Thorax

Anhui Medical University Depart of Human Anatomy, Jiao Yi

The Intercostal Spaces, the Pleura, the Pleural Cavity and the lung

Boundaries and DivisionsBoundaries Superior － jugular notch, st

ernoclavicular joint, superior border of clavicle, acromion, spinous processes of C7

Inferior － xiphoid process, costal arch, 12th and 11th ribs, vertebra T12

Regions Thoracic wall Thoracic cavity

Landmarks Sternal angle connects 2nd costal

cartilage laterally ， corresponds with The lower border of 4th thoraci

c vertebra The bifurcation of trachea in th

e adult The beginning of aortic arch w

hich ends posteriorly at the same level

The esophagus is crossed by the left main bronchus

Reference lines of thorax

Anterior median line Sternal line Midclavicular line Parasternal line Anterior axillary line Posterior axillary line Midaxillary line Scapular line Posterior median line

Thoracic wall Skin Superficial fascia

Thoracoepigastric v.( 胸腹壁静脉） Supraclavicular n. Anterior and lateral cutan

eous branches of intercostal n.

Deep fascia

The lymphatic drainage of thorax

The lymphatic drainage of thoracic wall

To axillary lymph nodes To parasternal lymph nodes

(along internal thoracic vessels)

To intercostals lymph nodes from deeper structures

Intercostal space

Posterior intercostal v.

Posterior intercostal a.

Intercostal n.

The muscles of thoraxExtrinsic muscles Pectoralis major Pectoralis minor Serratus anterior（锯状肌）

The muscles of thorax

Intrinsic muscles Intercostales externi Intercostales interni

Intercostales externi Origin: lower border of ri

b Insertion: upper border o

f rib below origin Action: elevate ribs addin

g in forced inspiration Replaced anteriorly by ex

ternal intercostals membrane.

Intercostales interni Origin: upper border of ri

b Insertion: lower border of

rib above origin Action: depress ribs for fo

rced expiration Replaced posteriorly by in

ternal intercostals membrane.

The Pleura 胸膜General features Serous membranes formi

ng closed sacs Two layers

Visceral pleura － adheres to lung, continuous with parietal pleura at root of lung

Parietal pleura － lines the thoracic cavity

Two pleural layers continue with each other at root of lung forming closed potential space － pleural cavity 胸膜腔 Contains a small amount

of pleural fluid Subatmospheric pressur

e in it

Named parts of parietal pleura Cupula of pleura 胸膜顶 － extends up into the n

eck, over the apex of lung, 2 ～ 3cm above the medial third of clavicle

Costal pleura 肋胸膜 － lines the inner surface of the wall of the chest

Mediastinal pleura 纵隔胸膜 - Lines mediastinum Diaphragmatic pleura 膈胸膜－ Lines diaphragm

Pleura recesses 胸膜隐窝－ potential spaces of pleural cavity which lungs are not occupied in quiet respiration

Costodiaphragmatic recess肋膈隐窝－ are the slit-like intervals between costal and diaphragmatic pleurae on each side, the lowest point of pleural cavity

Costomediastinal recess 肋纵隔隐窝－ on the left side between the mediastinal pleural and costal pleura

The surface projection of lower border of lung and pleurae

Lower border

Midclavicular lines

Midaxillary lines

Sides of the vertebral column

Lungs 6th rib 8th rib 10th rib

Pleura 8th rib 10th rib 12th rib

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

Thoracic aorta 胸主动脉 Main branches

Parietal branches Nine pairs posterior interc

ostals arteries 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.

The Lungs 肺Position: located in the tho

racic cavity by both sides of mediastinum

General features Cone-shaped, the right l

ung is shorter and broader, the left one is longer and narrower

The Lungs 肺 Apex of lung － rises 2

～ 3 cm above the medial third of clavicle into neck

Base － concave, related to diaphragm, also called diaphragmatic surface

Costal surface － large, convex, related to thoracic wall

Medial surface － concave, related to mediastinum and vertebrae Hilum of lung 肺门： area on

medial surface where structures in root enter or leave lung

Root of lung 肺根 Contents

Principal bronchus Pulmonary artery and vein Nerves and lymphatics

Surrounded by connective tissue

Order of structures in the root of lung From before backward: 1.The superficial pulmonary

vein, 2.The pulmonary artery, 3.The principal bronchus, 4.The inferior pulmonary vein.

Lobes and Fissure Right lung

Two fissures : horizontal an oblique

Three lobes : superior, middle, inferior

Left lung One fissure : oblique Two lobes : superior

and inferior

Arteries of thorax

Pulmonary trunk Arises from right ventricle Runs up, back ,and to the

left Bifurcates inferior to

aortic arch into right and left pulmonary arteries, one for each lung

Arteries of thorax

Pulmonary arteries Right pulmonary artery －

passes posterior to ascending aorta and superior vena cava to hilum of right lung

Left pulmonary artery － passes anterior to descending aorta and left main bronchus to hilum of left lung

Arterial ligament 动脉韧带－ remnant of ductus arteriosus, connects bifurcation of pulmonary trunk to inferior border of aortic arch

Ascending aorta 升主动脉 Runs upward, forward

and to the right, Extends to level of seco

nd right sternocostal joint

Branches: right and left coronary arteries

Thoracic aorta 胸主动脉 Main branches

Visceral branches Bronchial branches: one or

two for each lung Esophageal branches Pericardial branches

Veins of thoraxBrachiocephalic veins Formed by union of internal

jugular and subclavian veins posterior to the sternoclavicular joint

Angle of union is termed venous angle

Veins of thoraxSuperior vena cava Formed by union of right a

nd left brachiocephalic veins behind the right sternocostal synchorndrosis of first rib

Runs vertically down on right of ascending aorta

Veins of thoraxSuperior vena cava

Joined by azygos vein at level of sternal angle

Enters right atrium at level of lower border of third right sternocostal joint

Collects blood from veins of upper half of body

Azygos vein 奇静脉 Begins as continuation of ri

ght ascending lumbar vein Ascending along the right si

de of vertebral column

Azygos vein 奇静脉 Joins superior vena cava by

arching 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 － hemi-azygos v. 半奇静脉 and accessory hemi-azygos v. 副半奇静脉 , which receive most left posterior intercostals vein and left bronchial veins

Thoracic duct 胸导管 Begins in front of L1 as a dila

ted sac, the cisterna chyli 乳糜池 , which formed by joining of left and right lumbar trunks and intestinal trunk

Thoracic duct 胸导管 Enter thoracic cavity by passi

ng through the aortic hiatus of the diaphragm and ascends along on the front of the vertebral column, between thoracic aorta and azygos vein

Thoracic duct 胸导管 Travels upward, veering to

the left at the level of T5 At the root of the neck, it tu

rns laterally and arches forwards and descends to enter the left venous angle

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 右淋巴导管 Formed by union of right j

ugular, subclavian, and bronchomediastinal trunks

Ends by entering the right venous angle

Receives lymph from right half of head, neck, thorax and right upper limb

Anterior branches of thoracic nerves

1.Intercostal nerves (anterior rami of T1- T11

Anterior branches of thoracic nerves

2.Subcostal nerve (anterior ramus of T12): follows inferior border of T12 rib and passes into abdominal wall

Phrenic nerve 膈神经 Descends over scalenus an

terior to enter thorax Accompanied by pericard

iophrenic vessels and passes anterior to lung roots between mediastinal pleura and pericardium to supply motor and sensory innervation to diaphragm

Phrenic nerve 膈神经 Sensory fibers supply to

pleurae, pericardium and peritoneum of diaphragm; usually right phrenic nerve may be distributed on liver, gallbladder and biliary system.

Left vagus nerve 左迷走神经 Enter thoracic inlet between l

eft common carotid and left subclavian arteries, posterior to left brachiocephalic vein

Crosses aortic arch where left recurrent laryngeal nerve branches off

Left vagus nerve 左迷走神经 Passes posterior to left lung ro

ot Forms anterior esophageal pl

exus 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 右迷走神经 Enter thoracic inlet on right

side of trachea Travels downward posterior

to right brachiocephalic vein and superior vena cava

Passes posterior to right lung root

Right vagus nerve 右迷走神经 Forms posterior esophageal ple

xus 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 喉返神经 Right one hooks around right s

ubclavian 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

Recurrent laryngeal nerves 喉返神经 Innervations: laryngeal mu

cosa below fissure of glottis , all laryngeal muscles except cricothyroid

Thoracic sympathetic trunk 胸交感干 Branches of sympathetic trunk

to thoracic plexuses Greater splanchnic nerve 内脏大神经 formed by preganglion

ic fibers from T5~T9 ganglia, and relay in celiac ganglion.

Thoracic sympathetic trunk 胸交感干 Lesser splanchnic nerve 内脏小神经 formed by preganglio

nic 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.

Experimental guide:

1. Cut through the clavicular attachment of the subclavius muscle and reflect the clavicle.

2. Dissect the intercostal spaces. 3. Open the thoracic cavity. 4. Observe the posterior aspect of the anterior t

horacic wall. 5. Observe the pleura. 6. Cut off the root of the lung. 7. Look for the intercostal vessels and nerve.

The Mediastinum

The Mediastinum 纵隔 Concept － all of organs b

etween 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.

Subdivisions of mediastinum Superior mediastinum 上纵隔 Inferior mediastinum 下纵隔

Anterior mediastinum Middle mediastinum Posterior mediastinum

Superior mediastinum 上纵隔Locating － from inlet of t

horax to plane extending from level of sternal angle anteriorly to lower border of T4 vertebra posterioly

Superior mediastinum 上纵隔Contents Superficial layer

Thymus Three veins

Left brachiocephelic v.

Right brachiocephelic v.

Superior vena cava

Middle layer Aortic arch and its t

hree branches Phrenic n. Vagus n.

Posterior layer Trachea Esophagus Thoracic duct

Triangule of ductus arteriosus 动脉导管三角 Bounded by phrenic n., left vag

us n. and left pulmonary a. Contents － arterial ligament ,

left recurrent n. and superficial cardiac plexuses

Inferior mediastinum 下纵隔Anterior mediastinum 前纵隔 Location － posterior to bo

dy of sternum and attached costal cartilages, anterior to heart and pericardium

Contents － fat, remnants of thymus gland, anterior mediastinal lymph nodes

Middle mediastinum 中纵隔 Location － between ante

rior mediastinum and posterior mediastinum

Contents: heart and pericardium, beginning or termination of great vessels, phrenic nerves, pericardiacophrenic vessels , lymph nodes,

Posterior mediastinum 后纵隔 Location － posterior to he

art 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

Right side of mediastnum

Root of lung

Pericardium

Superior vena cava

Phrenic n. & pericardiacophrenic a.

Left vagus n.

Azygos v.

Sympathetic trunk

Esophagus

Arch of azygos v.

Trachea

Inferior vena cava

Left side of mediastnum

Root of lung

Pericardium

Phrenic n. & pericardiacophrenic a.

Left vagus n.

Left recurrent n. Thoracic aorta

Sympathetic trunk

Greater splanchnic n

Aortic archThoracic duct

Left subclavian a.

Esophagus

Experimental guide:

1. On the right side of the mediastinum.

2. On the left side of the mediastinum. (Attention: Don’t cut off the heart.)