Anatomy - Thorax Flashcards
Which parts of the rib articulate with the vertabrae?
Head - vertebral body above and below forming the costovertebral joint
Tubercle - transverse process forming the costo-transverse joint
Which ligamentous structure supports the opening in the diaphragm through which the aorta passes?
Right and left crura giving rise to the median arcuate ligament
How are the extenal intercostal muscles involved in inspiration?
Contraction leads to upward and outward movement of the anterior chest wall
What are the muscles of inspiration?
Extenal intercostal muscles
Scalene muscles
What are the muscles of expiration?
Internal intercostal muscles
Abdominal wall muscles
What are the main branches of the arch of the aorta?
Brachiocephalic trunk
Left common carotid
Left subclavian
Which branches are given off in the first part of the subclavian artery?
Vertebral artery
Internal thoracic
Thyrocervical trunk
Remember: VIT C & D
Part 2: Costocervical trunk
Part 3: Dorsal scapula
Which veins form the brachicephalic vein?
Subclavian and inernal jugular vein
Which structure spearates the subclavian artery from the subclavian vein?
Saclenus anterior mucle
- Subclavian artery behind (with brachial plexus)
- Subclavian vein infront (with phrenic nerve)
Which structures form the superior vena cava?
Right (short) and left (long) brachiocephalic vein
Which structure arches over the right main brunchus?
Azygous vein
How does the drainage of the azygous veins operate?
Right chest wall drained by intercostal veins directly into azygos vein
Left chest wall drained by two hemiazygos veins which then drain into the azygos vein
The azygos vein drains into the posterior aspect of the superior vena cava
Pathway of the phrenic nerve in the neck
Runs infront of the scaelnus anterior muscle and subcian artery
Runs posterior to the subclavian vein
Pathway of the vagus nerve in the neck
Runs infront of the common carotid artery and subclavian artery
Runs behind the internal jugular vein
Where is the recurrent laryngeal nerve branches given off?
Right - beneath the subclavian artery
Left - beneath the arch of the aorta
How are the phrenic and vagus nerves ralted to the hilum of the lung?
Phrenic - infront
Vagus - behind
What is the anatomical boundaries of the breast?
Rib 2-6
Sternum - mid-axillary line
Describe the lactiferous duct system
Each breast has 15-20 lobules separated by ligaments of Cooper
Each lobule is drained by a lactiferous duct into the lactiferous sinus beneath the areola
Lactifeous sinus acts as a reservoir
Lymphatic drainage: breast
Axillary >75%
Parasternal 10-25%
Posterior intercostal 5%
What are the 3 levels of lymph node staging for breast cancer?
Level 1 - nodes lateral to Pec minor
Level 2 - nodes beneath Pec minor
Level 3 - nodes medial to Pec minor
What are the deep relations to the breast?
Pec major 2/3
Serratus ant 1/3
What are the main constituents of breast tissue?
Fat, fibrous and glandular tissues
What are Cooper’s ligaments of the breast?
AKA Suspensory ligaments
Fibrous septa which extend from subcutaneous tissue to the pectoral fascia, separating the breast lobules
Blood supply: Breast
- Internal thoracic (1st Part of Subclavian artery)
- Lateral thoracic (2nd part of Axillary artery)
- Thoraco-acromial (2nd part of Axillary artery)
- Intercostal arteries via perforating branches
Where do the right and left crus of the diaphragm attach?
Right - L3 vertabrae
Left L2 vertabrae
Attachement: diapgragm
xiphoid process, lower 6 ribs, sternum, lumbar vertabrae
Contents of the anterior mediastinum
Thymus
Internal thoracic artery
Lymphatics
Contents of the middle mediastinum
Heart
Aorta (ascending)
SVC
Main bronchus
Pulmonary artery & vein
Phrenic nerve
Lymphatics
Contents of the posterior mediastinum
Descending aorta
Azygos & hemiazygos vein
Vagus nerve
Thoracic duct
Oesophagus
Lymphatics
What are the layers pierced when inserting a subclavian line?
- Skin
- Platysma
- Fascia
- Pectoralis major
- Subclavius
- Subclavian vein
What is the anatomical landmarks for insertion of the subclavian line?
Needle inserted 1cm below the junction between the middle and medial thirds of the clavicle
Directing the needle medially, slightly cephalad and posteriorly toward the suprasternal notch
Where should the catheter tip of a subclavian line sit?
Within the SVC above the pericardial reflection
What structures are at risk during subclavian line insertion?
- Subclavian artery - haemothorax
- Pleura - pneumothorax
- Thoracic duct (left) - chylothorax
- Phrenic nerve as it runs posteriorly
Where does the apex of the pleura project?
2.5cm above the junction between the medial and middle thirds of the clavicle
What is the nerve supply to the parietal and visceral pleura?
Parietal - intercostal nerves and phrenic nerve
Visceral - pulmonary plexus (formed from branches of the vagus and sympathetic trunk)
What anatomical line separated the superior and inferior mediastinum?
Angle of Louis
- Rib 2
- T4/
Contents of the superior mediastinum
From anterior to posterior
1. Thymus
2. Great veins
3. Great arteries
4. Trachea
5. Oesophagus
Role of the thymus gland
Specialised immune organ - active before birth and atrophies after puberty
Involved in maturation of T-cells, desctruction of autoimmune T-cells and immune regulation of T-cells
How are ribs 1 and 2 atypical?
Rib 1 - short & wide, single facet, scalene tubercle on inner border
Rib 2 - thin & long, superior tuberosity for serratus anterior
How are ribs 10,11,12 atypical?
Rib 10 - single facet articulating with T10
Rib 11 & 12 - floating, single facet, no neck
Inferior border of the heart
5th intercostal space mid-clavicular line to the 6th costal cartilage at the right parasternal edge
Superior border of the heart
3rd costal cartilage at the right parasternal edge to the 2nd intercostal space 2cm left of the sternum
What forms the majority of the anterior surface of the heart?
Right Ventricle
What forms the posterior aspect of the heart?
Left Atrium
Name the layers of the pericardium
Fibrous pericardium (attached to the central tendon of the diaphragm)
Parietal serous pericardium
Visceral serous pericardium
What is the normal SNA firing rate?
Natural pacemaker at 100-120 bpm
Slowed to resting by parasympathetic stimulation
What is the blood supply of the SAN?
60% RCA
40% LCA
Where is the SAN located?
In the crista terminalis of the Right Atrium
Describe the venous drainage of the heart
2/3 drained by veins that drain into the coronary sinus and subsequently into the right atrium (inferior part between IVC and tricuspid valve)
These veins are the great, middle, small, oblique and posterior
The remaining 1/3 is drained by venae cordis minimae which drain directly into each chamber
There are also 3-4 anterior cardiac veins which drain directly into the RA
Where does the coronary sinus open?
Inferior part of the RA, between the IVC and tricuspid valve
Surface anatomy of the pleura
Apex - 2.5cm above the junction between the medial and middle thirds of the clavicle
Descends behind each sternoclavicular joint to meet at the midline at the level of rib2
Continues down to 6th costal cartilage on the right and 4th on the left (to accommodate the heart)
On both sides, pleura crosses 8th rib in MCL, 10th rib MAL and 12th rib posteriorly (at lateral border of erector spinae)
How does the surface anatomy of the lungs differ to the pleura?
Same superiorly, differs at inferior border
Lung lies 2 spaces above pleura
Pleura - 8th rib in MCL, 10th rib MAL and 12th rib posteriorly
Lung - 6th rib in MCL, 8th rib MAL and 10th rib posteriorly
Surface anatomy: oblique fissure
Line drawn obliquely downwards and outwards from 2.5cm lateral to the spine of T3 along the 5th ICS to the 6th costal cartilage approximately 5 cm from the midline
Surface anatomy: horizontal fissure
Only present on the right
Runs from the edge of the 4th costal cartilage to the oblique fissure where it crosses the 5th rib
Vertebral level: suprasternal notch
T2/3
Vertebral level: angle of louis
T4/5
Vertebral level: xiphisternum
T9
How does the right phrenic nerve descend in the thorax?
Initially right of the brachiocephalic vein, then SVC, RA and IVC with which it transverses the diaphragm at T8
How does the left phrenic nerve descend in the thorax?
Initially left of the left subclavian artery, aortic arch, LV then pierces the diaphragm on its own
How do the vagus nerves descend?
Exit the skull via the jugular foramen
Descends neck in the carotid sheath
Travels posterior to lung hilum
Forms plexus around oesophagus (right posteriorly and left anteriorly)
Vertebral level : trachea beginning
C6
Vertebral level : Carina
T4/5 Angle of Louis
Which bronchus is at high risk of occlusion by foreign body?
Right - more vertical, shorter and wider
Describe how each bronchopulmonary segment of the lung operates
Functionally independent area separated by connective tissue, with its own segmental bronchus, artery, vein and lymphatics
There are around 10 in each lung
What structures make up the lung hilum?
Pulmonary arteries and veins
Main bronchus
Bronchial arteries and veins
Lymph nodes
Autonomic nerves
Where is needle compression of a tension pneumothorax performed?
Old guidance - 2nd ICS MCL
New guidance - 4-5th ICS MAL
Needle should be inserted directly above the rib to avoid the NVB
Definitive treatment would include insertion of a chest drain
Anatomical landmarks of the safe triangle of chest drain insertion
Apex - base of the axilla
Anterior - lateral border of pec major
Posteriorly - lateral border of lattismus dorsi
Inferiorly - 5 ICS
Drain inserted directly above rib below to avoid NVB
What structures are passed during chest drain insertion?
- skin
- superficial fascia
- subcutaneous fat
- external intercostal muscle
- internal intercostal muscle
- innermost intercostal muscle
- parieral pleura
Nerve supply of the diaphragm
Left and righ phrenic nerves C3,4,5
What structures pass through the diaphragm at T8?
IVC
Right phrenic nerve
What structures pass through the diaphragm at T10?
Oesophagus
Vagus nerves
What structures pass through the diaphragm at T12?
Aorta
Azygos vein
Thoracic duct
Why does gallbladder pain sometimes refer to the right shoulder?
Sensory supply of the diaphragm is via the phrenic nerve (C3,4,5)
Pain may be referred to the C3,4,5 dermatome across shoulder