Thoracic Wall Flashcards
How many ribs are there?
12 pairs
How many are true ribs?
1-7 - reach the sternum
How many are false ribs?
8-10 - reach costal cartilage above 11-12 are floating
Where are the articulations of the ribs?
With vertebral column via head and tubercle (articular facets) With sternum - costal cartilage
How many thoracic vertebrae?
12 - each rib joined to one vertebra
Where is the sternum?
Anterior of the heart
How is the sternum made up?
**** Jugular notch **** 3 parts: Manubrium, Body and Xiphoid process (xiphisternum) **** Sternal angle **** (important landmark)
Which ribs attach to the Manubrium?
1st costal cartilages
Which ribs attach to the sternal angle?
2nd costal cartilage
Which ribs attach to the body of the sternum?
3-7th
Where do the 8-10th ribs attach?
To the cartilage above
What is the costal margin?
Outline of cartilage where the diaphragm is attached - the bottom most bit of ribcage
Why is the sternal angle important?
Landmark for 2nd ribs
What are the contents of the thoracic inlet?
Great vessels heading for neck and upper limbs - common carotid, internal jugular and subclavian Oesophagus, trachea, nerves, lymphatics
What is the thoracic inlet formed from?
1st ribs, T1, Manubrium
Where is the major capacity for thorax expansion?
Lower parts of thorax
What is the diaphragm?
Formed from flat central tendon, with muscle radiating to costal margin and vertebrae
How does the diaphragm function?
Dome flattens, ^ vertical diameter of chest Pulls costal margin up to ^ transverse and anteroposterior diameter
What is the secondary role of the intercostals?
Stiffen the chest wall, improve efficiency of breathing movements
How many layers of intercostal muscles are there?
3: external, internal, innermost
What way are the EIM positioned?
Towards your pockets (/// on RHS) - from lower border of rib above, to rib below
Where and by what are EIM replaced?
By anterior intercostal membrane at costo-chondral junction (rib-cartilage)
What way are IIM positioned?
Towards back pockets (/// on LHS) - attachments anteriorly at sternum from lowerb order of rib above to rib below - replaced by membrane posteriorly
What way are IM arranged?
Like plywood - with EIM and IIM forming right angles against each other
How many intercostal nerves?
11 pairs - T1-11 (1 subcostal - T12) - have both motor and sensory functions
Where do the intercostal nerves supply?
Intercostal spaces - lateral cutaneous branch(ant (both medial and lateral) and post)
How is the vasculature arranged in the intercostals?
Arranged in neurovascular bundles - running just below rib deep into internal intercostal
What are the implications of the neurovascular bundles IM, when a chest drain is needed?
A space where no nerves are present is needed - Safe area/triangle!
Where is the safe triangle?
5th intercostal space ant to mid axillary line Ant. border of latissimus dorsi, lateral border of pectoralis major, line superior to nipple and apex below axilla
Where does each IC artery anastamose?
At the end of the intercostal space - so either posterior (in front of vertebrae) or anterior (behind sternum)
What does anastamose mean?
Joining of vessels that supply the same area e.g.: IC artery joins with a major artery (aorta) at end of IC space
Where do the IC nerves come from?
ONLY from spinal cord
What vessels supply blood to the thorax?
Subclavian artery supplies O2 by separating into internal thoracic artery (ITA) ITA separates into Anterior intercostal artery and musculophrenic artery
What does the thoracic cavity contain?
Lungs - in each pleural cavity Mediastinum (between pleural cavities): Heart (pericardial sac), Great vessels, Oesophagus, Trachea, Thoracic duct and major lymph trunks, lymph nodes, Phrenic and vagus nerves
Where does pec. major lie?
Begins at the top of humerus (intertubercular sulcus of humerus) Medial half of clavicle and anterior surface of sternum, first 7 cartilages
What is the function of pec. major?
Adduction, medial rotation and flexion of humerus at shoulder joint
What does adduction mean?
movement towards the mid-line of the body - also applies to movements inwards and across the body
What are the structures with which the rib articulates?
Articular facets or tubercle - and on vertebrae called facets for articulation with head/tubercle
Where is the scapula and what is it?
The shoulder blades - on shoulder towards back
