Week 1: Thoracic Anatomy Flashcards
Which are the true ribs?
1-7
Which are the false ribs?
8-10
Which are the floating ribs?
11-12
Which tissue do the thoracic cage and wall refer to respectively?
cage: skeletal wall: muscular
Which structures pass through the inferior thoracic aperture? Also think of the level of passage through the diaphragm
- oesophagus (T10 - level of passage through diaphragm) - aorta (T12 - level of passage through diaphragm) - inferior vena cava (T8 - level of passage through diaphragm) - thoracic duct - azygous vein - phrenic nerve
At what level are the oesophageal and aortic hiatus respectively?
T10 and T12
Name 4 functions of the thoracic cage
- protect throacic organs - protect abdominal organs - provide attachment for muscles - support the weight of the upper limbs
Name the components of the thoracic cage
- thoracic vertebrae - intervertebral discs - ribs - sternum - costal cartilages
What cartilage type makes up the costal cartilage?
hyaline
How many ribs are there in total?
12
In which ways does the thoracic cage expand (3)?
- Ribs elevate and flare out (transverse plane increase) - Sternum and distal ribs elevate and move anteriorly (sagittal plane) - Diaphragm contracts and moves inferiorly (coronal plane)
How does Boyle’s Law explain inspiration through an increase in the thoracic space
The increase in volume is inversely proportional to the air pressure. This means an increase in volume decreases the pressure and creates a negative pressure compared to atmospheric air. This negative pressure causes air to move into the lungs
To which structures does the diaphragm attach
Xiphoid process - Costal margin - Lateral floating ribs - T12 - Central tendon (insertion)
Which 3 main structures pass through the diaphragm?
- IVC (level T8) - oesophagus (Level T10) - aorta (Level T12)
What is the nervous spply of the diaphragm? (nerve+roots)
phrenic nerve via anterior rami of C3,4,5
Describe the external intercostal muscle (activity, fibre direction)
Fibres run inferio-medially - Active during inspiration
Describe the internal intercostal muscle (activity, fibre direction)
- Fibres run inferiolaterally - Active during expiration
Where do the intercostal muscles originate and insert?
They attach at the inferior border of the superior rib and the superior border of the inferior rib
Name the accessory muscles to inspiration
- Scalenes - Sternocleidomastoid - pectoralis major - pectoralis minor - serratus anterior - serratus posterior - levator costarum
What is the neurovascular supply of the intercostal space?
One large, major neurovascular bundle underlying the rib and one collateral neurovascular bundle just superior to the lower rib
Where do neurovascular bundles run in the intercostal space?
Under each rib in the costal groove between the internal and the innermost intercostal muscle
In which order do the vessels and nerve in the neruovascular bundle travel from superior to inferior?
Vein -> artery -> nerve
What is the advantage of having the vein, artery, and nerve ordered in the way that they are?
The vein is most susceptible to bleeding out of the vessels so it is most protected superiorly. The artery is better designed to constrict to reduce blood loss. The nerve is least protected, as branches from separate nerves overlap and supply the skin overlying the rib even if one nerve is damaged.
Which larger arteries supply the intercostal arteries posteriorly?
Posteriorly-Superiorly (Rib 1+2): the subclavian via the costocervical branch and supreme intercostal artery. Posteriorly-Inferiorly: the aorta
Which larger arteries supply the intercostal arteries anteriorly?
Anteriorly: the internal thoracic artery from the subclavian until the 6th rib where internal thoracic divides into the superior epigastric and the musculophrenic arteries. From this level the intercostal space is supplied by the musculophrenic artery
What the gender-based difference in vasculature in the intercostal blood supply?
the 2nd to 5th anterior intercostal arteries are larger in females to supply the breasts. All other intercostal arteries are smaller in females than in males
Where do the intercostal veins drain posteriorly?
The azygous system of veins: on the right into the azygous vein. On the left into brachiocephalic vein (Rib 1-3) the hemiazygous vein (Rib 4-8) and accessory hemiazygous vein (Rib 9-12) The hemiazygous and its accessory both drain into the azygous which then drains into the SVC
Where do the intercostal veins drain anteriorly?
The internal thoracic veins which drain into the brachiocephalic veins
Describe the course and branches of the intercostal nerve
The intercostal nerve arises from the anterior ramus. It travels in the costal groove. The nerve branches superficially to give rise to the lateral cutaneous nerve and anteriorly to give rise to the anterior cutaneous nerve.
Comment on intercostal nerve overlap
The intercostal nerves overlap with branches from the same side superiorly and inferiorly, but there is little overlap between the right and left side of the body past the midline
Describe the lymphatic drainage of the thorax and its venous destination
The lymphatic drainage is via the parasternal nodes, the intercostal nodes and diaphragmatic nodes. These drain into the thoracic duct which drains into the left brachiocephalic vein
Where would you enter a chest drain?
At the intersection of a line from the 5th intercostal space (nipple-line) and the mid-axillary line, above a rib (as to sacrific collateral branches rather than intercostal neurovasculature
Which nerves supply the thoracic wall?
2nd-6th intercostal nerves
Which nerves supply the abdominal skin and muscles?
7th-11th intercostal nerves
What superficial area is supplied by the subcostal nerve?
The anterior inferior abdominal wall
Fill the blanks and add which other structures pass through the superior thoracic aperture (10 in total)
- oesophagus
- right common carotid
- trachea
- internal jugular vein (passes through via brachiocephalic)
- apex of lung
6+7. (right) subclavian artery and vein - brachiocephalic artery
- brachiocephalic veins
- vagus nerve
- phrenic nerve
Fill the blanks
- IVC
- oesophagus
- aorta
- central tendon of diaphragm
- aortic hiatus
- oesophageal hiatus
fill the blanks
- Manubrium
- Body of sternum
- Xiphoid process
- sternal angle (aka manubriosternal joint)
- jugular notch
- transverse ridges
- articular surface for clavicle
- articular surface for rib 1
- articular demifacets for rib 2
- articular facets for ribs 3-6
- articular facet for rib 7
Fill the blanks
- Head
- Neck
- Shaft
- Tubercle
- Costal groove
Fill the blanks
- External intercostal muscle
- Internal intercostal muscle
- Innermost intercostal muscle
- External intercostal membrane
