Thoracic Walls Flashcards
What is the area of the base of the breast?
2nd to 6th rib, border of sternum to mid axillary line with a suprolateral extension towards the axilla (axillary tail)
In which quadrant of the breast is there a higher incidence of tumor?
The upper outer quadrant - because it has a larger area due to the axillary tail
What is the submammary space?
The space between the breast tissue and the underlying muscle
What is the arterial supply of the breast?
Arteries come in laterally via the lateral thoracic artery and the lateral cutaneous branches of posterior intercostal arteries and also medially from the internal thoracic artery
What is the venous drainage of the breast?
Follows the pattern of the arteries - medial and lateral
What is the lymphatic drainage of the breast?
Drains laterally to the axilla (which can be palpated) and medially to the internal thoracic nodes (which can’t be palpated)
How many ribs are there?
12 pairs
What are the true ribs?
Ribs 1-7 which articulate directly with manubriosternal cartilage
What are false ribs?
Ribs 8-10 which articulate with the costocartilage above
What are floating ribs?
Ribs 11-12 which don’t articulate anteriorly
What is the structure of a typical rib?
Head of the rib has two articular facets, tubercle with two facets (medial is articular and lateral is rough), shaft, groove on inferior margin of internal aspect, pit at the sternal end for costal cartilage
Which ribs are atypical?
1,2,11,12
What are the 3 significant features of thoracic vertebrae?
demi-facets on the vertebral body, facets on the tips of the transverse processes, long vertical spinous processes
What is the costovertebral joint?
The joint between the head of the rib and the demi facets on the vertebral bodies
What is the costotransverse joint?
The joint between the tubercle of the rib and the transverse processes of the thoracic vertebrae
How is the superior aperture of the thoracic cage reduced in dimension?
By the supra plural membrane - to stop the lungs expanding into the neck
What is the origin of the diaphragm?
xiphoid process, costal margin, tips of the 11th and 12th rib, arcuate ligaments (fascia overlying muscles of the posterior wall), left and right crus
Which crus is longer?
The right crus (L1-3) - compared with only L1,2 for the left crus
What is the insertion of the diaphragm?
The central tendon
What are the 3 major apertures in the diaphragm?
caval orifice, oesophageal hiatus and the aorta
Where is the caval orifice?
At T8 to the right of the midline
Where is the oesophageal hiatus?
At T10 slightly to the left of the midline
Where is the aortic hiatus?
At T12 between the crura against the lumbar vertebral column
What is the nerve supply of the diaphragm?
The right and left phrenic nerve
What are the 3 muscles of the intercostal space?
External, internal and innermost
In what direction are the fibres of the external intercostal muscle?
anteroinferior - hands in front pockets
What is the action of the external intercostal muscles?
Pulls ribs below up and out to expand the rib cage in inspiration
What area of the intercostal space does the external intercostal muscle cover?
The whole space posteriorly, laterally and anteriorly up until it is replaced by the external intercostal membrane
In what direction are the fibres of the internal intercostal muscles?
posteroinferior - hands in back pockets
What is the action of the internal intercostal muscles?
Pulls ribs down and in
What area of the intercostal space does the internal intercostal muscle cover?
The whole space anterior, laterally and posteriorly up until it is replaced by the internal intercostal membrane
In what direction are the fibres of the innermost intercostal muscles?
Posteroinferior - hands in back pockets
What is the action of the innermost intercostal muscles?
Pulls ribs down and in
What area of the intercostal space does the innermost intercostal muscle cover?
Discontinuous - covers some parts but not all - mostly lateral
Where is the neuromuscular bundle found in there intercostal space?
In the intercostal groove at the top of the intercostal space between the internal and innermost intercostal muscles
In what order are the vessels in the neuromuscular bundle?
Vein, artery, nerve from above down
What nerve runs through the intercostal space?
The intercostal nerve - the ventral rams of the spinal nerve - it gives off cutaneous branches laterally and anteriorly
What arteries run through the intercostal space?
The posterior intercostal artery (a branch of the thoracic aorta) and the anterior intercostal artery (a branch of the internal thoracic artery)
What veins run through the intercostal space?
The anterior intercostal vein (drains into the internal thoracic vein) and posterior intercostal vein (drains into the azygous vein)
How does the thoracic cage increase in an antero-posterior direction?
By elevating the upper ribs which pushes the sternum forward
How does the thoracic cage increase in the lateral dimension?
By elevating the lower ribs
What are some of the accessory muscles of respiration?
sternocleidomastoid, scalenes, abdominals muscles
