Thoracic wall Flashcards
Describe the arrangement of the ribs.
Ribs 1-7 are true ribs - their costal cartilages articulate directly with the sternum
Ribs 8-10 are false ribs - their costal cartilages join onto the costal cartilages of the ribs above them before joining the sternum
Ribs 11 + 12 are floating ribs - they have costal cartilage but it doesn’t articulate with anything. There is not connection with the sternum.
What do the ribs articulate with?
The costal cartilage anteriorly and the vertebral column via the head and tubercle of the rib
Where does the first rib attach medially?
Manubrium - just inferior to the sternoclavicular joint
What defines the thoracic inlet (superior thoracic aperture)?
1st rib and costal cartilage, 1st thoracic vertebra (T1) and the manubrium
Describe the structure of the diaphragm.
The diaphragm has a central tendon and it is attached to the costal margin and vertebrae.
What is the role of the intercostal muscles?
They stiffen the chest wall to improve the efficiency of breathing movements.
How are the intercostal muscles arranged? State the directions of the muscle fibres.
External intercostal - inferomedially (like hands in pockets) - downwards and laterally from lower border of rib above to rib below. Replaced by anterior intercostal membrane at costo-chondral (rib-cartilage) junction
Internal Intercostal - attachments begin anteriorly at the sternum- from lower border of rib above to rib below - fibres directed at right angles to external intercostals.
Replaced by membrane posteriorly
Innermost intercostal
How many intercostal nerves are there?
11 pairs (T1 - T11) and a subcostal nerve (T12) They involve a mix of motor and sensory nerves and supply the intercostal spaces
Describe the branching of intercostal nerves
There is a lateral cutaneous branch (which splits into an anterior branch and a posterior branch)
There is an anterior cutaneous branch (which splits into a medial branch and a lateral branch)
Innervate the overlaying skin
Where are the intercostal neurovascular bundles found?
Internal intercostal and innermost intercostal
Just below the bottom edge of a rib
What implications does this have for putting a needle or chest drain through the thoracic wall?
As the neurovascular bundle is just below the bottom edge of a rib, you would want to insert the needle just above the superior edge of a rib to avoid piercing the neurovascular bundle
Vein, artery & nerve run just below rib deep to internal intercostal
VAN
Nerve is often not protected by the groove so is most at risk when upper aspect of intercostal space is perforated
What are the borders for the safe area for inserting a chest drain?
Anterior border of the latissimus dorsi
Lateral border of pectoralis major
A line superior to the horizontal level of the nipple. 5th intercostal space
Apex below the axilla
In general - 4th intercostal space, anterior to the mid-axillary line
What major artery do the intercostal arteries anastomose with?
Internal thoracic
What do the internal thoracic arteries branch from?
Right and left subclavian arteries
Which rib articulates with the sternum at the sternal angle?
Rib 2
what to each rib attach to in the sternum?
1st costal cartilages attach to manubrium 2nd to manubriosternal joint 3rd – 7th to sternum 8th – 10th to cartilage above 11th & 12th - floating
Describe the articulations of the ribs?
The vertebral column posteriorly via head and tubercle
Costal cartilages anteriorly with sternum
describe the features of a rib?
Costal groove marks the inferior margin of the internal surface of the rib. The inferior edge is sharp as it is tapered to allow passage of some structures
Angle is at the superior of the rib
Crest separates the two articular surfaces of the head of the rib
Neck separates the head from the tubercle
what is the landmark surface of the sternal angle?
What important things occur at this point?
Sternal angle – Manubrium and body of sternum articulate at T4/T5.
- trachea bifurcation into right and left main bronchi
- apex of aortic arch
- marks the position of the superior limit of the pericardium
- marks where the arch of the aorta begins and ends
- passes through the site where the superior vena cava penetrates the pericardium to enter the heart
- marks the superior limit of the pulmonary trunk
describe the type of joints that the rib form with the sternum?
- Rib 1 and Manubrium: not synovial and consists of a fibrocartilaginous connection between the manubrium and the costal cartilage
- Rib 2 to Rib 7: synovial and have thin capsules reinforced by surrounding sternocostal ligaments
- Rib 8 to Rib 10: bind to costal cartilage above (interchondral joints)
what happens to the joint between the body of the sternum and xiphoid process?
becomes ossified with age.
describe the inter vertebral joints?
1. Symphysis between vertebral bodies = Hyaline cartilage + Intervertebral disc Intervertebral disc is made up of Anulus fibrosus (collagen – limits rotation) Nucleus pulposus (gelatinous – absorbs compression forces)
- Joints between vertebral arches (zygapophysial joints)
Inferior Articular Process + Superior articular process
How does the rib head articulate and the tubercle?
Superior costal facet: articulates with part of the head of its own rib
Inferior costal facet: articulates with part of hte head of the rib below.
Costotransverse joint = synovial joint between
Tubercle of rib and
Transverse process of its own vertebra
what are the exceptions for rib articlations?
- SUPERIOR costal facets on the body of vertebra TI are COMPLETE and articulate with a single facet on the head of its own rib-in other words, the head of rib I does not articulate with vertebra CVII
Rib 1 does not articulate with C7
-vertebra TX (and often TIX) articulates only with its own ribs and therefore LACK INFERIOR demifacets on the body
-vertebrae TXI and TXII articulate only with the heads of their own ribs-they lack TRANSVERSE costal facets and have only a single complete facet on each side of their bodies.
Posterior intercostal arteries are branches of?
Anterior intercostal arteries are branches of ?
Posterior intercostal arteries are branches of the aorta (thoracic aorta)
Anterior intercostal arteries are branches of the internal thoracic artery (running down the chest wall)
what is costo-vertebral joint and costo-transverse ligament?
When the 2 facets of the rib articulate with the vertebral above and below.
When the tubicle articles with the to of the transverse process.
Both are synovial joints
