2 - The Thoracic Wall Flashcards
What are the costal cartilages?
Small bars of hyaline cartilage between the ribs and the sternum (that serve to prolong the ribs forward and contribute to the elasticity of the walls of the thorax)
What is meant by superior (cranial/rostral) and inferior (caudal)?
superior - towards the head
inferior - towards the feet
What do the terms ‘true’, ‘false’ and ‘floating’ mean and which ribs do they refer to?
TRUE - ribs attach directly to the adjacent costal cartilage
1-7
FALSE - ribs attach to the costal cartilage above/superiorly
8-10
FLOATING - lack anterior attachment
11-12
What is meant by an articulation?
a joint
What is a tubercle and what is its function?
A tubercle is a raised/sticking out portion of bone
Its function is to act as an attachment to muscles and ligaments
What is the costal margin?
The lower edge of the chest (thorax) formed by the bottom edge of the rib cage. It is the medial margin formed by the 7th to 10th ribs.
What are the contents of the thoracic inlet?
the great vessels heading for the neck and upper limbs, oesophagus, trachea, nerves and lymphatics
What are the 3 parts of the sternum (breastbone)?
the manubrium
the body
the xiphoid
Does the costal groove lie at the superior or inferior end of each individual rib?
inferior
Where des the 2nd CC join to the sternum?
at the manubriosternal joint/the sternal angle
Which CCs join to the sternum?
3-7
Where is the most lung tissue and the most capacity for lung expansion take place in the thorax?
in the lower parts (the bottom of the thorax is larger than the top)
What is the diaphragm (structurally)?
It has a flat central tendon with muscle radiating to costal margin and vertebrae
How do the muscles (diaphragm) change to increase the chest and lung volume?
1st – dome flattens to increase vertical diameter of chest. 2nd – pulls costal margin up to increase transverse and antero-posterior diameters
What is the secondary role of the intercostal muscles?
stiffen chest wall to improve efficiency of breathing movements
What are the 3 layers of the intercostal muscles? How are they arranged?
EXTERNAL INTERCOSTALS
downwards and laterally from lower border of rib above to rib below.
Replaced by anterior intercostal membrane at costo-chondral (rib-cartilage) junction
(like putting hands into pockets’ - inferiorly and medially
INTERNAL INTERCOSTALS
attachments begin anteriorly at the sternum- from lower border of rib above to rib below - fibres directed at right angles to external intercostals.
superiorly and medial
INNERMOST INTERCOSTALS (relatively trivial)
same orientation and the internal ICs
Where can the intercostal nerves branch from?
There is a lateral cutaneous branch (anterior and posterior) and anterior cutaneous branch (medial and lateral)
What is the order of vessels and nerves in the intercostal neurovascular bundles?
What are the implications for putting a needle or chest drain through the chest wall?
vein—–>artery—–>nerve
The needle should be inserted just superiorly to the rib
What is the ‘safe area’ for inserting a chest drain?
5th intercostal space anterior to mid axillary line
Anterior border of the latissimus dorsi, the lateral border of the pectoralis major muscle, a line superior to the horizontal level of the nipple, and an apex below the axilla.
Describe the superior and inferior edge of the rib
superior surface is round
inferior surface is a sharp edge
Where do the intercostal arteries receive blood from?
Each intercostal artery joins (anastomoses) with a major artery at each end of the intercostal space
Where do the intercostal nerves come from?
only come from the posterior side (from the spinal chord)
What is the mediastinum?
the space between the 2 pleural cavities
What lies in the mediastinum?
Heart (lying in its pericardial sac) Great vessels Oesophagus Trachea Thymus Thoracic duct and other major lymph trunks Lymph nodes Phrenic and vagus nerves
Where do the internal thoracic arteries stem from?
they are branches of the subclavian arteries
