2. The Thoracic Wall

Question 1

Anterior (ventral)

Answer 1

Towards FRONT of body

Question 2

Posterior (dorsal)

Answer 2

Towards BACK of body

Question 3

Superior (cranial)

Answer 3

Towards HEAD

Question 4

Inferior (caudal)

Answer 4

Towards FEET

Question 5

Midline (median), mid-sagittal

Answer 5

Straight down middle, divides body into 2 equal sides

Question 6

Medial

Answer 6

Towards the midline

Question 7

Lateral

Answer 7

Away from the midline

Question 8

Proximal

Answer 8

Towards body (when referring to a limb)

Question 9

Distal

Answer 9

Away from body (when referring to a limb)

Question 10

Superficial

Answer 10

Close to surface

Question 11

Deep

Answer 11

Far from surface

Question 12

Sagittal

Answer 12

Cuts through from front to back (vertical)

Question 13

Frontal (coronal)

Answer 13

Cuts through from side to side

Question 14

Horizontal (transverse or axial)

Answer 14

Cuts through horizontally to body

Question 15

Number of thoracic vertebrae

Answer 15

12

Question 16

Number of pairs of ribs

Answer 16

12

Question 17

Describe the arrangement of the ribs.

Answer 17

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: Lack anterior attachment (not connected to sternum)

Question 18

What are articulations? Describe the articulations of the ribs

Answer 18

Joinings
All ribs articulate with vertebral column via head and tubercle
Most of the ribs articulate with costal cartilages

Question 19

Tubercle

Answer 19

Sticks out of a bony structure, provides site of attachment for ligaments/ muscles

Question 20

Facet

Answer 20

Place where bones join to other bones

Question 21

Where is the ribcage wider?

Answer 21

Bottom

Question 22

How do the ribs slope as they come to the anterior?

Answer 22

Ribs slope downwards as they come to the anterior

Question 23

What are the 3 divisions of the sternum?

Answer 23

Manubrium
Body
Xiphoid

Question 24

Where does the 1st rib attach medially?

Answer 24

Manubrium

just inferior to the sternoclavicular joint

Question 25

Where does the 2nd rib attach medially?

Answer 25

Manubriosternal joint (STERNAL ANGLE)

Question 26

Where do ribs 3 to 7 attach medially?

Answer 26

Sternum

Question 27

Where do ribs 8 to 10 attach medially?

Answer 27

Costal cartilage above

Question 28

What defines the thoracic inlet (superior thoracic aperture)?

Answer 28

1st pair of ribs 1st thoracic vertebra (T1) Manubrium

Question 29

Contents of thoracic inlet

Answer 29

Great vessels from heart emerging to supply head, neck and upper limb Oesophagus, trachea, nerves and lymphatics descending = Vulnerable area as not protected by a ‘bony cage’

Question 30

Describe the structure of the diaphragm.

Answer 30

Has a flat central tendon with muscle radiating to costal margin and vertebrae.

Question 31

What is the role of the intercostal muscles?

Answer 31

Stiffen the chest wall to improve the efficiency of breathing movements.

Question 32

How does the diaphragm move in inspiration?

Answer 32

Dome flattens to increase vertical diameter of chest | Pulls costal margin up to increase transverse and antero-posterior diameters

Question 33

How do the ribs move in inhalation?

Answer 33

Sternum moves out and up Ribs swing out and up, “become more horizontal” Dimensions of thoracic cavity increase antero-posteriorly and medio-laterally

Question 34

How are the intercostal muscles arranged? State the directions of the muscle fibres.

Answer 34

External intercostal: Inferomedially (like hands in pockets) from lower border of rib above to rib below At the costo-chondrial junction it is replaced by an anterior intercostal membrane Internal Intercostal: Supromedially Attachments begin anteriorly at the sternum Perpendicular to external intercostals Replaced by a membrane posteriorly Innermost intercostal: Same orientation as internal

Question 35

Where is the neuromuscular bundle? Describe the structure

Answer 35

``` Just below rib Between internal and innermost intercostals Vein most superior Artery in middle Nerve below ```

Question 36

How many intercostal nerves are there?

Answer 36

11 pairs (T1 - T11) and a subcostal nerve (T12) A mix of motor and sensory nerves Supply the intercostal spaces

Question 37

Describe the branching of intercostal nerves.

Answer 37

Lateral cutaneous branch (which splits into an anterior and a posterior branch) Anterior cutaneous branch (which splits into a medial and a lateral branch)

Question 38

Is the neuromuscular bundle protected?

Answer 38

Bottom of rib is like a collar, protects blood vessels but nerve hangs just below

Question 39

What implications does the location of the neuromuscular bundle have for putting a needle or chest drain through the thoracic wall?

Answer 39

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

Question 40

What are the borders for the safe area for inserting a chest drain?

Answer 40

Anterior border of the latissimus dorsi Lateral border of pectoralis major A line superior to the horizontal level of the nipple Apex below the axilla In general: 5th intercostal space, anterior to the mid-axillary line

Question 41

What is the difference in anastomoses between the nerves and blood vessels in the neuromuscular bundle?

Answer 41

Nerves only emerge from spinal cord and have to make way to anterior Blood vessels come from tributaries of major vessels anterior and posterior

Question 42

Anastomosis

Answer 42

Region where arteries/ veins from different directions (front and back) are in close proximity supply same area of tissue

Question 43

What do the internal thoracic arteries branch from?

Answer 43

Right and left subclavian arteries

Question 44

What major artery do the intercostal arteries anastomose with?

Answer 44

Internal thoracic

Question 45

What is the space between the pleural cavities of each lung called?

Answer 45

Mediastinum

Question 46

To what height do the lungs extend to?

Answer 46

2-3cm above the clavicle