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