Which ribs are connected to the sternum and how?
-ribs 1-7 by costal cartilage (true ribs)
How are ribs 8-12 connected?
- Ribs 8-10 are connected to costal cartilage above
- Ribs 11-12 are floating ribs -> end free in abdo muscles
Where is the costal margin?
-The arch made by ribs 8-12
Which ribs are considered typical? Describe them
- 3-9
- Two articular facets on the head
- Tubercle on the inferior neck
- Costal groove runs along inferior surface
Describe rib 1
-Shortest, broadest and most curved with single facet at head
Describe ribs 11 and 12
- Single facet on head
- No tubercle
- Tapering end
What are the two costovertebral joints?
- Joint of the head of the rib (articulates with same level vertebrae and superior)
- Costo-transverse joint
In which direction do the upper ribs move?
-Anterio-posterior (increase saggital diameter)
In which direction do the lower ribs move?
-To increase transverse diameter
How many muscles does each intercostal space contain? Name them
- 3
- Innermost
- Internal
- External
Which way do the external intercostal muscle fibres run? What does contraction of these muscles cause?
- Downwards and anterior
- Elevation of ribs
Which way do the internal intercostal muscle fibres run? What does contraction of these muscles cause?
- Downwards and posteriorly
- Pull down the ribs during forced expiration
Which way do the innermost intercostal muscle fibres run? where do they lie? What does contraction of these muscles cause?
- Downwards and posterior
- Lie laterally
- Depression of ribs during forced expiration
Do the intercostal muscle go from spine to sternum?
-No the internal end before the spine and the external end close to costal cartilage
What runs in the costal groove?
-Neurovascular bundle (runs between internal and innermost) (Collaterals at upper border)
What nerves run in the costal grooves? What do they serve?
- Anterior rami of thoracic spinal nerves t1-t12
- Intercostal muscles, parietal pleura and overlying skin
Where does the posterior intercostal artery arise from?
-Abdominal aorta
Where does the anterior intercostal artery arise from?
-Internal thoracic artery which arises from subclavian
Where does the venous drainage from the thoracic wall go?
- Azygous system -> SVC
- Some into internal thoracic vein
Where do the muscle fibres of the diaphragm insert?
-Central Tendon
What happens during contraction of the diaphragm?
-Descent of diaphragm accounting for 70% of chest expansion in quiet respiration
What are the openings in the diaphragm?
- T8-vena cava
- T10 -> Oesophagus
- T12 -> Aortic haitus (aorta)
How does the pleura relate to the diaphragm?
-Surrounds the upper convexity
Describe the relationship between the lungs and the liver
-The liver extends upto 5th rib and is overlapped by the lungs and pleura
Describe the surface anatomy of domes of the diaphragm during expiration
- Right dome 5th rib MCL
- Left dome 5th ICS MCL
Describe the nerve supply of the diaphragm
-Phrenic nerve (C3C4C5)
Describe sensory innervation of phrenic nerve
- Pericardium
- Diaphragm
- Mediastinal parietal pleura
What muscles are involved in quiet inspiration?
- External intercostals
- Diaphragm
What muscles are involved in forced inspiration?
- Pec major
- Serratus anterior
- scalene
- Sternocleidomastoid
Why might someone lock their arms in order to breath?
-Fixing the arms makes pec major solely expand chest
What muscles are involved in quiet expiration?
-None, it is passive using elastic recoil of the chest wall and lungs
What muscles are involved in forced expiration?
- Internal and innermost intercostals
- Anterior abdominal muscles
Name the 4 parts of the parietal pleura
- Cervical
- Mediastinal
- Costal
- Diaphragmatic
What is the pleural seal?
- film of fluid covers the pleural surfaces
- surface tension between these molecules resists the surfaces being pulled apart thus when the thorax expands the visceral pleura and lung expand with it
What is the costodiaphragmatic recess?
-Pleural lined gutter which surrounds the upwards convexity of the diaphragm which is not occupied by lung
State the margins of the trachea
- Lower border of cricoid cartilage
- Division of right and left main bronchi at carina (t4/t5)
Where is the trachialis muscle?
-Posterior of trachea
Why might a carina be widened?
-enlarged tracheo-bronchial nodes
Why are you more likely to aspirate into right bronchi?
-Straight line so easily accessible
How many lobar bronchi on the left and right?
- 3 on right (Upper middle and lower) (3 lobes)
- 2 on left (upper and lower) (2 lobes)
What do lobar bronchi split into?
-Segmental bronchi
What is a bronchopulmonary segment? Why is this beneficial?
- An area of lung supplied by its own segmental bronchus and segmental branches of pulmonary artery and vein
- Surgically significant as a segment can be removed without damage to others
Describe the right lung
-3 Lobes separated by horizontal and oblique fissure
Describe the left lung
- 2 Lobes separated by an oblique fissure
- Lingula is an area on the left upper lobe which corresponds to the right middle lobe
What is the clinical significant of the apex of the lung extending into the root of the neck?
- Apical lung tumours may involve structures in the root of the neck eg brachial plexus (esp. medial cord), subclavian vessels or sympathetic trunk
- Subclavian vein cannulation may damage lung -> pneumothorax
What is the hilum of the lung?
-Indentation where pulmonary vessels, main bronchus, nerves and lymphatics enter and leave the lung
Describe the anterior, middle and posterior areas of mediastinum
- All from thoracic inlet to lower border of T4
- Anterior between sternum and pericardium
- Posterior between verterbral bodies and pericardium
- Middle in between
Describe the surface markings of the pleura
- From apex down behind sternoclavicular joint to meet each other near midline behind sternal angle
- Passes down to 4th rib
- Right continues down to 6
- left deviates laterally to edge of sternum then down to 6th rib
- Both then deviate laterally to rib 8 MCL
- then 10 mid axillary line
- then 12 medial scapular
Describe the surface markings of the lungs
- Follows pleura to rib 6 where it goes to MCL
- Rib 8 mid axillary line
- Rib 10 scapular line
What three areas make the sternum?
- Manubrium
- Body
- Xiphoid process