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Even under normal circumstances, slightly more fl uid is fi ltered out of the capillaries into

the interstitial fl uid than is reabsorbed from the interstitial fl uid back into the plasma. On

average, the net fi ltration pressure starts at 11 mm Hg at the beginning of the capillary,

Lymphatics

whereas the net reabsorption pressure only reaches 9 mm Hg by the vessel’s end. Because of this pressure differential more

fl uid is fi ltered out of the fi rst half of the capillary than is reabsorbed in its last half. If this extra fi ltered fl uid were not drained

away, the consequence of this unbalanced exchange would be accumulation of excess interstitial fl uid, or edema. To circumvent this potentially disastrous problem, a system of accessory drainage vessels, the lymphatic vessels, evolved in vertebrate

animals. This lymphatic system of vessels consists of an extensive network of one-way tubes that provide an accessory route

through which fl uid is returned from the interstitial fl uid to the blood to keep the cardiac output and return equal.

Dissection of lymphatic vessels and nodes in the thigh

Anterior view

 1 Superficial inguinal lymph node

 2 Afferent lymphatic vessels

 3 Efferent lymphatic vessels

 4 Great saphenous vein

 5 Femoral vein

 6 Femoral artery

 7 Spermatic cord

 8 Penis

 9 Sartorius muscle

10 Rectus femoris muscle

 11 Femoral nerve

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REAL ANATOMY

Th e respiratory system consists of a

network of passageways that begin at the openings into the nose and mouth

and terminate in about 600 million microscopic air spaces within the substance

of the lungs. Th e passageways are typically divided into upper respiratory passageways and lower respiratory passageways. Th e upper respiratory tract consists

of the nose, the nasal cavity and associatied sinuses, and the pharynx. While

the mouth is typically included in the digestive system, it can also serve as a

passageway for air entering the respiratory system. Th e lower respiratory

tract consists of the larynx, trachea, and the bronchial and alveolar

tubes that form a large, branching network of passageways within the

lungs. Th is branching bronchial tree within each lung begins as a

large, fi nger-sized tube called the main or principal bronchus

and terminates in the lungs as the microscopic air sacs

called alveoli.

Like other systems that form an environmental

 exchange surface with the cardiovascular system,

the respiratory system forms an extensive surface

area in contact with the capillaries. It is estimated

that the surface area of the small dead-end air

sacs in  the lungs is about the size of a tennis

court. Th is extensive interface is essential for

the exchange of oxygen and carbon dioxide

between the inhaled air and the blood. If

body cells are deprived of oxygen, they cannot function and they die as a result. So the

 acquisition of oxygen through the respiratory passageways and its subsequent

exchange with the capillary blood is an

important function of the respiratory

system.

In addition to gas exchange, the

portion of the respiratory passageways

referred to as the larynx is responsible

for generating the sound waves that we

manipulate into voice. Internal folds in

the lining of the larynx, the vocal folds,

vibrate as air passes upward from the

lungs to produce the vibrations. For

this reason the larynx is oft en referred

to as the voice box.

17 Respiratory System

Find

pper Respiratory Tract

Sagittal section of head

Medial view

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Frontal section of head

Anterior view

 1 Nasal cavity

 2 Superior nasal concha

 3 Middle nasal concha

 4 Inferior nasal concha

 5 Torus tuberius

 6 Frontal sinus

 7 Ethmoid air cell

 8 Sphenoidal sinus

 9 Hard palate

10 Oral cavity

 11 Soft palate

12 Nasopharynx

13 Oropharynx

14 Laryngopharynx

15 Epiglottis

16 Tongue

17 Frontal lobe

18 Parietal lobe

19 Occipital lobe

20 Corpus callosum

21 Lateral ventricle

22 Pons

23 Cerebellum

24 Fourth ventricle

25 Medulla oblongata

26 Nasal septum

27 Maxillary sinus

28 Temporalis

29 Masseter

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31 Orbit

32 Intervertebral disc

33 Vertebral body

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The lower respiratory tract Lower Respiratory Tract arises as an outgrowth of

Lower respiratory tract and lungs in situ

Anterior view

the tubular gut during embryonic development. This anterior outgrowth of the gut tube begins at the

larynx (voice box), which is the upper expanded portion of the lower respiratory tract. It continues

from the neck into the thorax as the trachea (windpipe), and forms a large branching network of

tubes that enter the lungs, the bronchial tree. The pages that follow show the tubular organs and

histology of the lower respiratory tract.

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Dissection of lower respiratory tract and lungs in situ

Anterior view

 1 Thyroid cartilage of larynx

 2 Cricoid cartilage of larynx

 3 Trachea

 4 Main (primary) bronchus

 5 Right lung

 6 Left lung

 7 Bronchial tree

 8 Thyroid gland

 9 Common carotid artery

10 Subclavian artery

 11 Vagus nerve

12 Esophagus

13 Aorta

14 Pulmonary artery

15 Pulmonary vein

16 Inferior vena cava

17 Diaphragm

18 Stomach

19 Phrenic nerve

20 Rib

21 Intercostal muscle

22 Anterior scalene muscle

23 Thyrohyoid muscle

24 Cricothyroid muscle

25 Spleen

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Larynx

Laryngeal cartilages

Anterior view

Laryngeal cartilages

Posterior view

Laryngeal cartilages

Superior view

The entrance to the trachea is an expanded region called the larynx, or

voice box. A series of large cartilages form the walls of this region. The

soft tissue lining of the laryngeal cartilages folds into the larynx to form the vocal folds, fl aps of

tissue that lie across the opening of the larynx. Within the edges of the vocal folds are the vocal

cords, two bands of elastic tissue that can be stretched and positioned in different shapes by

laryngeal cartilages and muscles. As air is moved past the taut vocal cords, they vibrate to

produce the many different sounds of speech. During swallowing, the vocal cords assume a

function not related to speech; they are brought into tight apposition to each other to close off

the rima glottidis, the entrance to the lower larynx and trachea.

 1 Epiglottis

 2 Thyroid cartilage

 3 Thyroid tubercle (Adam’s apple)

 4 Superior cornu

 5 Inferior cornu

 6 Cricothyroid membrane

 7 Cricoid cartilage

 8 Arytenoid cartilage

 9 Corniculate cartilage

10 Trachea

 11 Vocal fold

12 Vocal ligament

13 Rima glottidis

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Trachea and Bronchial Tree

Photomicrograph of tracheal wall

100x

Dissection of lower

respiratory tract

Anterior view

The trachea, “windpipe,” is the conduction tube that

transports the air to and from the lungs. It is reinforced by U-shaped cartilages.The trachea branches

into two tubes called bronchi that enter the lungs. Each bronchus serves as the trunk of a highly

branched, tree-like network of bronchial tubes that become progressively narrower, shorter, and more

numerous as they spread throughout the tissues of the lung. These small tubes eventually terminate as

the small, dead-end air sacs called alveoli, the principal site of gas exchange between air and blood.

 1 Epiglottis

 2 Thyroid cartilage

 3 Cricoid cartilage

 4 Trachea

 5 Right main (primary) bronchus

 6 Left main (primary) bronchus

 7 Lobar (secondary) bronchus

 8 Segmental (tertiary) bronchus

 9 Bronchiole

10 Fibromuscular membrane

 11 Tracheal ring

12 Hyaline cartilage of tracheal ring

13 Tunica mucosa (pseudostratified)

14 Tela submucosa (areolar ct)

15 Tunica adventitia (dense ct)

16 Bronchiole cartilage (hyaline)

17 Alveolar spaces

18 Vein with red blood cells (rbc)

19 Pulmonary vein with rbcs

Section of trachea

Anterolateral view

Photomicrograph of alveoli and

small bronchial tube

100x

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The major difference between the arteries and veins of the abdomen

is the fact that all the visceral venous return from the capillaries of the

digestive system and spleen pass via the hepatic portal system to the

Abdominal Vessels

capillaries of the liver before returning to the heart. Within the liver, both the hepatic artery and hepatic portal vein branch to

form a complex network of specialized capillaries called the hepatic sinusoids. The hepatic sinusoids then drain into the

hepatic veins to return the blood to the inferior vena cava.

Abdominal veins

Dissection of abdomen showing arteries and veins of the intestines

Anterior view

 1 Inferior vena cava

 2 Hepatic portal vein

 3 Superior mesenteric vein

 4 Right colic vein

 5 Inferior mesenteric vein

 6 Renal vein

 7 Superior mesenteric artery

 8 Inferior mesenteric artery

 9 Middle colic artery

10 Marginal artery

 11 Left colic artery

12 Common iliac artery

13 External iliac artery

14 Internal iliac artery

15 Superior gluteal artery

16 Inferior gluteal artery

17 Obturator artery

18 Internal pudendal artery

19 Lateral sacral artery

20 Superior vesical artery

21 Vaginal artery

22 Obliterated umbilical artery

23 Uterus

24 Bladder

25 Prostate

26 Rectum

27 Stomach

28 Kidney

29 Upper bands of sacral plexus

30 Sympathetic trunk

31 Inferior vesical artery

32 Middle rectal artery

33 Obturator nerve

34 Uterine artery

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The common iliac arteries, the terminal branches of the

aorta, carry all of the blood supply to the lower limbs and

pelvis. All pelvic viscera, along with the body wall anatomy

Pelvic Vessels

of the pelvis and perineal regions, receive their blood supply from the internal iliac artery. Numerous

branches arise from the internal iliac artery to supply the pelvic wall, the perineum, and the gluteal

region. Other branches course into the pelvic cavity to supply the viscera. The veins are similar in

name and course with the corresponding arteries.

Dissection of pelvic arteries of female

Medial view, anterior at left

Dissection of pelvic arteries of male

Medial view, anterior at right

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As in the upper limb, the main arterial

pathway into the lower limb consists of

a single, major arterial roadway that

Inferior Limb Vessels

gradually tapers as it gives rise to numerous branches on its pathway through the limb. This large

arterial roadway begins as the external iliac artery in the pelvis, passes beneath the inguinal ligament

to enter the thigh as the femoral artery, passes to the back of the knee to become the popliteal artery,

and in the proximal aspect of the leg bifurcates into the anterior tibial and posterior tibial arteries,

which course through the leg and into the foot.

Dissection of gluteal region showing gluteal arteries and nerves

Posterior view

 1 Superior gluteal artery

 2 Inferior gluteal artery

 3 Internal pudendal artery

 4 Femoral artery

 5 Deep artery of thigh

 6 Muscular branches of femoral

 7 Femoral vein

 8 Great saphenous vein

 9 External iliac artery

10 Internal iliac artery

 11 External iliac vein

12 Common iliac artery

13 Aorta

14 Gluteus maximus muscle

15 Sacrotuberous ligament

16 Piriformis muscle

17 Spermatic cord (cut)

18 Penis (cut)

19 Adductor longus muscle

20 Rectus femoris muscle

21 Vastus intermedius muscle

22 Gracilis muscle

23 Vastus lateralis muscle

24 Vastus medialis muscle

25 Fascia lata

26 Sartorius muscle

27 Iliacus muscle

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Dissection of femoral vessels in femoral triangle

Anterior view

Dissection of vessels of inferior limb

Anterior view

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Inferior Limb Vessels

 1 Popliteal artery

 2 Anterior tibial artery

 3 Posterior tibial artery

 4 Fibular artery

 5 Superior lateral genicular artery

 6 Inferior lateral genicular artery

 7 Inferior medial genicular artery

 8 Femoral vein

 9 Great saphenous vein

10 Femoral artery

 11 Superficial epigastric artery

12 Superficial epigastric vein

13 External pudendal vein

14 Superficial circumflex iliac vein

15 Superficial circumflex iliac artery

16 Femoral nerve

17 Soleus muscle

18 Popliteus muscle

19 Subcutaneous layer

20 Fascia lata

21 Sartorius muscle

22 Adductor longus muscle

23 Biceps femoris muscle

24 Semitendinosus muscle

25 Scrotum

Dissection of popliteal and crural arteries

Posterior view

Dissection of proximal crus revealing arteries

Posterior view

Dissection of popliteal region revealing arteries

Posterior view

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Similar to the veins of the upper limb, the venous pathways in the lower limb consist of both deep veins that accompany the

arteries, and superfi cial veins that course through the hypodermis. In the foot and leg, the deep veins form vena comitans with

their arterial counterparts; however, the more proximal popliteal and femoral veins are large single vessels accompanying

their associated arteries. Two major superfi cial venous channels receive numerous tributaries from smaller superfi cial veins

throughout the lower limb. These major superfi cial veins are the small saphenous vein and the great saphenous vein. Unlike

the upper limb, the majority of venous blood fl ow through the lower limb passes via the deep veins. Anastomosing veins

between the saphenous veins and the deep veins have one-way valves. The valves direct blood fl ow to the deep veins

where contractions of surrounding skeletal muscles facilitate movement of the blood toward the heart.

Dissection of femoral vein and tributaries in femoral triangle

Anterior view

Dissection of great saphenous vein

Anteromedial view

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Superior Limb Vessels

Dissection of antebrachial arteries

Anterior view

Dissection of palmar arterial arch and branches to digits

Anterior view

 1 Brachial artery

 2 Ulnar artery

 3 Radial artery

 4 Anterior interosseous artery

 5 Superficial palmar arch

 6 Common digital artery

 7 Proper digital artery

 8 Deep palmar arch

 9 Cephalic vein

10 Median cubital vein

 11 Basilic vein

12 Median antebrachial vein

13 Accessory cephalic vein

14 Brachial vein

15 Interosseous membrane

16 Transverse carpal ligament

17 Supinator muscle

18 Pronator quadratus muscle

19 Flexor digitorum superficialis tendons

20 Flexor digitorum profundus tendons

21 Biceps brachii muscle

22 Triceps brachii muscle

23 Pectoralis major muscle

24 Deltoid muscle

25 Deltopectoral groove

26 Serratus anterior muscle

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Within the upper limb there are two sets of veins: deep veins that accompany the arteries, and superfi cial veins that course

through the hypodermis without arterial counterparts. The deep veins, running with the arteries of the upper limb, have the

same names as their arterial counterparts. These veins are signifi cantly smaller than the arteries they accompany and form

vena comitans with anastomotic channels around the arteries. The superfi cial veins of the upper limb are large and numerous.

There are three major superfi cial veins into which all the other superfi cial veins fl ow; they are the basilic vein, cephalic vein,

and median cubital vein. The median cubital vein is a connecting vein between the cephalic vein and the basilic vein. The

cephalic and basilic veins eventually pass deep to join the axillary vein at the proximal end of the limb. Most of the venous

return from the upper limb passes through the superfi cial veins.

Dissection of superfi cial vein of upper limb

Medial view of left upper limb

Dissection of cephalic vein

Anterior view

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The branches of the aorta that supply the thoracic

region can be divided into two principal groups —

those that supply the thoracic body wall and those

Thoracic Vessels

that supply thoracic viscera. Two arterial supply routes carry blood into the thoracic body wall. Posteriorly the aorta courses vertically down the vertebral column, while anteriorly the internal thoracic

arteries arise from the subclavian arteries and course vertically down the inside of the sternum.

Between these anterior and posterior supply arteries are interconnecting collateral arteries. These

collateral vessels are the anterior intercostal arteries and the posterior intercostal arteries, which supply the tissues of the intercostal spaces and form collateral circuits between the anterior and posterior arterial pathways. All thoracic viscera receive their blood supply from branches of the aorta. The

thoracic viscera include the heart, lungs with their associated bronchial tubes, and the esophagus.

Dissection of vessels of posterior thoracic wall

Anterior view

 1 Aorta

 2 Posterior intercostal artery

 3 Posterior intercostal vein

 4 Azygos vein

 5 Hemi-azygos vein

 6 Accessory hemi-azygos vein

 7 Superior vena cava

 8 Brachiocephalic vein

 9 Subclavian vein

10 Internal jugular vein

 11 Inferior vena cava

12 Right atrium (cut)

13 Left subclavian artery

14 Left common carotid artery

15 Right common carotid artery

16 Hepatic vein

17 Trachea

18 Diaphragm

19 Esophageal hiatus

20 Subcostal muscle

21 Innermost intercostal muscle

22 Esophagus

23 Sympathetic trunk nerve

24 Thoracic lymphatic duct

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Like the arterial supply to the thoracic wall, the venous drainage returns via both anterior-wall and posterior-wall drainage

veins. The veins of the anterior wall have the same names as their arterial counterparts, while the veins of the posterior wall

differ in name and structure. Unlike the aorta, which is the posterior-wall supply artery, the superior vena cava and inferior

vena cava diverge from the posterior thoracic wall to enter the thoracic cavity and return their contents to the heart. In the

absence of vena cavae in the posterior thoracic wall, an azygos system of veins is formed to drain the body wall and the

thoracic viscera. These azygos veins communicate with the superior vena cava to return their contents to the heart. With

the exception of the azygos veins, the veins are similar to the arteries in name and distribution.

Dissection of vena cavae and tributaries

Anterior view

Dissection of azygos veins

Anterior view

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Like the thorax, the abdomen has somatic ar- Abdominal Vessels

teries that supply the abdominal muscle wall

and visceral arteries that supply the viscera of the abdominal cavity. These vessels follow the same

pattern observed in the thoracic region; that is, the abdominal body wall has both anterior (epigastric

arteries) and posterior (aorta) supply pathways that form interconnecting collateral arteries, while the

viscera receive branches from the aorta — celiac artery to the foregut, superior mesenteric artery to

the midgut, inferior mesenteric artery to the hindgut, and renal arteries to the kidneys.

Deep dissection of abdomen showing renal vessels

Anterior view

Dissection of abdomen showing celiac branches and supply of foregut viscera

Anterior view, stomach reflected upward

Branches of celiac artery Branches of celiac artery

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Superior mesenteric artery

Inferior mesenteric artery

Dissection of abdomen showing arterial supply of midgut and hindgut viscera

Anterior view

 1 Aorta

 2 Celiac artery

 3 Splenic artery

 4 Common hepatic artery

 5 Left gastric artery

 6 Right gastric artery

 7 Left gastro-omental artery

 8 Right gastro-omental artery

 9 Proper hepatic artery

10 Gastroduodenal artery

 11 Superior pancreaticoduodenal artery

12 Superior mesenteric artery

13 Middle colic artery

14 Marginal artery

15 Right colic artery

16 Ileocolic artery

17 Jejunal arteries

18 Ileal arteries

19 Inferior mesenteric artery

20 Left colic artery

21 Sigmoid artery

22 Superior rectal artery

23 Renal artery

24 Segmental arteries

25 Common iliac artery

26 Inferior vena cava

27 Hepatic vein

28 Renal vein

29 Hepatic portal vein

30 Superior mesenteric vein

31 Inferior mesenteric vein

32 Splenic vein

33 Suprarenal vein

34 Testicular vein

35 Kidney

36 Liver

37 Stomach

38 Transverse colon

39 Suprarenal gland

40 Pancreas

41 Spleen

42 Duodenum

43 Ascending colon

44 Descending colon

45 Ileum

46 Diaphragm

47 Ureter

48 Psoas major muscle

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