Applied Anatomy of Arteries & Veins of Limbs
Week 23
Understand the concepts and associated principles, functional & clinical application of:
9. The site of:
(i)
great saphenous vein ‘cut down’ (noting the structures endangered);
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Venous cutdown is an emergency procedure to get vascular access, in which the
vein is exposed surgically and then a cannula is inserted into the vein under
direct vision for prolomged administration of blood, plasma expanders,
electrolytes or drugs
even when it is not visible in infants and obese people, or in patients who are in
shock and whose veins have collapsed, the great saphenous vein can always be
located by making a skin incision anterior to the medial malleolus
also, its location distant from the primary resuscitative efforts centered at the
head, neck, and torso allow for unhindered accessibility to the site
the saphenous nerve accompanies the great saphenous vein anterior to the
medial malleolus. Should this vein be cut during a saphenous cutdown or
caught by a ligature when closing the wound, the patient may complain of pain
along the medial border of the foot
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(ii)
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The great saphenous vein is formed from the union of
the dorsal vein of the great toe and the dorsal venous
arch of the foot
it ascends anterior to the medial malleolus
passes posterior to the medial condyle if the femur
anastomoses freely with the small saphenous vein
traverses the saphenous opening in the fascia lata
empties into the femoral vein
femoral artery and femoral vein punctures
the superficial position of the femoral artery in the femoral triangle, makes it vulnerable
to punctures by lacerations and gunshot wounds
commonly both the femoral artery and vein are lacerated in anterior thigh wounds
because they lie so close together
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in some cases an arteriovenous shunt occurs as a result of communication between the
two vessels
when it is necessary to ligate the femoral artery, the cruciate anastomosis supplies
blood to the lower limb
cruciate anastomosis -formed between the medial and lateral circumflex femoral
arteries with the inferior gluteal artery superiorly and tnhe 1st perforating artery
inferiorly)
10. The sites, diagnosis and effects of:
(i)
varicose veins (noting the significance of incompetence of the valves of the
perforating veins)
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(ii)
a varicose vein (or varix) is an abnormal dilatation of a vein which may also become
elongated and tortuous
tend to become more prominent with prolonged elevation of venous pressure
structural damage to valve cusps (e.g. from venous thrombosis) may result in
venous valve incompetence
the valves fail to close allowing blood flow in the opposite direction
incompetent valves of perforating veins in the leg are particularly significant as the
muscular venous pump shunts blood back under pressure from deep veins
(surrounded by the calf muscles) to superficial veins (not surrounded by muscles)
where the blood pools
dilatation of a vein at the site of a valve may also result in impairment of valve
function with the potential for a domino effect along the vein
occurs especially in long veins subject to high hydrostatic pressure (e.g. in the leg)
varicose veins may therefore be both the cause and the effect of valve
incompetence
deep vein thrombosis
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thrombus = blood clot on vascular system of living person
deep veins of the calf are predisposed to thrombosis if surrounding muscles are
not contracting regularly
stasis and pooling of blood in soleal venous sinuses occurs if not emptied
regularly by contraction of the calf muscles
a thrombus in a deep calf vein (especially one that propagates proximally), may
dislodge (or part of it may break off) to become a thromboembolus
pulmonary embolism is a potential consequence of a DVT originating in the calf
and is life-threatening
thromboemboli are carried via the IVC and right side of the heart to the
pulmonary arterial system
one or more arteries subsequently become occluded as they become
successively narrower by branching
thromboemboli are more common in veins that arteries due to the more
sluggish flow
11. How an infection of a toe may produce a painful swelling in the groin
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the lower limb has superficial and deep lymphatic vessels
the superficial accompany the saphenous veins and their tributaries
the lymphatics accompanying the great saphenous vein (remember part of this
vein originates in the big toe) end in the superficial inguinal lymph nodes
lymph nodes enlarge when diseased and pathogenic micro-organisms or their
toxins in the blood or other tissues, may produce slight enlargement of the
superficial inguinal lymph nodes
because these nodes are in the subcutaneous tissue they are easy to palpate in
normal people
an infection in the big toe could therefore travel up the superficial lymphatics
until it reached the superficial inguinal nodes and cause a swelling there
12. The structures involved in the differential diagnosis of a ‘lump’ in the femoral triangle
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femoral hernia
enlarged lymph nodes