Three separate networks run through your leg, doing three different jobs. Almost every confusing symptom below the knee becomes clearer once you know which one you are dealing with.
Arteries: the delivery system
Arteries carry oxygen-rich blood away from the heart. In the leg, blood travels from the aorta into the pelvis, down the thigh, behind the knee, and into progressively smaller vessels until it reaches the toes. The system runs under pressure — that is what a pulse is.
When arteries fail: plaque narrows them and less blood gets through. The shortfall shows first when demand rises, which is why the classic symptom is leg pain during walking rather than at rest. Later, the shortfall shows at rest too. Tissue starved of arterial blood does not heal, which is why a wound that will not close is so often an arterial question.
The tell: arterial symptoms get worse with activity, and raising the leg makes matters worse rather than better — people with advanced disease hang the foot out of bed at night.
Veins: the return system
Veins carry blood back to the heart, and in the leg they have to do it against gravity. They manage that with three helpers: the calf muscles squeezing the deep veins with every step, changes in pressure from breathing, and a series of one-way valves that stop blood falling back between squeezes.
When veins fail: the valves become leaky, blood refluxes downward, and pressure in the lower leg stays high. High venous pressure pushes fluid into the tissue, and over years it changes the skin — itching, brown staining, thickening, and eventually ulceration.
The tell: venous symptoms get worse the longer you are upright and better when the leg is raised. Swelling that is present in the evening and gone by morning is close to a signature.
Lymphatics: the drainage system
The third network is the one most people have never heard of. Fluid constantly leaks out of small blood vessels into the tissue, carrying protein with it. Lymph vessels collect that fluid, filter it through lymph nodes, and return it to the bloodstream. Unlike the heart-driven blood circulation, lymph moves largely through muscle movement and small rhythmic contractions of the vessels themselves.
When lymphatics fail: if vessels or nodes are missing, damaged — by surgery, radiotherapy, infection or injury — or simply overwhelmed, protein-rich fluid stays in the tissue. That is lymphedema. Because the fluid is protein-rich, it draws more fluid in and over time the tissue becomes firmer rather than softer.
The tell: swelling that includes the foot and toes, does not resolve overnight the way venous swelling does, and eventually feels firm rather than squashy. Difficulty pinching up the skin at the base of the second toe is a classic clinical sign.
Side by side
| Arteries | Veins | Lymphatics | |
|---|---|---|---|
| Job | Deliver blood | Return blood | Drain tissue fluid |
| Direction | Toward the foot | Toward the heart | Toward the trunk |
| Driven by | The heart | Calf pump, valves, breathing | Movement and vessel contraction |
| Worse with | Walking, exertion | Standing, time upright | Time, heat, infection |
| Elevation | Can worsen pain | Helps | Helps less once established |
| Typical swelling | Not a feature | Soft, evening, better by morning | Firmer, includes toes, persistent |
| Skin over time | Thin, shiny, hairless; wounds on toes and pressure points | Brown staining, eczema, ulcers at the inner ankle | Thickened, warty texture, deep skin folds |
| Compression | Can be harmful | A mainstay | A mainstay, specialist-guided |
They coexist more often than they take turns
Real legs do not read the table. Someone can have arterial narrowing and venous reflux at the same time, with nerve damage on top — which is common in diabetes. That combination is exactly why measurement matters: a leg with both problems needs the arterial supply quantified before anyone decides how much compression is safe.
Common questions
Which system causes swelling?
Veins and lymphatics both can, and so can the heart, kidneys, liver and a long list of medicines. Arteries are the one that typically does not — arterial disease causes pain, coldness, poor healing and skin change, not swelling. So a swollen leg is rarely an arterial story on its own.
Why does compression help veins but harm arteries?
Compression squeezes the leg from outside. For the venous system that is a help — it supports the vessels carrying blood upward and pushes fluid back in. For the arterial system it is opposition: arterial blood has to get into the leg against that external pressure. If arterial flow is already marginal, adding external pressure can reduce it further.
What is the calf pump?
The calf muscles wrapped around the deep veins. Every step squeezes them and pushes blood upward, and the valves stop it falling back. It is why walking helps venous problems and why standing still for long periods is worse than either walking or sitting.
Does “poor circulation” mean arteries?
People usually say it about cold feet, swelling or discoloration, and most of those have nothing to do with arteries. It is a phrase worth retiring in favor of naming which system you mean, because the treatments genuinely conflict.
Where to go next
Sources
- National Heart, Lung, and Blood Institute. Peripheral Artery Disease.
- Society for Vascular Surgery. Chronic Venous Insufficiency.
- NHS. Lymphoedema.
- National Cancer Institute. Lymphedema.
Written by Tom Biernacki, DPM, FACFAS. Published 20 September 2026. General education, not medical advice.