Respiratory Anatomy And Radiology

Lecture 4: Thoracic wall

• Thorax: superior portion of the trunk between the neck an the abdomen
- Thoracic cavity: space within the rib cage and the vertebral column
- Thoracic cage: the skeletal container that holds the thoracic cavity formed by horizontal bards of ribs and costal cartilages supported by the sternum and vertebrae.
- Diaphragm: sheets of membranous muscles that spans the lower thoracic aperture. Due its convexity upwards into the thoracic cavity, much of the lower half of the thoracic wall surround the abdominal viscera instead
• Content of the thorax: major organs of the respiratory and cardiovascular systems including conducting structures such as trachea, and esophagus. Thorax can be split into three major spaces – mediastinum and 2 lateral pulmonary cavities.
• Thoracic wall: the surrounding structure comprised of thoracic cage, the muscles that extend between its elements, skin, subcutaneous tissue and fascia. E.g. pectoralis major and serratus anterior
• Functions of thoracic wall: dome shaped and remarkably rigid but the ribs are flexible.
- Protect vital thoracic and abdominal internal organs
- Resist the negative internal pressures by elastic recoil of lung
- Provide attachment for and support upper limbs
- Provide anchoring attachment for many muscles
• Thoracic skeleton: the osteocartilaginous thoracic cage made from 12 pairs of ribs and associated costal cartilages, 12 thoracic vertebrae and IV discs, the sternum.
• Ribs: curved fat bones that form the thoracic cage. These run inferiorly as they pass to the front, reaching their lowest point at the costochondral joint in which they then ascend to sternum. There are three type of ribs:
- True ribs (costovertebral): ribs that attach directly to the sternum through their own costal cartilages (1st to 7th)
- False ribs (vertebronchal): ribs with cartilages that attach to those cartilage above them and hence indirectly attach to the sternum (8th to 10th)
- Floating ribs (vertebral): ribs with rudimentary cartilages that don’t connect to the sternum but end in the posterior abdominal musculature.
• Angle of rib: point on the rib near the posterior aspect in which it turns inferiorly and is twisted along its axis.
- The anterior angle of the rib is the weakest and most fractured location.
• Costal cartilages: linkage between ribs to the sternum and contribute to the elasticity of the thoracic wall. Cartilage of the first 10 ribs anchors the anterior end of the rib and so limit its overall movement
- Costal margin: medial edge thoracic cage formed by the inter-joining cartilage connections of the false ribs
• Intercostal space: horizontal spaces separating the ribs and their cartilages from each other and is named according to the rib forming its superior border. There are total 11 intercostal space
- Content: intercostals muscles, membrane and two sets of intercostals blood vessels and nerves.
- Subcostal: space below the 12th rib
• Sternum: flat elongated bone that forms the middle anterior part f the thoracic cage. It consists of manubrium, body and xiphoid process.
• Manubrium: widest and thickest part of the sternum.
- Suprasternal notch: the deepen concave center located at the superior border of the manubrium
- Clavicular notch: the groove in which the medial clavicular heads articulates with the manubrium (SC joint) on either side of the suprasternal notch
- Synchondrosis of the first rib: inferolateral to the Sc joint, costal cartilage of the 1st rib tightly attaches to the lateral border of the manubrium
• Body: the longer section of the sternum that is narrower and thinner than the manubrium. Its lateral borders are scalloped by the costal notches.
- Transverse ridge: synostosis of four originally separated sternebrae (segments of sternum)
• Xiphoid process: the smallest and most variable part of the sternum and lies at the level of T 10 verterbra.
• Landmark by xiphoid process:
- Xiphisternal joint: the junction of sternal body with xiphoid process marks the inferior limit of the central part of the thoracic cavity. This is also the site of infrasternal angle of inferior thoracic aperture.
- Superior limit of the liver, central tendon of the diaphragm, and inferior border of heart.
• Superior thoracic aperture: superior opening of the thoracic cage that allows communication with the neck and the upper limb. Slopes slight anteroinferiorly due to obliquity of the 1st rib
- Boundaries: posteriorly by the T1 vertebra, laterally by the 1st pair of ribs and costal cartilages, and anteriorly the superior border of the manubrium.
- Structure that passes: trachea, oesophagus, nerves, vessels that drain head, neck and upper limbs.
• Inferior thoracic aperture: inferior opening that provides a ring like origin of the diaphragm and is completed closed.
- Boundaries: posteriorly by the 12th thoracic vertebra, posteriolaterally by the 11 and 12th rib, anterolaterally by the costal cartilage of 7-10 ribs and anteriorly the xiphisternal joint.
- Structure that passes: though the demarcation of the aperture is inferior, the diaphragm that bounds it rises superiorly to the level of 4th intercostal space meaning the plane of the aperture is actually in the abdominal cavity. Structures that pass the diaphragm though are aorta, oesophagus and inferior vena cava.
• Joints of the thoracic wall: important to allow a low level of mobility to allow respiration and changes in the volume of the thoracic cavity
• Costovertebral joint: rib articulating with the vertebral column at the head of the rib and the costotransverse joints.
- Costotransverse joint: synovial plane joint articulation of tubercles of rib with transverse process of corresponding vertebra.
- Joints of head of rib: synovial plane joint where the head of each rib articulate with superior costal facet of the lower vertebrae and the inferior costal facets of the upper verterbrae (inferior and superior costal facet forms a demifacets)
• Sternocostal joint: ribs articulating with the sternum (1st to 7th only)
- 1st rib: cartilaginous joint with the manubrium of the sternum
- 2nd – 7th rib: articulates with the sternum in a plane synovial joint (2nd rib cartilages with manubriosternal joint while 7th rib cartilages with the xiphisternal joint)
• Movement of the thoracic wall: during inspiration, thoracic volume increases. The diaphragm contracts and descends compressing the abdominal viscera. Two movement of the rib cage aids this:
- Pump handle movement: the costovertebral joint for the upper ribs (2-6) allows rotation of the ribs as the transverse process forms a concave groove “wrapping” around the head of the rib. This results in the anterior ends of the ribs rising and expanding the AP dimension.
- Bucket-handle movement: costovertebral joint of the lower ribs (7th onwards) has a flat transverse process so rib head can only glide superiorly or inferiorly. And so contraction of the intercostals muscles will elevate the lateral aspect of the ribs and increase lateral dimension.
• Surface anatomy of the thoracic wall:
- Clavicles: palpable bony ridges at the junction of thorax and neck. It demarcate the superior divide between lymphatic drainage zones, i.e. above drains to inferior jugular lymph node, below flows to the axillary lymph nodes
- jugular notch: palpable between the medial ends of the clavicle at the level of the inferior border of body of T2 vertebra
- Manubrium: lies at the level of T3 and T4 vertebrae bodies. Left side is anterior to arch of aorta and right side overlies the merging of brachiocephalic vein to form SVC.
- Sternal angle: manubriosternal joint marks the level of the 2nd pair of costal cartilages and is palpable as a prominent ridge.
- Xiphoid process: lies in the depression epigastric fossa at the location of the converging costal margins (easily palpable).
- Infrasternal angle: the point at which the costal margins meet superiorly. Important location for CPR.
- Intercostal spaces: Useful to locate structures within the thoracic cage, e.g. mitral valve is most clearly heard at the 5th to 6th rib inferior to the left nipple. Counting starts at 2nd costal rib at the angle of sternum.
• Structures related to the sternal angle:
- 4th and 5th disc
- Bifurcation of the trachea into bronchi
- Concavity of the aortic arch
- Above the bifurcation of pulmonary trunk to left and right
- Azygous vein enters the SVC
- Thoracic duct reaches left side of the oesaphagus
- Ligamentum arteriosum
- Superficial and deep part of the cardiac plexus
• Surface demarcations: reference lines derived from palpable structures
- Anterior median line: intersection of the median plane with the anterior thoracic wall
- Midclavicular line: passes through mid point of clavicles
- Anterior axillary line: vertically along the anterior axillary fold (inferior border of the pectoralis major)
- Midaxillary line: runs vertically from apex of axillary fossa down
- Posterior axillary line: vertically along the posterior axillary fold formed by latissimus dorsi and teres major.
- Parasternal line: vertical line on either side of the sternum
• Muscles of the thorax:
- Pectoralis major and minor
- Serratus posterior and anterior
- Levatores costarum
- Intercostal muscles
• Serratus posterior:
- superior: extending from vertebrae (C6 – T3) to ribs (2 -5) in an inferolateral angle.
- Inferior: arises from spinous process of the lower vertebrae (T11-L2) superolaterally to the inferior border of the inferior 3 -4 ribs.
• Intercostal muscles: muscles that occupy the intercostal space and involved mainly in forced respiration. From superficial to deep, the layer of muscles are:
- external intercostal muscles
- internal intercostal muscles
- innermost intercostal muscles
• External intercostal muscles: occupy the intercostal spaces (all 11) from the tubercles of the ribs to the costochondral junction anteriorly.
- Runs anteroinferiorly from the rib above to the rib below
- Continuous with external oblique below and form membranes anteriorly
- Most active during inspiration and increase the tone of the intercostal space
• Internal intercostal muscle: 11 pairs of intercostal muscle runs deep and perpendicularly to the external intercostal muscles
- Pass from the floors of the costal groove to the superior border of the ribs below
- Continuous with internal oblique below and become membranous posteriorly
- Most active during expiration and interosseous portion depress ribs during forced respiration.
• Innermost intercostal muscles: deeper to the internal intercostal muscles and separated from it by a layer of intercostal nerves and vessels.
- Pass between internal surfaces of adjacent ribs and occupy lateral parts of the intercostals spaces
- Actions are same as the internal intercostals.
• General rule of action: muscles fibers that run in the same angle as the ribs will elevate it while fibers that run opposing angle, i.e. 90o degree out of phase will depress it.
• Fascia of thoracic wall:
- thoracic cages is lined internally with the endothoracic fascia which is attached to the parietal pleura
- between the muscles is the intermuscular fasica
- superficial fascia is beneath the skin
• Nerve innervation of the thoracic wall: 12 pairs of thoracic spinal nerve supply the wall.
- Anterior rami of T1- T11: forms the intercostal nerves that run along the intercostal space
- Posterior rami of T1-T11: pass posteriorly and supply joints, muscles and skin of the back in the thoracic region.
• Typical nerves: 3rd to 6th intercostal nerve enter the posterior intercostal spaces. Near the angle of the rib, the nerves pass between the internal and innermost intercostal muscles within the costal groove.
- collateral branches: arise near the angle of the ribs from the main intercostal nerves and descend to the superior margin of the lower rib – supply intercostal muscles and parietal pleura
- lateral cutaneous branches: arises from main nerve near the MAL and pierce the superficial intercostal muscles to supply the skin of the lateral thoracic walls
- anterior cutaneous branches: pierce and supply the skin on the anterior aspect of the thorax after branching from the main nerve at parasternal line.
• Atypical nerves:
- 1st and 2nd intercostal nerve: course on the internal surface of 1st and 2nd ribs with 1st nerve absent of anterior and lateral cutaneous branch.
- Intercostobrachial nerve: large lateral cutaneous nerve that emerge from the 2nd intercostal space to supply the floor of the axilla
- 7th to 11th intercostal nerve: after supplying the lateral cutaneous branches, the intercostal nerves become the thoracoabdominal nerves of the anterior abdominal wall and is no longer between ribs.
• Vasculature of the thoracic wall: vascular structures runs in the intercostal spaces parallel to the ribs
• Arterial supply: three main arteries branches to supply the thoracic wall:
- Thoracic aortal: supply posterior intercostal and subcostal arteries for 3rd to 11th intercostal spaces
- Subclavian artery: supply the internal thoracic and supreme intercostal arteries (1st to 2nd intercostal spaces)
- Axillary artery: supply the superior and lateral thoracic arteries
- Each intercostal space is supplied by a large posterior intercostal artery (and its collateral branch) and a small anterior intercostal arteries.
• Posterior intercostals: courses between internal and inner most intercostal muscles and supply the intercostal muscles, overlying skin and parietal pleura.
- right arteries cross the vertebrae and pass posterior to esophagus, thoracic duct and azgos vein and pleura
- gives rise to a small collateral branch that cross the intercostal space and run along the superior border of the lower rib
- follows course of intercostal nerve and pass below vein and above nerve
- have terminal and collateral branches anastomosing with anterior intercostal arteries
• Anterior intercostal: course and supply opposite to posterior intercostal, i.e. anterior instead of posterior. The first 6 arteries are derived from internal thoracic and last 3 derived from musculophrenic arteries.
- Pass both inferior to upper rib and superior to lower rib
- Supply the intercostal muscles and send branches to pectoral muscle, breast and skin
- Absent from inferior two intercostal spaces (which is supplied by posterior intercostal)
• Internal thoracic: descends into the thorax posterior to the clavicle and 1st costal cartilage
- Terminates in the 6th intercostal space by dividing into superior epigastric and musculophrenic arteries
- Directly give rise to anterior intercostal arteries
• Breast: mammary glands accessory to women but rudimentary in men. Located in the subcutaneous tissue overlying the pectoralis major and minor. Mammary glands are modified sweat glands
- Dimensions: extends transversely from lateral border of sternum to midaxillary line and vertically 2nd to 6th ribs.
- Retromammary space: bursa between the breast and pectoral fascia with small amount of fat to allow some movement of the breast.
- Axillary process: a small part of the breast that extends to the axillary fossa along the inferolateral edge of the pectoralis major
- Suspensory ligaments: substantial skin ligaments that attaches the breast firmly to the dermis of the overlying skin.
- Lactiferous ducts: ducts that drains the lobules (15 – 20) of the glandular tissue
- Lactiferous sinus: dilated portion of the duct deep to the areola that houses accumulated milk
• Arterial supply of breast:
- Medial mammary branches of perforating branches and anterior intercostals artery
- Lateral thoracic and thoracoacromial arteries of axillary artery
- Internal thoracic arteries
- Posterior intercostals arteries
• Lymph drainage of breast:
- Majority of lymph drains into axillary lymph nodes, initially pectoral nodes
- Remaining lymph drains to parasternal lymph nodes or deep to abdominal lymph nodes
- Sequence: axillary nodes into clavicular (infra/supra) lymph nodes and into subclavian lymphatic trunk; lymph from parasternal nodes enters bronchomediastinal lymphatic trunks; along with the jugular lymphatic trunk, all these form the right lymphatic duct which will drain into the thoracic duct
• Pleura tap: removal of air that resides in the intrapleural cavity (e.g. pneumothorax). Placement is at 5th intercostal space at the mid axillary line.
- Sequences: 3 cm incision below space, dissection into pleural space, insert drain (high for pneumo, low for haemo) and place underwater seal
- Structure passed: skin, subcutaneous, deep fascia, serratus anterior, external/internal/innermost costal muscle OR transverse costal muscle, endothoracic fascia (break sound indicative of reaching cavity), parietal pleura, pleura cavity, visceral pleura, lung

Lecture 5: Ventilation (action of muscles)

• Involvement of muscles: only muscles that present electromyographic evidence during respiration are classified as respiratory muscles.
• Features of resting lung: sits a FRC with the lung slightly stretched and the thoracic cage slightly compressed. Volume change in either direction will cause change in energy of muscle action.
• Resistance of the lung:
- Elastic recoil of the lung
- Frictional resistance of the tissue
- Frictional resistance to airflow
- Examples: high resistance with fibrosis (excessive collagen) and low resistance with emphysema
• Muscles of inspiration:
- Diaphragm
- Scalene
- Intercostals
• Features of diaphragm: musculofascial sheet of tissue
- Central portion of diaphragm is fascia
- IVC (at center tendon) and aorta (retro) does not pass through muscle so contraction does not compress lumen
- Band of muscle called right crus wrap around the oesophagus
- Costal margin form attachment point of the diaphragm
- Innervated by the phrenic nerve from cervical levels (embryonic development reasons)
• Costodiaphragmatic recess: the space in the pleural cavity at the edge of the diaphragm. Fluid effusion causes fluid to accumulate in that position and hence needle is inserted there to drain.
• Inspiration:
- Diaphragm: quiet breathing causes 1.5 cm movement of the diaphragm producing tidal volume of 350-500mL. Deep breathing causes a 10cm movement.
- Scalene: 3 muscle fibers (ant, mid, pos) arise from the transverse processes of the cervical vertebrae and insert onto the upper two ribs. Produce pump-handle movement of ribs in forced inspiration (asthmatic utilize scalene – a diagnostic factor).
- Intercostals: external muscles act to raise the ribs in a bucket handle motion. During quiet breathing, the upper 3-4 interspaces are active. With increasing depth of breathing, lower interspaces are progressively recruited.
• Rib movements:
- Pump handle: axis of movement is along the transverse process allowed rotation of the rib in the axis
- Bucket handle: axis of movement is deviated so rotation is not possible but instead limited to sliding
• Accessory muscles of ventilation:
- Sternocleidomastoid: runs parallel to scalene to aid elevation of ribs and sternum
- Quadratus lumborum: assist diaphragm depression and pulls down 12th rib
- Serratus posterior superior: elevate ribs (traditional view)
- Serratus posterior inferior: depress ribs (traditional view)
- Levators costarum: elevate the ribs and allow ribs to swing outwards and forwards
• Expiration: both passive (elastic recoil and relaxation of muscle) and active processes (muscle contraction)
- Diaphragm: braking effect
- Quadrates lumborum: slow down rise of 12th rib and diaphragm
- Internal intercostals: lower 3-4 interspaces used first and progressively recruit superior intercostals with increase depth of breathing.
- Transverses thoracis: active ventilator running from rib to sternum and can pull the ribs down
- Abdominal muscles: compress abdominal cavity and antagonist of diaphragm, i.e. push diaphragm upwards

Lecture 11: Pleura, bronchi and lungs

• Pulmonary cavities: bilateral compartments containing the lung and pleurae.
• Pleura: serous sac that envelops the lung forming two continuous membranes of visceral pleura that lines the surface of the lung and parietal pleura that lines the pulmonary cavities.
- visualization: the lung is fisted into a balloon like sac with reflections of the membranes where the bronchi enters the lung (hilum)
• Parietal pleura: serous lining of the pulmonary cavity consisting of four parts:
- Costal part: covers internal surface of thoracic wall
- Mediastinal part: covers lateral aspects of the mediastinum and reflects to become the visceral pleura
- Diaphragmatic part: covers the superior surface of the diaphragm except where the diaphragm fuse with the pericardium
- Cervical pleura: extends through the superior thoracic aperture forming a cup shaped dome over the apex.
• Pulmonary ligament: the empty double layer of pleura inferior to the root of the lung extending between the lung and the mediastinum.
• Suprapleural membrane: a fibrous extension of the endothoracic fascia that attaches to the internal border of the 1s rib and transverse process of C7 vertebra.
• Pulmonary recesses: spaces inside the pleural cavity in which the lung does not occupy. The inferior borders of the lung move into the recesses during deep inspiration and retreat during expiration
- Costodiaphragmatic recess: gutters formed at the edge of the convex diaphragm.
- Costomediastinal recess: smaller spaces located posterior to the sternum where the costal pleura is potentially in contact with the mediastinal pleura
- Retroesophageal recess: small space posterior to the esophagus.
• Pleural reflections:
- 2nd rib: right and left pleura comes in contact
- 4th rib: left pleura passes laterally due to cardiac notch
- 6th rib: both pleura passes laterally
- 8th rib: pleura reaches MDL
- 10th rib: pleura reaches MAL
- 12th rib: pleural reaches the posterior vertebrate
• Lungs: organ of respiration and main function is to oxygenate venous blood.
- Hilum: the area in which the structures forming the root enter and leave the lung
- Horizontal fissure/oblique fissures: deep sharp grooves that divides the lung into lobes. Right lung has both fissure thus three lobes but left has only oblique so two lobes.
- Cardiac notch: deep indentation on the anterior border of the left lung by the heart due its left deviation (located below 4th rib lateral to sternum)
- `
- +Lingual: thin tongue like process of the superior lobe that extends below the cardiac notch anteriorly in and out of the costomediastinal recess (located at 6th rib)
• Surface marking of fissure:
- medial margin of the scapula marks roughly the course of the oblique fissure with T4 spine as the medial demarcation
- horizontal fissure rest roughly between rib V and rib VI
• Root of the lung: structures that enters through the uncovered opening of the pleura to reach the lung. Structure involved:
- Pulmonary artery located superoanteriorly
- Superior and inferior pulmonary veins located inferoanteriorly
- Bronchus located middle of the posterior boundary with bronchial vessels surrounding it
• Pleural sleeve: double layer of pleura (parietal and visceral) that enclose the circumference of the root of lung
• Surfaces of the lung:
- costal surface: large smooth and convex and referred to as the vertebral part of the costal surface
- mediastinal surface: concave to accommodate the heart and adjacent vessels and include hilum and root of lung.
- Diaphragmatic surface: concave and rests on the dome of the diaphragms. Concavity is deeper in the right lung due to higher position of the right dome (over the right liver).
• Grooves of lung surface:
- Right surface: groove for SVC/IVC (near middle), azygos (same place as oblique fissure), oesophagus (posterior to hilum), cardiac impression (anterior to hilum)
- Left surface: groove for left subclavian artery (over apex), descending aorta (posterior to hilum), cardiac notch/impression (anterior to hilum)
• Borders of the lung:
- Anterior border: costal and mediastinal surface meet anteriorly and overlap the heart
- Inferior border: circumscribes the diaphragmatic surface of lung
- Posterior border: costal and mediastinal surface meet posteriorly with a broad and rounded edge
• Trachea: conducting passage of air located in the superior mediastinum and supported by c-shaped rings of hyaline cartilage and delivers into the bronchi.
- Bifurcates at sterna angel into two main bronchi, one to each lung.
• Bronchi: continued conducting airway from the trachea that delivers gas into/out of the hilum of the lung
- Right main bronchus: wider, shorter and more vertically
- Left main bronchus: passes inferolaterally inferior to arch of aorta, anterior to esophagus
• Bronchopulmonary segments: pyramidal shaped segments of the lung separated by connective tissue. These are the largest sub-division of a lobe and is surgical resectable.
- Objects that passes into the lung are likely to fall in to the superior bronchopulmonary segment of the right inferior lobe
• Lobes of the right lung:
- Upper: apical, posterior, anterior
- Middle: medial, lateral
- Lower: superior, anterior basal, medial basal, posterior basal
• Lobes of the left lung:
- Upper: apical anterior, posterior, inferior, superior
- Lower: superior, anterior basal, posterior basal, lateral basal, medial basal
• Surface marking of lung lobes: superior lobe at top of pectoral region, middle lobe at nipple, inferior lobe beneath the pectoral laterally, apex of lung at medial clavicle
• Pulmonary supply of blood:
- Pulmonary arteries: arise from the pulmonary trunk at level of sternal angle. Gives off its first branch to superior lobe before entering the hilum
- Bronchial arteries: supply blood for nutrition of structures. Two left bronchial usually arise directly from thoracic aorta and single right bronchial from ascending aorta. Bronchial artery pass along the posterior aspect of main bronchi and branches, reaching as distal as the respiratory bronchioles
- Segmental branches: supply the bronchopulmonary segments
• Pulmonary drainage of blood:
- Pulmonary veins: two veins for each lung carrying well-oxygenated blood. Begins at the pulmonary capillaries, the vein unite into larger and larger vessels.
- Bronchial veins: drain only the lung supplied by the bronchial arteries. Right bronchial vein pass into the azygos vein and left bronchial vein drains into the accessory hemiazygos vein.
• Organization of vasculature:
- bronchi and pulmonary arteries are paired and branch in unison with the pulmonary arteries coursing around the bronchi
- intrasegmental pulmonary artery pass into the walls of the alveolar sacs and alveoli where gas exchange occurs
- pulmonary veins arise from capillaries drain towards and course within septa between adjacent segments independent of the artery and bronchi.
• Lymphatic plexus of lung:
- Superficial lymphatic plexus: drains the lung parenchyma and visceral pleura. Later pass into the bronchopulmonary lymph nodes.
- Deep lymphatic plexus: located in the submucosa of bronchi and draining structures of the root of the lung. Lymph later pass to pulmonary lymph nodes
- Superior/inferior tracheobronchial lymph nodes: deep and superficial plexus drains into these and they are located respectively superior and inferior to bifurcation of the trachea.
- Right/left bronchomediastinal lymph trunks: final destination of lymph drainage before converging into right lymphatic duct (right) and thoracic duct (left)
• Nerve innervation of lungs: supplied mainly by the pulmonary plexuses containing parasympathetic vagus nerves and sympathetic fibers of the sympathetic trunk.
- Parasympathetic functions: bronchoconstriction, vasodilator, secretomotor (mucus). Preganglionic fibers pass from brain stem to lung parenchyma and short post sympathetic fibers innervate the tissue.
- Sympathetic functions: bronchodilator, vasoconstrictor, inhibition of secretion. Preganglionic nerve passes from lateral horn to paravertebral ganglion, and postganglionic pass to lung tissue
- Afferents: pain sensation and cough reflex travel to brain stem with the preganglionic parasympathetic fibers of the vagus nerve
• Pathways of sympathetic nerves: sympathetic fibers initiate from the lateral horn pass to the dorsal root. From here they can:
- Travel up the sympathetic chain to eyes
- Travel from the sympathetic chain to the heart
- Travel from the sympathetic chain to prevertebral ganglia and innervate the GI organs
• Intercostals nerves: supplies the costal pleura and diaphragmatic pleura
• Phrenic nerves: mediate sensation of touch and pain and located in the central part of the diaphragmatic pleura

Lecture 12: Radiology of the Thorax I

• Injuries to the pleura:
- Pneumothorax: puncturing of parietal pleura allows air to enter the pleural cavity and compromising surface tension and the lung collapses
- Haemothorax: injury causing blood to enter the pleural cavity
• Common features:
- Fluid seen in the costodiaphragmatic recess at the posterior thoracic wall
• Pleura problems:
- Pneumothorax
- Pleural effusion
- Tumours
• Pneumothorax:
- Air pass into the pleural cavity shows a large black area (visceral pleura popped)
- Lack of lung marking on the outside, i.e. bronchi and vessel absent at the periphery
• Fluid effusion: too much pressure in pulmonary vasculature and fluid is pushed into the intrapleural cavity and accumulates. Can occur with pneumonia where inflammation causes fluid effusion unilaterally
- shifting of the mediastinum
- White out on one side indicative of rupture of pulmonary vein or metastatic cancer from breast (tumour secrete fluid)
- Meniscus effect in the pleura space
- Example: congestive heart failure.
- Small pleura effusion: will prevent reaching meniscus
- White markings shows you fluid
- No meniscus is possible as the lung inflate on top on the project
• Car accident: chest trauma with widening of the mediastium.
- Descending aorta have majority of blood contained in the 3rd layer but can accumulate in between 1st and 3rd space.
• Pleura calcification: extreme white well defined nodules indicates calcification
• Tumours:
- Mesothelioma: extreme case where one side of the thoracic cavity is completely white out by mesothelioma (a very large possibly).
- Procedure of observation: mediastinum, pleura, lungs and chest wall
- Intrapleural tumour: forms an acute angle between lesions and pleura in the lung with the wall as the base, the margin will be fuzzy as it is lined with alveoli
- Extrapleural tumour: tumour forms an obtuse angle between lesions and pleura in the lung with sharp margin lined with visceral pleura
- Lymphoma: large and white mediastinum
• Chest wall disorder:
- Rib erosion: darkening of the rib
- Osteosarcomma: extended whiteness of the rib (expanded)

Lecture 14: Summary of lymphatics, nerves of thorax, diaphragm

• Diaphragm: double domed musculotendinous partition separating the thoracic and abdominal cavities (convex into the thoracic cavity).
- Main muscle of inspiration
- Pericardium at the center of the diaphragm depress it slightly
• Dome of the diaphragm: diaphragm curves superiorly into right and left domes. The right dome is usually higher due to the liver, i.e. during expiration, right dome reaches 5th rib but left only 5th intercostal space. Dome level varies according to:
- Phase of inspiration
- Posture
- Size of abdominal viscera
• Central tendon: the central aponeurosis in which all the muscular fibers of the diaphragm converge toward from the periphery. It has no bony attachment and roughly divided into three leaves.
• Muscles of the diaphragm: continuous sheet divided into three parts:
- Sternal part: consisting of two muscular slips attached to the posterior aspect of the xiphoid process
- Costal part: wide muscular slips that attach to the internal surfaces of the inferior six costal cartilages and their ribs forming the left and right dome
- Lumbar part: arise from the medial and lateral arcuate ligament and three superior lumbar vertebrae, the lumbar parts forms right and left muscular crura (crus) that ascend to the central tendon.
• Crus of diaphragm: musculotendinous bundles arise from the anterior surface of the superior three lumbar vertebrae, anterior longitudinal ligament and IV discs.
- Right crus: fibers forming the right of the aortic hiatus and is larger and longer than left crus
- Left crus: fibers forming the left of the aortic hiatus
• Median arcuate ligament: ligaments that arches over the anterior aspect of the aorta as part of the aortic hiatus
• Medial/lateral arcuate ligament: thickenings of the fascia covering the psoas major with medial spanning between lumbar to tip of the transverse process of L1) and lateral spanning between L12 transverse process to tip of 12th rib covering the quadratus lumborum .
• Diaphragmatic apertures: 3 major opening within the diaphragm that allows structure to pass from the thorax to the abdomen.
• Caval opening: opening in the central tendon for the IVC. Other structures include terminal right phrenic and lymph vessels.
- Location: junction of the tendon’s right and middle leaves (right of the median plane) at T8
- Action: as the IVC adhere to the margin of the caval opening, when diaphragm contracts (inspiration), it widens the opening and dilates the IVC facilitating blood flow to the heart.
• Esophageal hiatus: oval opening for the esophagus in the muscle of the right crus. Other structures are anterior and posterior vagal trunk, branches of left gastric vessels and lymph vessels.
- Location: T10 level posterior left to the caval opening
- Action: the right cus decussate to the left inferior to the hiatus, forming a sphincter that constrict it when diaphragm contracts
• Aortic hiatus: opening for the aorta posterior to the diaphragm. The aorta does not pierce the diaphragm so blood flow is not affected by respiration. Also transmit the thoracic duct and sometimes azygos/hemiazygos veins
- Location: between crura of the diaphragm posterior to the median arcuate ligament at the level of T12
• Sternocostal triangle: opening between sternal and costal attachment of the diaphragm in which the epigastric vessel and lymphatic pass,
• Postures on diaphragm:
- Supine posture: diaphragm most superiorly located, and abdominal viscera push the diaphragm superiorly in the cavity
- Lies on one side: the hemidiaphragm rise to a more superiorly level because of greater push on one side
- Upright: diaphragm at a lower level, hence people with dyspnea prefer to be upright to increase non-tidal lung volume and diaphragm works with gravity
• Arterial supply of the diaphragm: branching pattern of the arteries supply the superior and inferior surfaces.
- Superior surface: pericardiacophrenic and musculophrenic arteries around the pericardium, (branch of internal thoracic); superior phrenic arteries (branch of the thoracic aorta)
- Inferior surface: inferior phrenic arteries (branch of the abdominal aorta) spreading out radially
• Nerve innervation of the diaphragm: motor supply is by the right and left phrenic nerves that arise from the anterior rami of the C3-C5 segments. These are also the sensory fibers.
- periphery of the diaphragm receive their sensory nerve supply from the intercostal nerves
- branches of the phrenic nerve spreads out radially hence surgical incisions can not be made circularly
• Lymph drainage of thorax: three main pathway of drainage
- Tracheobronchial node can drain either bronchomediastinal nodes or right lymphatic duct
- Diaphragmatic nodes can drain either to the middle or anterior pathway
- Anterior: diaphragmatic nodes -> parasternal -> brachiocephalic node -> tracheobronchial node
- Middle: diaphragmatic nodes -> posterior mediastinal node -> tracheobronchial node
- Posterior: posterior intercostal nodes -> right lymphatic duct (posterior intercostal also form communication with thoracic duct)

Lecture 18: Radiology of the Thorax II

• Lung diseases: capable of affecting a range of areas within itself.
- Pulmonary arteries: pulmonary emboli (can be clots that dislodge from other parts of the body), vasculitis
- Bronchi: asthma, bronchitis
- Lung parenchyma: pneumonia, cancer (primary or metastasize), emphysema etc
- Others: congenital cardiac failure
• Distinguishing of lung disease:
- History
- Distribution of disease
- Nodes, effusion, cardiac size
- Presentation
• Lymphoma: large whitening of the mediastinum
• Lung cancer: tumour (white mass) appears to burrow out of the rib and into the lung following the path of least resistance.
• Differentiation of pneumonia and cancer:
- Cancer: pain, haemophysis, weight loss. Well defined outline of the white mass without pattern of containment.
- Pneumonia: fever and cough. Edge of the whiteness (effusion) will be usually along the edge of the fissures (seen as a sharp edge).
• Bacterial infection: puffy, fussy white mass
• Acute pulmonary emboli:
- Usually not shown with the chest X-ray
- Signs of breathlessness (very general)
- Blood test can help confirmation
• Focal: commonly due to infection or tumour.
- Clinical presentations are important in identification
• Signs of focal diseases:
- Calcification: very white and dense solitary nodule (can’t be cancer as cancer have no calcification that occupy entire tumour)
- Tuberculosis: small center of granulation in early stages (small white mass)
• Signs of multifocal disease:
- SARS: viral infection with scattered dots
- Tuberculosis: multi nodal representation. Very characteristic occupying the upper lobe. The lower lobe is unfit for colonization due to the rich supply of vasculature (i.e. bacteria is cleared away)
- Lymphadenopathy: para-trachea mass (large white mass) showing enlargement of mediastinal lymph nodes
• Diffuse lung abnormality
- Drowning: complete white out of the pleura space as it is filled with liquid
- Congestive heart failure: cardiomegaly and pleural effusion from vessels, e.g. pulmonary edema.
- Tuberculosis: later stage scarring of the tissue distributed along the upper lobe shown as puffy white masses
- Emphysema: destroyed lung tissue
- Pneumonia: pus
- Usual interstitial pneumonia: idiopathic pulmonary fibrosis with patients getting progressively unwell as lung shrinks. Fibrosis of the lung forms holes resembling that of honey comb. Biopsy of tissue may cause pneumothorax
• Distribution of diffuse lung disease:
- Upper lobe: tuberculosis, radiation, silicosis (Miner’s disease), sarcoidosis
- Lower lobe: lymphangitic metastases, asbestosis (fibrosis due to exposure to asbestos), UIP
- Anywhere: metastases
• Collapse of lung lobe: Collapse of the upper lobe goes forward pulling the pulmonary artery downward – possibly due to blockage of bronchi by tumour and not letting air pass through
- Collapse of lobe can be due to either cancer or pneumonia depending on the history and the symptom presented.
• Connective tissue disease associated with lung disease:
- Rheumatoid arthritis
- Progressive system schlerosis
- System lupus erythematoisis
- Dermatomyositis/polymyositis
- Sjogren’s syndrome
- Lymphangitic carcinomatosis: CT appearance of thickened septal lines (irregular polygon) due to tumour in the lympathics venules and in the walls of the bronchopulmonary lobules. White divisions are tumours. Located usually in breast, colon, lung, stomach etc and associated with a primary cancer

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License