Thorax

THE THORAX

Bernadett Pua Velasco, M.D.

Thorax  Chest  Region

of the body between the neck and abdomen  Framework: thoracic cage

Surface landmarks of the thorax ANTERIOR CHEST WALL  Suprasternal notch  Sternal angle (angle of louis)  Xiphoid process  Subcostal angle  Costal margin  Clavicle  Ribs  Nipple

Surface landmarks of the thorax POSTERIOR CHEST WALL  Spinous process of thoracic vertebrae  Scapula  Superior

angle

 Spine  Inferior

angle

Lines of Orientation  Midsternal  Midclavicular  Anterior

axillary  Posterior axillary  Midaxillary  Scapular

Lines of Orientation  Midsternal  Midclavicular  Anterior

axillary  Posterior axillary  Midaxillary  Scapular

Lines of Orientation  Midsternal  Midclavicular  Anterior

axillary  Posterior axillary  Midaxillary  Scapular

Thoracic Cage  Anterior:

sternum and costal cartilages  Lateral: ribs and intercostal spaces  Posterior: thoracic vertebrae

Thoracic Cage  Protects

the lungs and heart  Attachment for the muscles of thorax, UE, abdomen and back

Thoracic Cavity  Median:

mediastinum

 heart

 Lateral  Pleura

and lungs

Openings of the Thorax  Thoracic

outlet (inlet)

 Anterior:

superior part of manubrium sterni  Lateral: 1st ribs  Posterior: T1

Openings of the Thorax Lower opening  Anterior:

xiphisternal joint  Lateral: costal margin  Posterior: T12

Structure of the Thoracic Wall  Anterior:

sternum and costal cartilages  Lateral: ribs and intercostal spaces  Posterior: thoracic vertebra  Superior: suprapleural membrane  Inferior: diaphragm

Sternum  Flat

bone  3 parts:  Manubrium

sterni  Body of the sternum  Xiphoid process

Costal Cartilages  Hyaline

cartilage  Connects the upper 7 ribs to the sternum and the 8th-10th ribs to the cartilage above them  Function: gives elasticity and mobility of the thoracic wall

Ribs  12

pairs  Attached posteriorly in the thoracic vertebrae  1st 7 pairs: attached anteriorly in the sternum  8th-10th pairs: attached to each other and to 7th rib via costal cartilages  11th-12th pairs: no anterior attachment

Typical Rib  Long,

twisted, flat bone  Superior border: round and smooth  Inferior border: sharp and thin, has costal groove

Typical Rib  Head  Neck  Tubercle  Shaft  Angle

Intercostal Spaces 3

muscles of respiration

 External

intercostals  Internal intercostals  Innermost intercostals

External Intercostal Muscles  Superficial

layer  Downward and forward  tubercle to the costochondral junction  Anterior intercostal membrance

Internal Intercostal Muscle  Intermediate

layer  Downward and backward  Sternum to the angle of the ribs  Posterior intercostal membrane

Innermost Intercostal Muscle  Deepest

layer  Incomplete muscle layer  Crosses more than one intercostal space  Internal: endotracheal fascia and parietal pleura  External: intercostal nerves and vessels

Suprapleural Membrane  Dense

fascial layer  Lateral: medial border of 1st rib  Superior: tip of C7 transverse process  Medial: investing layer of the thorax into the neck  Functions: resists changes in intrathoracic pressure and protects cervical pleura

Endotracheal Fascia  Thin

layer of connective tissue  Function: separates parietal pleura to the thoracic wall

Diaphragm  Primary

muscle of respiration  Dome shaped  Openings:  Aortic-

thoracic duct, azygos vein  Esophageal- vagus nerves, (L) gastric vessels  Caval- terminal branches of ® phrenic nerve

Thoracic Cavity  Median  Lateral

(mediastinum)

Mediastinum  Movable

partition  Superior: thoracic outlet, root of the neck  Inferior: diaphragm  Anterior: sternum  Posterior: T12

Mediastinum  Content:

thymus, heart and large blood vessels, trachea, esophagus, thoracic duct and LN, vagus and phrenic nerve, sympathetic trunk

Mediastinum  Superior  Inferior  Anterior  Middle  posterior

Superior Mediastinum  Anterior:

manubrium sterni  Posterior: T1-T4  Content: thymus, large veins and arteries, trachea, esophagus, thoracic duct, sympathetic trunk

Inferior Mediastinum  Anterior:

body of sternum  Posterior: T5-T12  Content: thymus, heart within the pericardium, phrenic nerve, esophagus, thoracic duct, descending aorta, sympathetic trunk

Pleurae  Parietal:

lines the thoracic wall  Visceral: covers the outer surface of the lungs

Pleural Space  Slitlike

space  Filled with pleural fluid  Function: covers the surface of the pleura and minimizes friction

Visceral Pleura  Approximates

the surface of the lungs  Pulmonary plexus (ANS)  Sensitive to stretch  insensitive to pain and touch

Parietal Pleura  Cervical  Costal  Diaphragmatic  Mediastinal

Parietal Pleura  Sensitive

to touch, pain, T, P  Costal: intercostal nerves  Mediastinal: phrenic nerves  Diaphragmatic: phrenic nerves and lower 6 intercostal nerves

Costodiaphragmatic recess  Scapular

line: 2 inches  MAL: 3 inches  MCL: 1 inch

Surface Landmarks of the Pleura  Cervical:

2.5cm above the junction of medial and mid 3rd of clavicle  Anterior:  

®- behind the SCJ to the XS (L)- same as ® 4th

CC= lateral margin of sternum (cardiac notch) then going sharply to the XSJ

Surface Landmarks of the Pleura  Posterior  MCL:

8th rib  MAL: 10thrib  Lateral border of erector spinae: 12th rib

Trachea  Mobile

tube  5 inches long, 1 inch in diameter  Fibroelastic wall with U-shaped bars of hyaline cartilage  Lined with trachealis posteriorly

Trachea  From

the cricoid cartilage (C6) to the sternal angle (T4)  Bifurcates into bronchus (Carina)  Branches of the vagus and recurrent laryngeal nerves  Sympathetic trunk

Trachea  Anterior:

sternum, thymus, (L) brachiocephalic vein, origins of BC and (L) CC artery, arch of aorta  Posterior: esophagus, (L) recurrent laryngeal nerve  ®: azygos vein, ® vagus nerve, pleura  (L): arch of aorta, (L) CC artery, (L) subclavian artery, (L) vagus nerve, (L) phrenic nerve, pleura

Right Main Bronchus  Wider,

shorter, more vertical  2.5cm long  Divisions  Superior

lobar  Middle lobar  Inferior lobar

Left Main Bronchus  Narrower,

longer, more horizontal

 5cm

long  Divisions:  Superior

lobar  Inferior lobar

Lungs  Conical

in shape  Situated on either side of the mediastinum  Covered with visceral pleura  Blunt apex  Concave base  Convex costal surface  Concave mediastinal surface

Lungs  Medially:

hilum  Left lung: cardiac notch

Right Lung  Slightly

larger  Divided:  Upper  Middle  lower

Left Lung  Divided:  Upper  Lower

Lung Fissures  Oblique

fissure:

 Inferior

border upward and backward across the medial and costal surfaces until it reaches the posterior border 2 ½ inches below the apex

Lung Fissures  Oblique  Root

fissure:

of the scapular spine, obliquely downward, laterally and anteriorly, following the course of the 6th rib to the 6th CC junction



Lung Fissures  Horizontal  Across

fissure:

the costal surface at the level of 4th costal cartilages to meet the oblique fissure in the MAL

Lung Fissures  Horizontal  4th

fissure:

CC to meet the oblique fissure in MAL

Bronchopulmonary Segment  Anatomic,

functional and surgical units  Components:  Segmental

bronchus  Branch of pulmonary artery  Lymphatic vessel  Autonomic nerve supply

Bronchopulmonary Segment  Primary

(Main) bronchus  Secondary (Lobar) bronchus  Tertiary (Segmental) bronchus

Bronchopulmonary Segment  Subdivision

of the lung lobe  Pyramid in shape  Surrounded by connective tissue  Has segmental bronchus, segmental artery, lymph vessels, autonomic nerves  Segmental vein lies between the adjacent bronchopulmonary segment  Can be removed surgically

Bronchopulmonary Segment  Right

lung

 Superior Apical,

posterior, anterior

 Middle Lateral,

medial

 Inferior Superior

(apical), medial basal, anterior basal, lateral basal, posterior basal

Bronchopulmonary Segment  Left

lung

 Superior Apical,

posterior, anterior, superior lingular, inferior

lingular  Inferior Superior

(apical), medial basal, anterior basal, lateral basal, posterior basal

Bronchopulmonary Segment  Main

bronchus  Lobar bronchus  Segmental bronchus  Bronchioles  Terminal bronchioles  Respiratory bronchioles  Alveolar ducts  Alveolar sacs

Respiratory Zone  Respiratory

bronchiole  Alveolar duct  Alveoli

Alveoli  Alveolar

duct  Alveolar sac  Alveolus

Lungs  Bronchial

arteries  descending aorta  Bronchial veins azygos and hemiazygos veins  Pulmonary artery alveoli  Pulmonary vein left atrium