Internal thoracic artery descends into thorax
1.2cm lateral to edge of sternum, and ends at the sixth costal cartilage by dividing musculophrenic and superior epigastric arteries

Azygos vein
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Begins as continuation of right ascending lumbar vein
Ascending along the right side of vertebral column
Joins superior vena cava by aching above right lung root at level of T4 to
T5
Receives right posterior intercostals and subcostal veins plus some of bronchial, esophageal and pericardial veins, and hemiazygos vein
Tributaries – hemiazygos v.
and accessory hemiazygos v.
, which receive most left posterior intercostals vein and left bronchial veins

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To axillary lymph nodes
To parasternal lymph nodes
(along internal thoracic vessels)
To intercostals lymph nodes from deeper structures

lymph nodes of trachea, bronchi and lungs
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Pulmonary lymph nodes lie in the angles of bifurcation of branching lobar bronchi
Bronchopulmonary hilar lymph nodes － lie in the hilus of the lung
Tracheobronchial lymph nodes
－ situated above or below the bifurcation of trachea
Paratracheal lymph nodes
－ along each side of the trachea

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Anterior mediastinal lymph node lies anterior to the large blood vessels of thoracic cavity and pericardium; the efferents unite with those of paratracheal lymph nodes, to form the right and left bronchomediastinal trunks .
The left bronchomediastinal trunk terminates in thoracic duct, and right in the right lymphtic duct
Posterior mediastinal lymph nodes lie along the esophagus and thoracic aorta

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Intercostal nerves (anterior rami of
T1- T11): runs forward inferiorly to intercostals vessels in costal groove of corresponding rib, between intercostals externi and intercostals interni; first six nerves are distributed within their intercostals space, lower five intercostals nerves leave anterior ends of their intercostals spaces to enter abdominal wall
Subcostal nerve (anterior ramus of
T12): follows inferior border of T12 rib and passes into abdominal wall
Distribution: distributed to intercostales and anterolateral abdominal muscles, skin of thoracic and abdominal wall, parietal pleura and peritoneum

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T2 － sternal angle
T4 － nipple
T6 － xiphoid process
T8 － costal arch
T10 － umbilicus
T12 － midpoint between umbilicus and symphysis pubis

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Descends over scalenus anterior to enter thorax
Accompanied by pericardiophrenic vessels and passes anterior to lung roots between mediastinal pleura and pericardium to supply motor and sensory innervation to diaphragm
Sensory fibers supply to pleurae, pericardium and peritoneum of diaphragm; usually right phrenic nerve may be distributed on live, gallbladder and biliary system.

Left vagus nerve
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Enter thoracic inlet between left common carotid and left subclavian arteries, posterior to left brachiocephalic vein
Crosses aortic arch where left recurrent laryngeal nerve branches off
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Passes posterior to left lung root
Forms anterior esophageal plexus
Forms anterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity , then divides into anterior gastric and hepatic branches

Right vagus nerve
 Enter thoracic inlet on right side of trachea
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Travels downward posterior to right brachiocephalic vein and superior vena cava
Passes posterior to right lung root
Forms posterior esophageal plexus
Forms posterior vagal trunk at esophageal hiatus where it leaves thorax and passes into abdominal cavity, then divides into posterior gastric and celiac branches

Recurrent laryngeal nerves
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Right one hooks around right subclavian artery, left one hooks aortic arch
Both ascend in tracheo-esophageal groove
Nerves enter larynx posterior to cricothyroid joint, the nerve is now called inferior laryngeal nerve
 Innervations: laryngeal mucosa below fissure of glottis , all laryngeal laryngeal muscles except cricothyroid
Bronchial and esophageal branches

Thoracic sympathetic trunk
 Branches of sympathetic trunk to thoracic plexuses
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Greater splanchnic nerve formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion.
Lesser splanchnic nerve formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion.
The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure.

Boundaries
 Superior - jugular notch, sternoclavicular joint, superior border of clavicle, acromion, spinous processes of C7
 Inferior - xiphoid process, costal arch, 12th and 11th ribs, vertebra T12
Regions
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Thoracic wall
Thoracic cavity

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Jugular notch corresponds with
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The 2th thoracic vertebra in male, the 3th thoracic vertebra in female
Sternal angle connects 2nd costal cartilage laterally corresponds with
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The lower border of 4th thoracic vertebra
The bifurcation of trachea in the adult
The beginning of aortic arch which ends posteriorly at the same level
The esophagus is crossed by the left main bronchus

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Xiphoid process xiphisternal junction lies opposite the body of the 9th thoracic vertebra
Clavicle
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Inferior fossa of clavicle
Coracoid process
Ribs and intercostal spaces
Costal arch
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Infrasternal angle
Xiphocostal angle
Papillae

 Skin
 Superficial fascia
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Thoracoepigastric v.
Supraclavicular n.
Anterior and lateral cutaneous branches of intercostal n.
 Deep fascia

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Into pectoral ln.
from lateral and central parts of breast
Into apical and supraclavicular ln.
from superior part of breast
Into parasternal ln.
from medial part of breast
Into interpectoral ln.
from deep part of breast
The lymphatic capillaries of breast form an anastomosing network which is continuous across the midline with that of the opposite side and with that of the abdominal wall

Internal thoracic vessels
 Internal thoracic a.&v.
 Parasternal ln.
Endothoracic fascia

Extrinsic muscles
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Pectoralis major
Pectoralis minor
Serratus anterior
Intrinsic muscles
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Intercostales externi
Intercostales interni
Intercostales intimi
Transverses thoracis

Intercostales externi
 Origin: lower border of ri Ⅱ )
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Insertion: upper border of rib below origin
Action: elevate ribs adding in forced inspiration
Replaced anteriorly by external intercostals membrane.
Intercostales interni
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Origin: upper border of rib
Insertion: lower border of rib above origin
Action: depress ribs for forced expiration
Replaced posteriorly by internal intercostals membrane.

Posterior intercostal v.
Posterior intercostal a.
Intercostal n.

Shape and position
: dome-shaped between thorax and abdomen, consists of a peripheral muscular part and a central tendon
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Origin
Sternal part: xiphoid process
Costal part: lower six and costal cartilages
Lumbar part: arises by two crura from upper 2-3 lumbar vertebrae
Insertion: central tendon
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Weak areas
: triangular spaces without muscular tissue
Lumbocostal triangle : between costal and lumbar parts.
Sternocostal triangle : between costal and sternal parts.

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Aortic hiatus lies anterior to the body of the 12th thoracic vertebra between the crura. It transmits the aorta, thoracic duct
Esophageal hiatus for esophagus and vagus nerves at level of T10.
Vena cava foramen for inferior vena cava, through central tendon at T8 level
T8
T10
T12

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:
Contraction : the dome moving downward, increases the volume of thoracic cavity which results in inspiration, at the same time the intraabdominal pressure is increased assists in defecation, vomiting or child birth.
Relaxation : the dome returns to the former position, reduces the volume to the thoracic cavity, resulting in expiration.

Concept all of organs between the left and right mediastinal pleurae is called mediastinum. It extends from the sternum in front to the vertebral column behind, and from the thoracic inlet above to the diaphragm below.

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Superior mediastinum
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Inferior mediastinum
Anterior mediastinum
Middle mediastinum
Posterior mediastinum

Left vagus n.
Left recurrent n.
Phrenic n. & pericardiacophrenic a.
Root of lung
Pericardium
Esophagus
Left subclavian a.
Thoracic duct
Aortic arch
Thoracic aorta
Sympathetic trunk
Greater splanchnic n

Trachea
Left vagus n.
Arch of azygos v.
Azygos v.
Sympathetic trunk
Esophagus
Inferior vena cava
Superior vena cava
Phrenic n. & pericardiacophrenic a.
Root of lung
Pericardium

Locating - from inlet of thorax to plane extending from level of sternal angle anteriorly to lower border of
T4 vertebra posterioly
Contents
 Superficial layer
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Thymus
Three veins
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Left brachiocephelic v.
Right brachiocephelic v.
Superior vena cava

 Middle layer
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Aotic arch and its three branches
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Phrenic n.
Vagus n.

 Posterior layer
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Trachea
Esophagus
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Thoracic duct

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Anteriorly and to the left pleura, lung phrenic n., pericardiacophrenic vessels and vagus n.
Posteriorly and to the right trachea, esophagus, left recurrent n., thoracic duct, deep cardiac plexus
Superiorly - its three branches, left brachiocephalic v. and thymus
Inferiorly - pulmonary a., arterial ligament, left recurrent n., left principal bronchus and superficial cardiac plexus

Triangule of ductus arteriosus
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Bounded by phrenic n., left vagus n. and left pulmonary a.
Contents － arterial ligament , left recurrent n. and superficial cardiac plexuses

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Location - posterior to body of sternum and attached costal cartilages, anterior to heart and pericardium
Contents - fat, remnants of thymus gland, anterior mediastinal lymph nodes

Middle mediastinum
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Location - between anterior mediastinum and posterior mediastinum
Contents: hart and pericardium, beginning or termination of great vessels, phrenic nerves, pericardiacophrenic vessels , lymph nodes,

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Location - posterior to heart and pericardium, anterior to vertebrae T5 - T12
Contents : esophagus, vagus n., thoracic aorta, azygos system of veins, thoracic duct, thoracic sympathetic trunk, posterior mediastinal lymph nodes

 Anteriorly - trachea, bifurcation of trachea, left principal branchus, left recurrent n., right pulmonary a., anterior esophageal plexus, pericardium, left atrium, diaphragm

 Posteriorly - posterior esophageal plexus, thoracic aorta, thoracic duct, azygos v., hemiazygos v.,accessory hemiazygos v., right posterior intercostal v.

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Left - left common carotid a., left subclavian a., aortic arch, thoracic aorta, superior part of thoracic duct
Right - arch of azygos v.

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Anteriorly - left root of lung, pericardium and esophagus
Posterior - hemiazygos v., accessory hemiazygos v.,
Right - azygos v. and thoracic duct
Left - mediastinal pleura

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Begins in front of L1 as a dilated sac, the cisterna chyli, which formed by joining of left and right lumbar trunks and intestinal trunk
Enter thoracic cavity by passing through the aortic hiatus of the diaphragm and ascends along on the front of the vertebral column, between thoracic aorta and azygos vein
Travels upward, veering to the left at the level of T5
At the roof of the neck, it turns laterally and arches forwards and descends to enter the left venous angle

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Just before termination, it receives the left jugular, subclavian and bronchomediastinal trunks
Drains lymph from lower limbs, pelvic cavity, abdominal cavity, left side of thorax, and left side of the head, neck and left upper limb
Right lymphatic duct
 Formed by union of right jugular, subclavian, and bronchomediastinal trunks
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Ends by entering the right venous angle
Receives lymph from right half of head, neck, thorax and right upper limb

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Retrosternal space lies beween sternum and endothoracic fascia
Pretracheal space lies within superior mediastinum, between trachea, bifurcation of trachea and aortic arch
Retroesophagus space lies within superior mediastinum, beween esophagus and endothoracic fascia

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Continuation of aortic arch at lower border of T4
Courses downward on left side of, then in front of vertebral column
Passes through aortic hiatus of diaphragm at level of T12 vertebra to enter abdominal cavity
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Main branches
Parietal branches
 Nine pairs posterior intercostals arteries
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One pair subcostal artery
For lower nine intercostals spaces and upper part of abdominal wall; superior phrenic arteries supply the superior surface of the diaphragm.
Visceral branches
Bronchial branches: one or two for each lung
Esophageal branches
Pericardial branches