2 - The Thoracic Wall

Question 1

What are the costal cartilages?

Answer 1

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)

Question 2

What is meant by superior (cranial/rostral) and inferior (caudal)?

Answer 2

superior - towards the head

inferior - towards the feet

Question 3

What do the terms ‘true’, ‘false’ and ‘floating’ mean and which ribs do they refer to?

Answer 3

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

Question 4

What is meant by an articulation?

Answer 4

a joint

Question 5

What is a tubercle and what is its function?

Answer 5

A tubercle is a raised/sticking out portion of bone

Its function is to act as an attachment to muscles and ligaments

Question 6

What is the costal margin?

Answer 6

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.

Question 7

What are the contents of the thoracic inlet?

Answer 7

the great vessels heading for the neck and upper limbs, oesophagus, trachea, nerves and lymphatics

Question 8

What are the 3 parts of the sternum (breastbone)?

Answer 8

the manubrium
the body
the xiphoid

Question 9

Does the costal groove lie at the superior or inferior end of each individual rib?

Answer 9

inferior

Question 10

Where des the 2nd CC join to the sternum?

Answer 10

at the manubriosternal joint/the sternal angle

Question 11

Which CCs join to the sternum?

Answer 11

3-7

Question 12

Where is the most lung tissue and the most capacity for lung expansion take place in the thorax?

Answer 12

in the lower parts (the bottom of the thorax is larger than the top)

Question 13

What is the diaphragm (structurally)?

Answer 13

It has a flat central tendon with muscle radiating to costal margin and vertebrae

Question 14

How do the muscles (diaphragm) change to increase the chest and lung volume?

Answer 14

1st – dome flattens to increase vertical diameter of chest. 2nd – pulls costal margin up to increase transverse and antero-posterior diameters

Question 15

What is the secondary role of the intercostal muscles?

Answer 15

stiffen chest wall to improve efficiency of breathing movements

Question 16

What are the 3 layers of the intercostal muscles? How are they arranged?

Answer 16

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

Question 17

Where can the intercostal nerves branch from?

Answer 17

There is a lateral cutaneous branch (anterior and posterior) and anterior cutaneous branch (medial and lateral)

Question 18

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?

Answer 18

vein—–>artery—–>nerve

The needle should be inserted just superiorly to the rib

Question 19

What is the ‘safe area’ for inserting a chest drain?

Answer 19

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.

Question 20

Describe the superior and inferior edge of the rib

Answer 20

superior surface is round

inferior surface is a sharp edge

Question 21

Where do the intercostal arteries receive blood from?

Answer 21

Each intercostal artery joins (anastomoses) with a major artery at each end of the intercostal space

Question 22

Where do the intercostal nerves come from?

Answer 22

only come from the posterior side (from the spinal chord)

Question 23

What is the mediastinum?

Answer 23

the space between the 2 pleural cavities

Question 24

What lies in the mediastinum?

Answer 24

Heart (lying in its pericardial sac)
Great vessels 
Oesophagus
Trachea 
Thymus
Thoracic duct and other major lymph trunks
Lymph nodes
Phrenic and vagus nerves

Question 25

Where do the internal thoracic arteries stem from?

Answer 25

they are branches of the subclavian arteries