Vascular Rehabilitation Subin Solomen, Pravin Aaron
Page numbers followed by f refer to figure and t refer to table
Ablative therapy 72
Acne 207
keloid 207
Acrocyanotic syndromes 141
embolism 61
plethysmography 71, 92, 95
Ambulatory venous pressure 71, 96
Amniotic fluid embolism 62
Aneurysm 37, 149
Aneurysmal sac 41
wrapping of 41
Aneurysmorrhaphy 41
Angiogenesis 166, 168, 173
Angiogram 40
Angioplasty 36, 149, 151
Angiotensin-converting enzyme inhibitors 36
brachial index 90, 91, 92t, 112f, 116, 186
circumference 96
dorsiflexion 112f
plantar flexion 112f
Antibiotics 50, 53
Anticancer drugs 171
Anticoagulant 65, 171
therapy 53, 123
Antiplatelet medications 36
Antiseptics 174
Antithromboembolic stockings 140, 141
Antyllus method 41
Aortography 40
Aplasia 75
bypass 50
disease 171
obstructive 141
disorders 29, 103, 104, 106, 107
acute 110
chronic 111
classification of 27
embolism 40
grafts 149, 151
insufficiency 101, 164
ligation 41
occlusion, acute 110
studies 90
surgeries 149, 160
system 3
ulcer 177, 181, 205, 206
Arteriography 93
Arterioles 1, 11
Arteriolitis, necrotizing 29, 30
Arteriosclerosis 29, 149
hyperplastic 30
hypertensive 29
Arteriovenous malformation, congenital 40
Artery 1, 4f, 44f, 83, 149
calcium, coronary 35
capillary-vein system 4f
disease, coronary 21, 104
inflammation of 32
popliteal 34
Atherogenesis 33
Atherosclerosis 29, 30, 32, 33, 49, 149
theories of 33
Atherosclerotic aneurysms 38
Atrial congestion 143
Atrophic blanching 70
Auscultation 63, 87
Axillary vein 5
Baker's cyst 141
Bandaging techniques 138
Basal cell carcinoma 165
Basilic vein 4
Bates-Jensen wound assessment tool 109
Bazin's ulcer 177
Benzopyrones 79
Berry aneurysm 38
Beta blocker medications 36
Blood 40
circulation 171
clot 32
flow 14
velocity of 12
pressure 87
systemic 62, 63
test 64
transportation of 10
vessels 1, 19
palpation of 84
Blunt trauma 163
Bone marrow 8
Brachial veins 4
Brasdor's method 41
Brawny edema 77
Buerger's disease 24, 47, 48, 48f, 49, 50, 181
Buerger's exercise 112f, 113
Butterfly keloid 207
Calcinosis cutis 49
Calcium channel blockers 36, 46
Cardiovascular system 10
Carotid aneurysm, symptoms of 39
Cavernous hemangiomas 153
Cellulitis 128
Central aneurysms 38
Cerebrovascular accident 40, 159
Cervical sympathectomy 150
Charcot foot 165
Charles’ operation 80, 158
Chemical sympathectomy 150
Circle of Willis 3, 38
Circulation, classification of 10
Circulatory system 2
components of 1
Claudication 28, 82, 103
distance, functional 104
intermittent 48, 82, 82t
mild 27
moderate 27
scale 107
severe 27
test 88
venous 69
injury 177
laser therapy 203
stimulation test 45
deposition 168
injections 209
Combined physical decongestive therapy 128
Complex lymphedema therapy 129
Compression 122, 128, 129, 135
therapy 134, 141, 204, 205
intermittent 114
timing of 143
Computed tomography 35, 40, 101
Connective tissue
disorders 171
massage 113
Constipation 57
Continuous short wave diathermy 202
Contraception 54
Contraction 170
Contralateral limb, reflex heating of 113
Cosmetic deformity 209
Costophrenic angles, blunting of 64
Cough 39, 63
Crest syndrome 49
Critical limb ischemia 21, 28
Cryoplasty 36
Decongestive lymphatic therapy 129
Decubitus ulcer 165, 188
Deep breathing exercises 130
Deep vein 7
damage 59f
thrombosis 53, 82, 88, 102, 103, 159
Deformity, functional 209
Dermal matrix 166
Dermatitis 143
Diabetes mellitus 22, 31, 165
foot 26, 185
disease 26
syndrome 26
footwear 187
ulcer, grading of 185
Diethylcarbamazine 79
Digital contrast angiography 93
Diuretics 79
Doppler velocimetry 93
Dorsal venous network 4
Drainage, types of 196
Duplex venous ultrasonography 55
Echocardiography 49, 64
Edema 69, 86f, 96, 123, 127, 171, 196
cardiac 145, 147
palpation of 85
post-traumatic 141
tester 97, 97f
modified 98f
Electrical stimulation 199, 200
Electrocardiogram 115
Electroionizing radiation therapy 204
Embolectomy 149
pulmonary 65
Endarterectomy 36, 149
Endothelial cells 166
Endothelium 3
vascular 29
Endovascular therapy 72
Epidermal growth factor 33
Epithelialization 169, 194
Erythema 54
Excision 41, 42, 209
Exercise 129, 130, 205
flexibility 131
foot 122, 161
guidelines 115
limitation 66
physiologist 125
testing 115
External pneumatic compression 56
Extracellular matrix 168
Fahraeus-Lindqvist effect 20
Fat embolism 61
Fibroblast 166
growth factor 33
Fibromyalgia, rheumatic 141
Fibroplasia 168
Figure of eight
bandaging 139
method 85, 97
Fleischner sign 64
Fluorescence microlymphangiography 100
Folliculitis 207
Foot pressure assessment 187
Fractures 53
Gait assessment 87
Gangrene 27
Gentle stretching exercises 113
Graft obstruction, sign of 159
Granulation tissue 168, 194
Great saphenous vein 6, 6f
Hampton hump 64
Head and neck, congestion of 40
Headache 39, 40
Healing 176
Heart 11, 14
disease, ischemic 32, 40
failure 141
congestive 40, 53
function 62
dissipation 10
therapy 128
Hemangiopathy, lymphostatic 80
Hematoma 157
Hemolytic uremic syndrome 30
Hemoptysis 63
Hemorrhage 159
cerebral 40
Hemosiderin degradation 154
Hemothorax 40
Homan's reducing operation 158
Human leukocyte antigen 47
Hunter's method 41
Hyaline arteriosclerosis 29
Hydrocortisone 208
Hyperbaric oxygen therapy 183
Hyperlipidemia 31
Hyperpigmentation 69, 70
Hyperplasia 75
Hypertension 31
malignant 30
venous 171
Hypertrophic scar 207, 208, 208t
Hyperventilation, alveolar 62
Hypoplasia 75
Hypotension 63
systemic 62
insudation 32
monoclonal 34
Hypoxia 171
Hysteresis 135
Infection 75, 159, 171, 184, 185
Inferior vena cava occlusion 65
Inflammation 75, 154, 171
Injury hypothesis 33
International Society of Lymphology lymphedema staging 79t
Intestinal obstruction 40
Ionozone therapy 203
Iontophoresis 113, 201
Irritation 171
Ischemia 27, 171, 143, 184, 185
intestinal 40
signs of 84
Jugular venous engorgement 63
scar 207, 208, 208t
types of 207
Knuckle sign 64
Kontoleon's operation 158
Laminar flow 17, 17f
Laplace law 13, 135
Large pulmonary embolism 62
Laser therapy 60
condition of 177
exercises 122
muscles 7
ulcer 108
chronic 26
measurement tool 108
volume 98
Light reflection rheography 95
cellulites of 143
lymphedema of 141
Lipodermatosclerosis 69
Liposuction 79, 80, 157, 158
Lower extremity pain 82t
Lower limb
lymphedema 134
training 126
Lumbar sympathectomy 50, 150
Lymph 8
capillaries 9
nodes 8, 9
organs 8
vessels 8, 9, 75
Lymphangiogram 99
bypass procedures 79, 80, 157, 158
drainage 129
exercises 132, 133
duct 9
surgeries 157
ulcers 205
vessels 8
Lymphedema 74, 99, 102, 127, 165
chronic 78f
congenital 75
development of 75, 76t
praecox 75
prevention of 147
primary 74
secondary 74
tarda 75
Lymphography scanning procedures 75
Lymphoid tissue 8
Lymphoscintigram 100
Magnetic resonance
angiography 50
imaging 41, 55, 101
Malignant disease 145, 147
Manual lymphatic drainage 129, 144
Marfan's syndrome 38, 171
Martorell's ulcer 177
Matrix metalloproteinase 170
Mature scar 207
May-Thurner syndrome 67
McConnell's sign 64
Melanoma 165
Microcurrent electrical neuromuscular stimulator 201
Microvascular tissue compartment 137
Migraine 40
Migratory superficial vein thrombophlebitis 48
Mold method 198
Monckeberg arteriosclerosis 29, 30
Monoclonal theory 33
Motor sensory status 85
Muscle contraction 6
Mycotic aneurysm 38
Myocardial infarction 40, 53
Myofibroblasts 166
Nausea 39
Neck vein distention 63
Necrosis 27, 171, 193
Negative pressure wound therapy 206
Neoplasm 40, 53, 165
Neuropathy 165, 184
Nonthrombotic pulmonary embolism 61
Nottingham health profile 106
Obesity 32, 171
Obliterating telangiectasias 153
Ohm's law 13, 14t
Olin's diagnostic criteria 49
Omega-3 polyunsaturated fatty acid 36
Optoelectronic volumetry 99
Oral contraceptives 32
Ornamental keloid 207
Osteoarthropathy, neuropathic 165
Osteoarticular disorders 141
deprivation 66
therapy 66
Pain 28, 40, 82, 154, 157, 173, 177, 194
relief of 122, 125
Pallor 28
Palpable cord 54
Paralysis 28
Paresthesias 28, 48, 83
Pedal ischemia 27
Peripheral arterial
disease 35, 104, 107, 115
disorders 114, 115
Peripheral neuropathy 159
Peripheral vascular
disease 21, 27, 81, 88, 103, 121, 173
disorders 21, 87
Peri-wound skin 196
Perthes test 90
Pharmacological therapy 72
Phlebectomy 154
venous 73
Phlebitis 60
superficial 83
Phlebography 53, 71, 95
Phlegmasia alba dolens 54
Phonoangiography 50
Photographic wound assessment tool 108
Photoplethysmography 70, 94
Physiotherapy 110, 161, 162
hydrostatic pressure 77
osmotic pressure 77
Plethysmography 50
Pleural friction rub 64
Pneumatic compression
therapy 206
treatment 141
Pneumothorax 40
Pole test 92
Postcapillary venules 11
Post-exercise ankle brachial index 92
Pregnancy 54, 56
toxemia of 30
Pressure 12, 13
prevention of 190
status tool 108
ulcer 165
scale 109
Promote granulation tissue formation 173
Prophylaxis 55
Pulsed electromagnetic energy 202
Pump technique 144
Radiofrequency, endovenous 72
Ratschow's exercise 114
Raynaud's disease 42, 49, 149, 181
Raynaud's phenomenon 48, 49, 141
pathophysiology of 44
Reflux 69
Resting ankle brachial index 91
Resuscitation 65
Rokitansky, thrombogenic theory of 33
Rotary technique 144
Saphenous vein 6, 6f
endovenous obliteration of 60
Scar 207
management of 209
remodeling of 200
unstable 207
Sclerodactly 49
Scleroderma 30, 49
Sclerosing agents 154
Sclerotherapy 60, 72, 152, 155t, 157, 162
failure of 157
Scoop technique 144
Segmental scar reduction 209
Seizures 39
Semmes-Weinstein monofilaments 85
Septic pulmonary emboli 61
Serum protein electrophoresis 45
Simple lymphatic drainage 145, 146
Sistrunk's reducing operation 80, 158
Six minute walk test distance 105
assessment 118
care 72, 114, 130, 148
condition of 177
hygiene 50, 129
hyperkeratotic 120
infections 127
moisturizing 119
scaly 120
temperature 84, 187
tension 208
chloride, hypertonic solution of 154
iodide 154
tetradecyl sulfate 154
Soft tissue techniques 199
Sores 48
Spider vein 59f, 153
Spinal cord stimulation 183
Spleen 8
Splints 212
Starling's law 19
Stasis dermatitis 70
Stemmer's sign 90f
Stemmer's test 90
Steroid 171
injection 208
topical 171
Stroke 53
Superficial vein 54
thrombosis 52
Supplemental oxygen therapy 65
Surgeries, types of 149
Surgical scar 207
Sweating 63
Swelling 48
Sympathectomy 149
Syncope 63
Syphilitic aneurysm 38
Systolic blood pressure 116
Tachycardia 39
Tachypnea 39, 63
Telangiectasia 49, 69
Tension 13, 135, 171
Thompson's buried dermis flap operation 80, 158
Thoracic venous occlusion 143
Thromboangiitis obliterans 47, 52, 149
Thrombocytopenia, heparin-induced 55
Thromboembolism, venous 24
Thrombolytic therapy 50, 65
Thrombophlebitis 53, 143
Thrombosis 149, 154, 157
coronary 159
venous 108
Thrombus, venous 138
Thymus 8
Toe systolic pressure index 92
Tonsils 8
Tracing film method 197, 198
electrical nerve stimulation 188
oxygen tension 182
Transfascial perforating veins 153
Trauma 53, 75, 149
types of 207
Treadmill testing 104
Tremors 39
Triamcinolone 208
Tropic scar 207
Tumor 40
emboli 61
Tunica adventitia 1
Tunica intima 3
Tunica media 3
Turbulent flow 18
Ulcer 69, 178, 178f, 196f, 198
chilblains 177
chronic 164
cryopathic 177
diabetic 177, 184
erythrocyanoid 177
gastrointestinal 40
hypertensive 177
management 187
mixed 204
nonhealing 27
prevention of 183, 188
venous 60, 108, 177, 177t, 178, 206
Ultrasound 35, 100, 202
scanning 40
Ultraviolet radiation 202
Unilateral leg swelling 54
Upper limb
lymphedema 133
training 126
Uremia 171
Urine analysis 40
Uterus pressing pelvic veins 57f
Vacuum assisted closure 206
Valves 7, 8
development of 56
failure 58f
reconstruction 73
Vancouver scar scale 109
Varicogram 58
Varicose vein 56, 58f, 59f, 69, 108, 123, 153, 154
diseases 121
disorders 101, 110
rehabilitation 125
program 126t
Vasodilators 46, 50
Veins 4, 4f, 11, 141
functions of 7
ligation of 180, 181
rupture of 60
stripping of 154, 162
transplant 73
Vena cava 11, 55
Venography 55, 71
Venous disorders 24, 52, 106, 107
acute 122
chronic 24, 123
Venous severity score 103
Venous thrombosis, prevention of 122
Venous ulcer recurrence, prevention of 181
Virchow, lipid theory of 33
Wagner-Meggitt grading 185t
Wardrop's method 41
Westermark's sign 64
Windkessel vessels 19
Wound 163, 198
acute 163, 164
assessment 192
care 72
chronic 164
classifications 163
closed 164
depth of 208
duration of 194
healing 165, 166, 171, 172
infection 50, 157
management 114, 163, 173
measurement 197
open 163
photography 197
stages of 196, 196t
tidy 164
tracing method 108
types of 194
untidy 164
Chapter Notes

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Anatomy of Blood Vessels1

Blood and lymph flows through circulatory system and lymphatic system respectively. The circulatory system consists of the heart and blood vessels through which the blood circulates.
The lymphatic system consists of lymph nodes, lymph organs and lymph vessels, through which colorless lymph flows. It consists of central and peripheral lymphoid system. Central lymphoid system includes thymus and bone marrow and peripheral includes lymph nodes, spleen, lymph vessels, etc.
  • Systemic circulation (Fig. 1.1): The blood pumped out from the left ventricle is carried by the branches of the aorta around the body and is returned to the right atrium of the heart by the superior and inferior vena cava.
  • Pulmonary circulation: This consists of the circulation of blood from the right ventricle of the heart to the lungs and back to the left atrium. In the lungs, carbon dioxide is excreted and oxygen is absorbed.
  • Coronary circulation: The blood is circulated through coronary arteries, which is a branch of ascending arteries and supplies the heart itself and returned to right atrium. Compare to other circulation heart receives its blood supply during diastole.
The heart pumps blood into vessels that vary in structure, size and function, and there are several types of blood vessels—arteries, arterioles, capillaries, venules and veins (Table 1.1).
Arteries and Arterioles
Arteries and arterioles are the blood vessels that transport blood away from the heart. They vary considerably in size and their walls consist of three layers of tissue:
  • Tunica adventitia or outer layer of fibrous tissue2
    zoom view
    Flow chart 1.1: Circulatory system
    zoom view
    Fig. 1.1: Systemic circulation
    Table 1.1   Pathway of blood from periphery to the heart
    Blood vessel
    Exchange of substance between blood and tissue fluid
    Connects capillary bed to venules
    Superficial vein
    Primary collecting veins in extremity
    Perforating vein
    Connect superficial veins to the deep veins
    Deep veins
    Carry blood from perforating and superficial veins to vena cava
    Vena cava
    Carries blood from periphery to right atrium of heart
    (Reprinted with permission)
  • Tunica media or middle layer of smooth muscle and elastic tissue
  • Tunica intima or inner lining of squamous epithelium called endothelium
Arterial walls are thicker because of more smooth muscles compared to veins. In the large arteries, elastic arteries, the tunica media consists of more elastic tissue and less smooth muscle. In the arteries, the tunica media consists almost entirely of smooth muscle (Fig. 1.2).
Anastomoses and End-arteries
Anastomoses are arteries that form a link between main arteries supplying an area, e.g. the arterial supply to the palms of the hand and soles of the feet, the brain, joints and to a limited extent, the heart muscle. When there is a block in the arteries, these arteries ensures the circulation is bypassed through a collateral circulation. End-arteries are the arteries with no anastomoses or those beyond the most distal anastomoses, e.g. the branches from the circulus arteriosus (circle of Willis) in the brain or the central artery to the retina of the eye. When an end-artery is occluded the tissues it supplies die because there is no alternative blood supply.
The smallest arterioles break up into a number of minute vessels called capillaries. Blood cells and large-molecule substances such as plasma proteins do not normally pass through capillary walls. The capillaries form a vast network of tiny vessels, which link the smallest arterioles to the smallest venules (Fig. 1.3). The capillary bed is the site of exchange of substances between the blood and the tissue fluid, which bathes the body cells.
Venules connect the capillaries (arterial system) to the venous system. Venules are very small in diameter and oval-shaped at rest. When pressures increase, they become more circular. While blood vessels typically have three distinct layers, the end venules have only an endothelial layer with a thin layer of collagen fibers (tunica intima).4
zoom view
Fig. 1.2: Histology of artery and vein
zoom view
Fig. 1.3: The artery-capillary-vein system
As venules increase in diameter and become visible veins, they have the typical three layers mentioned earlier. Veins in the upper extremities and lower extremities are superficial and deep. The two superficial vein extremities are of upper extremities are cephalic and basilic vein. The deep veins are named corresponding to the accompanying arteries or arterial system at the similar level of the vascular system. The basilic vein originates from the dorsal venous network of the hand. It ascends the medial aspect of the upper limb. At the border of the teres major, the vein moves deep into the arm. Here, it combines with the brachial veins to form the axillary vein. The cephalic vein arises from the dorsal venous network of the hand. It ascends the anterolateral aspect of the upper limb, passing anteriorly at the elbow. At the shoulder, the cephalic vein5 travels in the deltopectoral groove and enters the axilla. Within the axilla, the cephalic vein terminates by joining the axillary vein. In cubital fossa, they are connected by median cubital vein, which is common site of intravenous (IV) injection. Another site for IV is dorsal venous arch of hand. Median cubital vein is commonly affected with superficial thrombophlebitis and dorsal venous arch is a common site for cellulitis.
There are three different types of lower extremity veins, which are superficial, perforating, and deep veins. The superficial veins conduct blood from the skin and subcutaneous tissue. The perforating veins connect the superficial veins to the deep veins that convey blood from the periphery to the heart. One anatomical structure the perforating, superficial and deep veins have in common is valves. The superficial veins have fewer valves than the deeper veins. Vein valves are bicuspid and avascular. They consist of thin sheets of collagen and smooth muscle with an endothelial covering. Valves appear to become less flexible as people age. The valves prevent retrograde blood flow, thus allowing veins to overcome gravity effects (Figs 1.4A and B).
The main, superficial leg veins include the greater saphenous, lesser saphenous, and the lateral (subdermis) venous system. Descriptions of saphenous veins are listed in Table 1.2 and their difference is given in Table 1.3. These veins are very thin walled and distensible. The superficial veins lie above the main fascia plane and are the primary blood collection system for the lower leg. They lack the extensive fascial restriction experienced by the deep veins. Consequently, superficial veins may undergo dramatic volume changes or distention. The lateral venous system (lateral subdermic) above/below the knee is a common area for varicosities during pregnancy and occasionally puberty.
zoom view
Figs 1.4A and B: (A) Valve in a closed position which prevents retrograde flow; (B) Valve in open position which allows proximal flow
Table 1.2   Main superficial veins of lower extremity
Anatomical locations
Great saphenous vein
Starts at medial foot, above malleolus; goes to anterior, medial calf, knee, medial thigh. Ends at common femoral vein
Often site of varicose veins in lower thigh and upper calf
Lesser or short saphenous vein
Starts at lateral foot and posterior/lateral malleolus, goes up posterior/lateral or Short) leg below knee, between gastrocnemius heads into popliteal fossa. Connects (lateral calf, lower 1/3 of leg behind the lateral malleolus)
Reflux usually where this vein and tributaries are superficial to fascia
Lateral venous (sub dermic system)
On lateral aspect of leg; above and below the knee
Common area for isolated spider veins in young women
(Reprinted with permission)
Table 1.3   Description of great saphenous and small saphenous vein
Great saphenous vein
Small saphenous vein
Long saphenous vein
Short saphenous vein
By joining medial end of dorsal venous arch and dorsal vein of great toe
By joining lateral end of dorsal venous arch and dorsal vein of little toe
At ankle
Anterior to medial malleolus
Anterior (tibial border)
Behind knee
Medial side of the thigh
Posterior to lateral malleolus
Posterior (along the border of tendo-achilles)
To femoral vein in femoral triangle
To popliteal vein in popliteal fossa
Table 1.4   Perforating veins of lower extremity
Mid to upper medial thigh
Proximal, medial knee, distal medial thigh
Lower medial calf
Posterior medial ankle; posterior arch of foot
(Reprinted with permission)
The superficial veins deliver blood to the deep veins, such as the femoral and popliteal veins. However, the superficial system also connects to perforating veins.
The perforating veins penetrate fascia and connect the superficial venous system to the deep veins (Table 1.4). Muscle contraction produce pressure that assists blood movement from perforators into the deep veins (muscle pump). Perforating veins have valves, which prevent retrograde blood flow, i.e. back to superficial. The lower leg and foot have more perforating veins than the upper leg.7
In the legs, deep veins often run parallel to superficial veins. The perforating veins connect superficial veins to deep veins like slanted rungs of a ladder. The deep veins are named corresponding to the accompanying arteries or arterial system at the similar level of the vascular system.
Functions of Vein
  • To carry blood to the heart/lungs for gas, nutrient and waste exchange.
  • Storage of large blood volume.
  • Veins are barriers between intravascular and extravascular tissues. The proximal venules allow movement of interstitial fluids, large molecules and white blood cells through the venule wall.
  • Vein walls also have cellular functions. White blood cells attach to vein endothelium in order to be available should there be an injury or disease process.
  • Veins also are a factor in cardiovascular pressures. In the capillary bed, veins influence arterial output resistance. Vein walls produce nitric oxide that causes vasodilation via decreased vascular tone.
  • Veins also have a role in heart filling pressure. The skeletal muscle pump, venous myogenic response and venous smooth muscle tone prevent orthostatic hypotension.
  • The venules also appear to be a site of angiogenesis.
  • Venous endothelium has a role in lessening platelet aggregation to prevent clot development via the formation of prostacyclin.
  • Other unique or regional functions:
    • Facial veins allow for blushing and temperature regulation of the head.
    • Cutaneous veins help regulate body/skin temperature.
    • The internal jugular vein facilitates cranial pressure regulation.
    • Proximal portion of the vena cava and pulmonary veins may play a role in cardiac pacing. Their tunica media layers have cardiac myocytes that might provide cardiac pacing during some pathological conditions.
Mechanism, Which Helps in Back Flow of Blood from the Legs to the Heart
  • Pressure from behind: The slight pressure pushing blood onwards from the capillaries into the venules. Although this is sufficient when we lie down, it is totally inadequate when we are standing or walking.
  • Suction effect of the lungs: When we take a deep breath a negative pressure, rather similar to a vacuum, is created in the chest that helps to draw blood upwards to the heart.
  • Pumping action of the leg muscles: These muscles are enclosed in a dense sheath of fibrous tissue (called the deep fascia). When you walk about, the muscles contract and the veins contained in the fibrous sheath are squeezed.
  • Valves in the deep vein: At intervals along the insides of the veins are beautifully constructed valves, consisting of two flaps that meet each other exactly. Though very simple they are quite sufficient nevertheless to8 make sure that the blood can be squeezed in one direction only back to the heart.
  • Valves in the perforating vein: The veins that drain these superficial tissues are linked up with the deep veins through a number of perforations in the fibrous sheath. Each linking or communication vein is guarded by a one-way valve. As we walk, the muscle pump squeezes the deep veins in our legs; blood is pushed upwards towards the heart; and the negative pressure within the deep veins sucks in blood through the communicating veins from the skin and the fat.
  • Controlled venous diameter, high pressure on the arterial side, and the low right atrium pressure that draws blood from the great veins.
In the interstitial space, majority of the tissue fluid drains to their venous end whereas the remainder diffuses through permeable walls of the lymph capillaries and becomes lymph. Lymph is a clear watery fluid, similar in composition to blood plasma, with the important exception of plasma proteins and identical in composition to interstitial fluid.
The lymphatic system consists of:
  • Lymph
  • Lymph vessels
  • Lymph nodes
  • Lymph organs, e.g. spleen and thymus
  • Diffuse lymphoid tissue, e.g. tonsils
  • Bone marrow.
The lymphatic system function are to drain tissue fluid, plasma proteins and other cellular debris back into the bloodstream, and is also involved in immune defense. Fat and fat-soluble materials, e.g. the fat-soluble vitamins, are absorbed into the central lacteals (lymphatic vessels) of the villi.
zoom view
Fig. 1.5: Lymphatic circulation
Lymph Capillaries
Lymph capillaries originate as blind-end tubes in the interstitial spaces. They have the same structure as blood capillaries, i.e. a single layer of endothelial cells, but their walls are more permeable to all interstitial fluid constituents, including proteins and cell debris. The tiny capillaries join up to form larger lymph vessels.
Larger Lymph Vessels
The walls of lymph vessels are about the same thickness as those of small veins and have the same layers of tissue, i.e. a fibrous covering, a middle layer of smooth muscle and elastic tissue and an inner lining of endothelium. Lymph vessels have numerous cup-shaped valves, which ensure that lymph flows in one way only, i.e. towards the thorax. There is no ‘pump’, such as the heart, involved in the onward movement of lymph, but the muscle tissue in the walls of the large lymph vessels has an intrinsic ability to contract rhythmically (the lymphatic pump). In addition, any structure that periodically compresses the lymphatic vessels can assist in the movement of lymph along the vessels, commonly including the contraction of adjacent muscles and the pulsation of large arteries. Lymph vessels are divided into superficial and deep lymphatic vessels. Lymph vessels become larger as they join together, eventually forming two large ducts, the thoracic duct and right lymphatic duct, that empty lymph into the subclavian veins.
Thoracic Duct
Thoracic duct begins at the cisterna chyli, which is a dilated lymph channel situated in front of the bodies of the first two lumbar vertebrae. The duct is about 40 cm long and opens into the left subclavian vein in the root of the neck. It drains lymph from legs, the pelvic and abdominal cavities, the left half of the thorax, head and neck, and the left arm.
Right Lymphatic Duct
Right lymphatic duct is a dilated lymph vessel about 1 cm long. It lies in the root of the neck and opens into the right subclavian vein. It drains lymph from the right half of the thorax, head and neck and the right arm.
Lymph Nodes
Lymph nodes are oval or bean-shaped organs that lie, often in groups, along the length of lymph vessels. The lymph drains through a number of nodes, usually 8–10 nodes, before returning to the venous circulation. Function of lymph nodes includes filtering, phagocytosis and proliferation of lymphocytes.