerves become arranged in complicated plexuses that are found near the base of each limb so that the brachial plexus is formed.

Amelia

Absence of one or more limbs (amelia) or partial absence (ectromelia) may occur. A defective limb may possess a rudimentary hand at the extremity of the limb or a well-developed hand may spring from the shoulder with absence of the intermediate portion of the limb (phocomelia) .

Congenital Absence of the Radius

Occasionally, the radius is congenitally absent and the growth of the ulna pushes the hand laterally.

Syndactyly

In syndactyly, there is webbing of the fingers. It is usually bilateral and often familial. Plastic repair of the fingers is carried out at the age of 5 years.

Lobster Hand

Lobster hand is a form of syndactyly that is associated with a central cleft dividing the hand into two parts. It is a heredofamilial disorder, for which plastic surgery is indicated where possible.

Brachydactyly

In brachydactyly, there is an absence of one or more phalanges in several fingers. Provided that the thumb is functioning normally, surgery is not indicated .

Floating Thumb

A floating thumb results if the metacarpal bone of the thumb is absent but the phalanges are present. Plastic surgery is indicated where possible to improve the functional capabilities of the hand.

Polydactyly

In polydactyly, one or more extra digits develop. It tends to run in families. The additional digits are removed surgically.

Local Gigantism

Macrodactyly affects one or more digits; these may be of adult size at birth, but the size usually diminishes with age. Surgical removal may be necessary.