Week 7 - Lungs

Question 1

Which lung is pictured below, right or left? Label the fissures and lobes.

Answer 1

= Right lung as there are 3 lobes (left only has 2)

Question 2

The sternal angle (of Louis) is an important anatomical landmark on the thorax. An imaginary horizontal line from the sternal angle to the inferior endplate of ………. is known as the thoracic plane. List five anatomical structures that are found along this plane.

Answer 2

Sternal Angle = T4

RAT PLANT

• R: rib 2
• A: aortic arch
• T: tracheal bifurcation
• P: pulmonary trunk
• L: ligamentum arteriosum
• A: azygos vein drains into SVC
• N: nerves
  
  • loop of recurrent laryngeal nerve
  • parasympathetic: contributions to the cardiopulmonary plexuses
  • sympathetic: branches of the cardiopulmonary splanchnic nerves
• T: right-to-left movement of the thoracic duct

Question 3

The definitive management of a tension pneumothorax involves insertion of an intercostal catheter and connecting it to an underwater seal drain. However, you may first perform an emergency needle decompression. Where would you insert the decompression needle?

Answer 3

The preferred location for placement of a needle for aspiration of pneumothorax is the second intercostal space (between ribs 2 and 3) at the midclavicular line.

Neurovascular bundles are located at the lower edge of each rib. Therefore, the needle must be placed over the upper edge of the rib to avoid damage to the neurovascular bundle = Above the rib below = Above the 3rd rib to avoid Rib 2 nerves.

Insert the thoracostomy needle, piercing the skin over the rib below the target interspace, then directing the needle cephalad over the rib until the pleura is punctured (usually indicated by a pop and/or sudden decrease in resistance).

Question 4

What are the layers pierced when performing a needle decompression for a tension pneumothorax?

Answer 4

Aiming to get into intrapleural space

Question 5

What are the two sources of somatic innervation to the parietal pleura of the lungs?

Answer 5

The visceral pleura is insensitive to pain because it receives no nerves of general sensation.

The parietal pleura is extremely sensitive to pain. The parietal pleura is richly supplied by branches of the intercostal and phrenic nerves.

The parietal pleura receives somatic afferent (sensory) innervation from two different sources; the intercostal nerves (T1-T11) and the phrenic nerve (C3-C5). The intercostal nerves (T1-T11) provide innervation to the costal pleura and peripheral diaphragmatic pleura.

Referral of pain

• costal & peripheral pleura of the diaphragmatic pleura = dermatomes of thoracic and abdominal walls
• mediastinal and central diaphragmatic areas of parietal pleura results in referred pain to the root of the neck and over the shoulder

Question 6

List the three areas of unprotected pleura that are vulnerable to injury, as they are not covered by the bony thorax.

Answer 6

The anatomical protection of the pleural cavities is the bony thorax, which leaves three areas of vulnerability that may be clinically relevant in the setting of trauma to the lungs and pleura:

• (1) above the medial end of the first ribs
• (2) below the costal-xiphisternal angle on the right side,
• (3) below the costovertebral angles.