lower extremity venous anatomy Flashcards
what are the 3 layers of the venous wall?
tunica intima - inner lining, direct extension to valves
tunica media - middle, smooth muscle, thinner than artery tunica adventitia - outer, loose connective tissue, relatively thin, vaso vasorum
describe the venous valves
Semilunar / bicuspid
2 cusps on opposite sides of vessel, coapt in middle
Unidirectional (prevent retrograde flow)
Valvular sinus – dilatation above valve (thrombosis site)
More numerous distally (discussed later)
Critical for venomotor pump (discussed later)
what are the 2 systems of the LE venous system and
how are they connected?
where do they drain?
deep venous and superfician venous.
connected by perforating veins
drains into central venous system (IVC, returns to rt atrium)
What % of the blood volume does the deep system carry?
where are these veins in relations to the arteries?
where are its “pairs”.
85% – embedded deep w/in muscles.
has adjacent arteries.
paired in the calf
What % of venous blook is carried by superficial arteries?
where are they located?
how does their blood flow?
10%
b/t subcutaneous tissues and muscle
from superficial to deep
what does the IVC bifurcate into?
rt/lt common ilias
lt common iliac
Posterior to rt common iliac artery at L5
May-Thurner Syndrome (iliac vein compression syndrome)
Pressurepoint(betweenrt CI artery and vertebral bodies) causes increased incidence of left LE venous thrombosis
what do the common iliacs bifurcate into?
inernal (hypogastric) and external iliac lower extremity
what does the external iliac become?
Common femoral at the:
Femoral v
inguinal ligament
Femoral triangel (Scarpa’s triangle)
Medial to CFA
Superficial circumflex is
Popliteal v
lateral and superior
ATV PER
Bifurcates 1.5-2 cm below inguinal ligament into
PTV
Profunda (Deep Fem)
Femoral (Superficial Fem)
what does the femoral beomce?
Popliteal at the Adductor
Femoral v
canal/hiatus (Hunter’s canal) posterior to knee
Popliteal v
Gastrocnemius (sural) veins paired, accompany sural artery, drain into popliteal
ATV PER
Gastronemius
Dumbellshaped sonographically
what does the popliteal branch into?
Calf veins are paired Duplicated
venae comitantes, corresponding veins
Anterior Tib – lateral
Posterior Tibial- Peroneal Trunk
Posterior Tibial- medial
Peroneal – middle of calf
where does the ant tib course?
lateral along interosseous membrane
where do teh post tib and peroneal receive blood from?
soleal veins (sinuses) of seleal and gastrocnemius muscles
what are tehe soleal sinuses?
reservoirs in soleal and gastro muscles tha tempty into PT and peroneal veins w/ muscle contraction. (spindles shaped channels)
after the tibial vines become metatarsal veins they connect to the dorsal veins to form ______?
deep plantar arch (dorsal arch)
what is this image?
transverse of calf, medial side up
what is this image?
calf veins in long
anatomical variants
Duplicated or bifid femoral vein and/or pop
Variations in popliteal region
esp trifurcation – no tibioperoneal trunk
Duplicated GS and/or LS
30% of population the LS joins somewhere other than popliteal (GS, Giacomini, SFV)
what do you see here?
bifed femoral vein common in 20% of the population
what variants are these?
variations of the popliteal fossa
where does teh greater saph vein join the deep system?
how much blood volume does it carry?
at the CFV 1.5-2 cm become the inguinal ligament.
~15%
often used for bypass
no adjacent arteries
often anomalous w/ double systems (8%) of non-continuous (25%)
where is the lesser saph located?
where is the typical confluence?
does it have an adjacent artery?
posterior aspect of calf b/t 2 heads of gatrocnemius muscles “stocking seam”; posterior to lateral malleolus
popliteal vein
no
where is the vein of giacomini?
what does it connect to?
thigh
connects to GS, popliteal or LS (aka intersaphenous vein)
where is the posterior arch vein?
what are it’s other names?
lateral calf
branch, accessory saph, posterior saph, sherman’s vein
where do the gastrocnemium muscles pump?
where do the soleal veins pump?
popliteal
post tim and peroneal veins
where do the peforator veins pass through?
how many valves in the perforators?
deep fascial plane
one valve, unidirectional
perforators in calf muscles
most perforators in medial calf
“Cockett’s”
GS to deep veins of calf which create the “GATOR ZONE”
perforators in the thigh
less in the knee and thigh.
called “boyd’s” at the knee from the GSV to pop
“dodd’s” in low thigh - GSV to SFV
hunterian - mid though
venous capacitance
70-80% blood volume
reservoirs for blood in emergency
what does occluding a vein do the blood volume?
increase blood volume (inflow capacitance)
what happens to blood volume when you release a vein from occlusion?
decreases in blood volume (outflow)
why are veins collapsible?]
how are they compressed?
poorly developed tunica media
can be compressed by positioning and tourniquets: extending leg, arm, flexing muscle, tourniquets or cuff will collapse extremity venous system
what is transmural pressure or resistance?
difference in pressure within veins (intraluminal) and pressure outside in tissue (interstitial)
how does transmural ressure determine the shape of a vein?
higher intraluminal = higher transmural = round, distended vein. Vice versa, then vein dumbbell-shaped.
what position is the patient to get this shape of vein?
1st = upright – hydrostatic pressure increases in LE, to approx. 102 mmHg. However, venous pressure remains low compared to arterial pressure because of venous compliance.
2nd = supine. hydrostatic pressure – distribution of blood, hydrostatic pressure 15 mmHg
what is this image showing us?
how hydrostatic pressure works.
what is capilllary bed perfusion deendent on?
a pressure gradient. low pressure in venules, high in arterioles
how much hydrostatic pressure is ther for every 12” of verticle drop (distal) below the heart?
22mmHg
what affects hydrosatic pressure?
gravity
what happens if you stand in place too long (due to hydrostatic pressure)?
increase transmural venous pressure distally
venous distention
venous pooling
decrease in capillary perfusion
decrease in venous return
decrease in cardiac output
resultin in HYPOTENSION!
what is edema?
excessive fluid in interstitial tissue, increased pressure.
When related to venous disease, due to increased capillary pressure from venous obstruction, which prevents fluid reabsorption and causes more fluid to move to interstitial space (pitting edema).
what is the purpose of venous valves and how many are there in each of these veins?
they prevent reversal of flow and there are 2 leaflets/valve
G. saphenous – 10-12 valves
L. saphenous – 6-12 valves
Soleal sinuses – none
Perforators – 1 each
Calf veins – 9-12 each
Popliteal and SFV – 1-3 each
CFV – 1
External iliac – usually 0, 25% have 1
Common iliac and internal iliac - 0
what is the “muscle pump”?
Blood must be pumped back toward the heart
Need to create higher pressure in venous system of the calf
Blood always flows from high pressure to low pressure
what happens when the calf muscle contracts?
causes venous blood to squeeze out of venous sinusoid in tissue, into deep veins of calf and into thigh, etc.
Contraction also moves blood from calf to thigh and beyond
Valves superior to muscles open
Valves inferior close
what happens during muscle relaxation?
Relaxation allows sinuses to refill in muscles
During this phase blood flows inferiorly in the deep veins momentarily to close the valves
Relaxation allow blood to flow from superficial veins to deep veins through perforating veins (communicating)
what is the difference in hydrostatic venous pressure when a person is walking, laying down or standing still?
standing 80mmHg
lying 10 mmHg
walking 25mmHg
what is reqired for the calf veno-motor pump to be effective?
what does an effective pump do?
semilunar valves are abundant in calf
abundant veins in calf: PTV’s, Peroneals, ATV’s, Gastrocs, Soleal sinuses, Greater & Lesser Saphenous, Perforators
abundant skeletal muscles that contract
it…Facilitates venous return to heart
Reduces the effect of hydrostatic pressure
& Reduces venous pooling
why does respiration change venous flow?
b/c of the change in abdominal pressure during respiration
what happens during inspiration to the venous system?
Diaphragm moves inferiorly
Increases intraabdominal pressure.
Pressure gradient between LE vein and intraabdominal veins decreases
LE flow decreases.
what happens to the venous system during expiration?
Diaphragm moves superiorly
Decreases intraabdominal pressure
Increasing pressure gradient between abdomen and LE veins
Flow from LE increases
what does valsalva do to pressure?
what patients should not practice this maneuver?
increases intrathoracic pressure, stopping venous return.
Flow augmentation when valsalva released.
Do not perform on patients with CAD, acute MI, moderate/severe hypovolemia.
