Thorax Anatomy Flashcards
What are the borders of the breast?
Lateral border of sternum
Mid-axillary line
2nd rib
6th rib
What underlies the breast?
Subcutaneous tissue, contained within retromammary space (bursa)
How is the breast separated from the deep muscles of the chest?
Retromammary space
Layers of fascia
- Pectoral fascia
- Fascia covering serratus anterior
Where do tumours of the breast drain?
Axillary nodes
Thoracic nodes
How do the ribs articulate anteriorly?
Via costal cartilage
Describe the costal cartilage articulations
Costal cartilages 1-7 articulate directly with manubriosternal complex
Costal cartilages 8-10 articulate with costal cartilage above
Costal cartilage 11 and 12 don’t articulate with anything
What are the features of a thoracic vertebra?
Demi-facets on body
Facets on transverse process
Long, vertebrally-oriented spinous process
What do the costovertebral joints join?
Between head of rib and facets on vertebral body
What is the ligament associated with the costovertebral joint?
Radiate ligament
- Very strong
- Ribs usually break before dislocation of radiate ligament
What do the costotransverse joints join?
Between tubercle of rib and transverse process of same number as rib
What are the ligaments associated with the costotransverse joint?
Costotransverse ligament - from neck of rib to transverse process
Lateral costotransverse ligament - from tubercle of rib to tip of transverse process
Superior costotransverse ligament - broad band joining crest of neck of rib to transverse process superior to it
What is the significance of a flail chest segment?
Flail chest segment sucked in during inspiration
Arises due to vertical lines of fracture on 2 sides > creates flail segment
What structure fills the internal thoracic aperture/thoracic inlet?
Suprapleural membrane
Continuation of endothoracic fascia
What does the suprapleural membrane do?
Houses thoracic cavity
Prevents lungs from being inspired into neck
What is the relationship between the endothoracic fascia and the parietal pleura?
Endothoracic fascia external to parietal pleura
What are the attachments of the diaphragm to the abdominal wall?
Right crus attaches to anterior aspect of L1-3
Left crus attaches to anterior aspect of L1-2
Which of the crura are longer?
Right, because it’s higher due to position of liver
What are the three orifices that pass through the diaphragm?
Aortic hiatus
Oesophageal hiatus
Caval opening
Where is the aortic hiatus?
Midline T12
Between crura, behind muscular diaphragm
Where is the oesophageal hiatus?
T10
In right crus, through muscular diaphragm
Where is the caval opening?
T8
Perforates central tendon to right of midline
What are the three types of intercostal muscles, from external to internal?
External intercostal
Internal intercostal
Innermost intercostal
What is the direction of the external intercostal muscles?
Front pocket muscle
Fibres project anteroinferiorly
What is the function of the external intercostal muscles?
Contracts > pulls ribs out - expands rib cage during inspiration
Where are the external intercostal muscles?
Occupy intercostal spaces from tubercles of ribs posteriorly to costochondral junctions anteriorly
Each muscle attaches
- Superiorly to inferior border of rib above
- Inferiorly to superior border of rib below
Which muscles are the external intercostal muscles continuous with?
External oblique muscles
What are the fibres of the external intercostal muscles replaced by anteriorly?
External intercostal membranes
What is the direction of the internal intercostal muscles?
Back pocket muscle
Fibres extend posteroinferiorly
What is the function of the internal intercostal muscles?
Contract and splint spaces between to stop it being sucked in
Where are the internal intercostal muscles?
From floor of costal grooves to superior border of ribs inferior to them
What is the internal intercostal muscle replaced by anteriorly?
Internal intercostal membrane
What is the distribution of the innermost intercostal muscles?
Discontinuous
What is the direction of the fibres of the innermost intercostal muscles?
Back pocket direction
What is the function of the innermost intercostal muscles?
Essentially same as internal intercostals, but separated from them by intercostal nerves and vessels
What is the layout of the neurovascular bundle in the intercostal space?
Superior to inferior
- Vein
- Artery
- Nerve
Where is the neurovascular space located?
In costal groove
What structure receives the posterior intercostal veins?
Azygous vein
In what dimensions can the thorax change due to elevation of the ribs, and how?
Vertical via diaphragm
Lateral vial elevation of ribs - move like bucket handle
A-P direction via elevation of upper ribs > moves sternum upwards and forwards - like pump handle
What are the accessory muscles of respiration?
Muscles in neck; eg
- Scalenes
- Sternocleidomastoid
Muscles in abdomen
Why are the accessory muscles of respiration able to influence it?
Can move rib cage > can change thoracic volume > can influence respiration
What is the transverse pericardial sinus?
Transversely running passage within pericardial cavity between coronary inflow and outflow tracts (covered in serous pericardium)
What is the clinical significance of the transverse pericardial sinus?
Can be used during cardiac surgery for passage of surgical clamp/ligature to tie off aorta and pulmonary trunk to divert circulation
Where is the fossa ovalis?
In interatrial septum = posterior wall of right atrium and anterior wall of left atrium
What are the ridges in the wall of the right ventricle called?
Trabeculae carnae
Where are the trabeculae carnae in the walls of the right ventricle?
Everywhere except for immediately below pulmonary valve at conus arteriosus/infundibulum
What are the functions of the heart’s fibrous skeleton?
Anchors atrial and ventricular muscle masses and electrically isolates them
Provides attachment for base of each valve cusp
What are the components of the fibrous skeleton of the heart?
2 conjoined rings in figure 8s surrounding atrioventricular valves
2 coronets surrounding semilunar valves
Which surface of the atrioventricular valves is smooth and rough?
Atrial surface = smooth
Ventricular surface = rough
Why is the ventricular surface of the atrioventricular valves rough?
For attachment of chordae tendineae
How does the atrioventricular valve close?
Atrium stops contracting > valve shuts because of pressure difference
Ventricle contracts > papillary muscle contracts to maintain closure of valves
Why are there no papillary muscles and chordae tendineae for semilunar valves?
Pressure generated by ventricular contraction sufficient to push valves open
Where are the aortic sinuses located?
Bulb/blow out of wall of aorta near valve cusps
Where is the bundle of His located?
Between atria and ventricles
What does the bundle of His do?
Carries electrical impulses across fibrous skeleton from atria to ventricles
Where is the cardiac plexus located?
At base of heart
What are the divisions of the cardiac plexus?
Superficial
Deep
What branches does the cardiac plexus receive?
From
- Vagus
- Sympathetic trunks
What is the origin of the right coronary artery?
Right aortic sinus
What is the course of the right coronary artery?
Follows coronary (AV) sulcus between atria and ventricles
What is the distribution of the right coronary artery?
Right atrium
Sinoatrial and atrioventricular nodes
Posterior part of interventricular septum
What does the right coronary artery anastomose with?
Circumplex and anterior branches of interventricular branches of left coronary artery
What is the origin of the sinoatrial nodal artery?
Right coronary artery near its origin (60%)
Circumflex branch of left coronary artery (40%)
What is the course of the sinoatrial nodal artery?
Ascends to sinoatrial node (60%)
Ascends on posterior surface of left atrium to sinoatrial node (40%)
What is the distribution of the sinoatrial nodal artery?
60% - Pulmonary trunk - Sinoatrial node 40% - Left atrium - Sinoatrial node
What is the origin of the right marginal artery?
Right coronary artery
What is the course of the right marginal artery?
Passes to inferior margin of heart and apex
What is the distribution of the right marginal artery?
Right ventricle
Apex of heart
What does the right marginal artery anastomose with?
Interventricular branches
What is the origin of the posterior interventricular artery?
Right coronary artery (67%)
Left coronary artery (33%)
What is the course of the posterior interventricular artery?
Runs in posterior interventricular groove to apex of heart
What is the distribution of the posterior interventricular artery?
Right and left ventricles and posterior third of interventricular septum
What does the posterior interventricular artery anastomose with?
Anterior interventricular branch of left ventricular artery at apex
What is the origin of the atrioventricular nodal artery?
Right coronary artery near origin of posterior interventricular artery
What is the course of the atrioventricular nodal artery?
Passes to atrioventricular nodal artery
Wat is the distribution of the atrioventricular nodal artery?
Atrioventricular node
What is the origin of the left coronary artery?
Left aortic sinus
What is course of the left coronary artery?
Runs in atrioventricular groove and gives off anterior interventricular and circumflex branches
What is the distribution of the left coronary artery?
Most of left atrium and ventricle
Interventricular septum
Atrioventricular bundles
May supply atrioventricular node
What does the left coronary artery anastomose with?
Right coronary artery
What is origin of the anterior interventricular artery?
Left coronary artery
What is the course of the anterior interventricular artery?
Passes along anterior interventricular groove to apex of heart
What is the distribution of the anterior interventricular artery?
Right and left ventricles
Anterior 2/3 of interventricular septum
Whad does the anterior interventricular artery anastomose with?
Posterior interventricular branch of right coronary artery at apex
What is the origin of the circumflex artery?
Left coronary artery
What is the course of the circumflex artery?
Passes to left of atrioventricular sulcus and runs to posterior surface of heart
What is the distribution of the circumflex artery?
Left atrium
Left ventricule
What does the circumflex artery anastomose with?
Right coronary artery
What is the origin of the left marginal artery?
Circumflex branch of left coronary artery
What is the course of left marginal artery?
Follows left border of heart
What is the distribution of the left marginal artery?
Left ventricle
What does the left marginal artery anastomose with?
Interventricular branches
Where do the subclavian and internal jugular veins unite to form the brachiocephalic veins?
Behind medial ends of clavicles
Where do the two brachiocephalic veins meet to for the superior vena cava?
Behind 1st right costal cartilage
Where does the superior vena cava enter the right atrium?
Behind 3rd right costal cartilage
Where does the superior vena cava receive the azygous vein?
Behind 2nd right costal cartilage
Azygous vein arches and enters into back of superior vena cava
What vein is used for central venous catheterisation?
Internal jugular vein
What is contained with the concavity of the aortic arch?
Left lung root structures entering/exiting hilum of left lung
Where is the ligamentum arteriosum located?
At point of bifurcation of pulmonary trunk
What are the four features used to identify the phrenic nerves?
Descend down scalenus anterior from cervical plexus
Passes between subclavian artery and vein
Anterior to lung root
Passes through diaphragm
What are the functions of the phrenic nerves?
Sensory supply to mediastinal and diaphragmatic pleura and pericardium
Motor supply to diaphragm
What are the five features used to identify the right vagus nerve?
Runs in carotid sheath related to carotid artery
Runs alongside trachea and gives off right laryngeal branch > loops around right subclavian artery
Descends behind lung root structures
Runs onto anterior surface of oesophagus
Slips through with oesophagus at level of T10
What are the five features used to identify the left vagus nerve?
Runs in carotid sheath related to carotid artery
Runs lateral to aortic arch
Descends posterior to lung root structures
Runs onto anterior oesophageal surface
Meets right vagus at oesophageal plexus and descends through diaphragm in oesophageal hiatus
What structure is the recurrent laryngeal nerve associated with after it is given off by the left vagus nerve?
Hooks around ligamentum arteriosum
Runs up towards laryngeal structures in left tracheoesophageal groove
Where does the oesophagus enter the diaphragm?
At muscular part of midline to left of it at level of T10
Descends forwards and to left
Describe the path of the descending thoracic aorta?
Goes from left vertebral column
Descends posteriorly and moves centrally
Passes behind oesophagus
Passes through diaphragm in midline between crura at level of T12 = aortic hiatus
What structures are contained within the posterior mediastinum?
Descending thoracic aorta
Oesophagus with vagal plexus at front and thoracic duct at back
Azygous vein
Sympathetic trunk
What are the branches of the descending thoracic aorta?
Posterior intercostal arteries - In pairs > 1 on each side Bronchial arteries which enter hilum of lung Oesophageal arteries Pericardial arteries
Where does the thoracic duct empty into the blood supply?
Into junction of left internal jugular and left subclavian veins
What are the divisions of the parietal pleura?
Cervical Mediastinal Costal Diaphragmatic Costodiaphragmatic recess
Where does the visceral pleura reflect back on itself and become the parietal pleura?
Reflects off hilar structures
Reflects onto lateral surface of mediastinum to become mediastinal parietal pleura
What is the pulmonary ligament?
Double fold of pleura hanging down from hilar structures - pleural sleeve larger than hilar structures it surrounds
Dead space > allows for expansion of pulmonary veins
Where does the trachea start and end?
Start = neck at C6
Divides into right and left main bronchi at T4/5
Describe the cross section of the trachea
Series of U shaped cartilage rings closed posteriorly by trachealis muscle
Always open
What area of the lung do segmental bronchi supply?
Each segmental bronchus supplies bronchopulmonary segment
Describe the bronchopulmonary segments
Pyramid shaped with apex directed to hilum and base on surface
Supplied by segmental bronchus, artery, and vein
Represents zones of functionally distinct lung tissue
Why is the apical segment of the lower lobe significant?
1st segment to come off directly posteriorly
Site where vomitus/aspirates will travel if patient supine
- Auscultated if fluid/aspirate suspected
What are the lung fissures lined by?
Continuous layer of visceral pleura
How is the left lung identified?
Cardiac notch
Lingula below cardiac notch
Should only have 2 lobes - not definitive
Where are the pulmonary arterial structures located in relation to the bronchial tree?
Anterior
What is contained in each lung hilum?
Pulmonary artery > anterior to bronchial tree
Pair of pulmonary veins > anteriorr pulmonary vein anterior to pulmonary artery
Bronchi > bronchus intermedius in right hilum
Lymphatics
Bronchial arteries/veins
Nerves
What are the imprints seen on the medial view of the right lung?
Superior vena cava
Arch of azygous vein
Right atrium
What are the imprints seen on the medial view of the left lung?
Left ventricle Aorta - Ascending - Arch - Descending thoracic Much deeper imprints than those on right lung
How are the surface lymphatics of the lung visible?
As black “spider webs” just deep to visceral pleura, due to inhaled carbon particles
Describe the lymphatic drainage of the lungs
Superficial plexus lies deep to visceral pleura and drains
- Lung parenchyma
- Visceral pleura
Deep plexus lies in submucosa of bronchi and in peribronchial connective tissue and drains lung root structures
Describe the nerve supply to the lungs
Autonomic nerve supply of both sympathetic and parasympathetic nervous system regulates
- Mucus production
- Diameter of bronchioles
Pulmonary plexus associated with bifurcation of trachea > hilar plexus > nerves track into lung
What is contraast resolution?
Ability to differentiate soft tissues
