lower extremity venous anatomy

Question 1

what are the 3 layers of the venous wall?

Answer 1

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

Question 2

describe the venous valves

Answer 2

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)

Question 3

what are the 2 systems of the LE venous system and

how are they connected?

where do they drain?

Answer 3

deep venous and superfician venous.

connected by perforating veins

drains into central venous system (IVC, returns to rt atrium)

Question 4

What % of the blood volume does the deep system carry?

where are these veins in relations to the arteries?

where are its “pairs”.

Answer 4

85% – embedded deep w/in muscles.

has adjacent arteries.

paired in the calf

Question 5

What % of venous blook is carried by superficial arteries?

where are they located?

how does their blood flow?

Answer 5

10%

b/t subcutaneous tissues and muscle

from superficial to deep

Question 6

what does the IVC bifurcate into?

Answer 6

rt/lt common ilias

Question 7

lt common iliac

Answer 7

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

Question 8

what do the common iliacs bifurcate into?

Answer 8

inernal (hypogastric) and external iliac lower extremity

Question 9

what does the external iliac become?

Answer 9

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)

Question 10

what does the femoral beomce?

Answer 10

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

Question 11

what does the popliteal branch into?

Answer 11

Calf veins are paired  Duplicated
 venae comitantes, corresponding veins

 Anterior Tib – lateral

 Posterior Tibial- Peroneal Trunk
 Posterior Tibial- medial

 Peroneal – middle of calf

Question 12

where does the ant tib course?

Answer 12

lateral along interosseous membrane

Question 13

where do teh post tib and peroneal receive blood from?

Answer 13

soleal veins (sinuses) of seleal and gastrocnemius muscles

Question 14

what are tehe soleal sinuses?

Answer 14

reservoirs in soleal and gastro muscles tha tempty into PT and peroneal veins w/ muscle contraction. (spindles shaped channels)

Question 15

after the tibial vines become metatarsal veins they connect to the dorsal veins to form ______?

Answer 15

deep plantar arch (dorsal arch)

Question 16

what is this image?

Answer 16

transverse of calf, medial side up

Question 17

what is this image?

Answer 17

calf veins in long

Question 18

anatomical variants

Answer 18

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)

Question 19

what do you see here?

Answer 19

bifed femoral vein common in 20% of the population

Question 20

what variants are these?

Answer 20

variations of the popliteal fossa

Question 21

where does teh greater saph vein join the deep system?

how much blood volume does it carry?

Answer 21

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%)

Question 22

where is the lesser saph located?

where is the typical confluence?

does it have an adjacent artery?

Answer 22

posterior aspect of calf b/t 2 heads of gatrocnemius muscles “stocking seam”; posterior to lateral malleolus

popliteal vein

no

Question 23

where is the vein of giacomini?

what does it connect to?

Answer 23

thigh

connects to GS, popliteal or LS (aka intersaphenous vein)

Question 24

where is the posterior arch vein?

what are it’s other names?

Answer 24

lateral calf

branch, accessory saph, posterior saph, sherman’s vein

Question 25

where do the gastrocnemium muscles pump? where do the soleal veins pump?

Answer 25

popliteal post tim and peroneal veins

Question 26

where do the peforator veins pass through? how many valves in the perforators?

Answer 26

deep fascial plane one valve, unidirectional

Question 27

perforators in calf muscles

Answer 27

most perforators in medial calf "Cockett's" GS to deep veins of calf which create the "GATOR ZONE"

Question 28

perforators in the thigh

Answer 28

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

Question 29

venous capacitance

Answer 29

70-80% blood volume reservoirs for blood in emergency

Question 30

what does occluding a vein do the blood volume?

Answer 30

increase blood volume (inflow capacitance)

Question 31

what happens to blood volume when you release a vein from occlusion?

Answer 31

decreases in blood volume (outflow)

Question 32

why are veins collapsible?] how are they compressed?

Answer 32

poorly developed tunica media can be compressed by positioning and tourniquets: extending leg, arm, flexing muscle, tourniquets or cuff will collapse extremity venous system

Question 33

what is transmural pressure or resistance?

Answer 33

difference in pressure within veins (intraluminal) and pressure outside in tissue (interstitial)

Question 34

how does transmural ressure determine the shape of a vein?

Answer 34

higher intraluminal = higher transmural = round, distended vein. Vice versa, then vein dumbbell-shaped.

Question 35

what position is the patient to get this shape of vein?

Answer 35

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

Question 36

what is this image showing us?

Answer 36

how hydrostatic pressure works.

Question 37

what is capilllary bed perfusion deendent on?

Answer 37

a pressure gradient. low pressure in venules, high in arterioles

Question 38

how much hydrostatic pressure is ther for every 12" of verticle drop (distal) below the heart?

Answer 38

22mmHg

Question 39

what affects hydrosatic pressure?

Answer 39

gravity

Question 40

what happens if you stand in place too long (due to hydrostatic pressure)?

Answer 40

increase transmural venous pressure distally venous distention venous pooling decrease in capillary perfusion decrease in venous return decrease in cardiac output resultin in HYPOTENSION!

Question 41

what is edema?

Answer 41

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).

Question 42

what is the purpose of venous valves and how many are there in each of these veins?

Answer 42

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

Question 43

what is the "muscle pump"?

Answer 43

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

Question 44

what happens when the calf muscle contracts?

Answer 44

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

Question 45

what happens during muscle relaxation?

Answer 45

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)

Question 46

what is the difference in hydrostatic venous pressure when a person is walking, laying down or standing still?

Answer 46

standing 80mmHg lying 10 mmHg walking 25mmHg

Question 47

what is reqired for the calf veno-motor pump to be effective? what does an effective pump do?

Answer 47

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

Question 48

why does respiration change venous flow?

Answer 48

b/c of the change in abdominal pressure during respiration

Question 49

what happens during inspiration to the venous system?

Answer 49

Diaphragm moves inferiorly Increases intraabdominal pressure. Pressure gradient between LE vein and intraabdominal veins decreases LE flow decreases.

Question 50

what happens to the venous system during expiration?

Answer 50

Diaphragm moves superiorly Decreases intraabdominal pressure Increasing pressure gradient between abdomen and LE veins Flow from LE increases

Question 51

what does valsalva do to pressure? what patients should not practice this maneuver?

Answer 51

increases intrathoracic pressure, stopping venous return. Flow augmentation when valsalva released. Do not perform on patients with CAD, acute MI, moderate/severe hypovolemia.