Nerves Associated with Respiration (AP)

Question 1

2 branches of vagus nerve innervating larynx

Answer 1

• Superior laryngeal nerve
• Recurrent laryngeal nerve

Question 2

2 branches of superior laryngeal nerve, and what each provides to where

Answer 2

• Internal branch = sensory to laryngeal cavity above folds
• External branch = motor to cricothyroid

Question 3

What does the recurrent laryngeal nerve provide to where?

Answer 3

• Sensory to laryngeal cavity below folds + trachea
• Motor to intrinsic laryngeal muscles except cricothyroid

Question 4

Motor and sensory functions of phrenic nerve

Answer 4

• M = innervate diaphragm
• S = innervate central tendon of diaphragm

Question 5

When/where is the phrenic nerve prone to injury?

Answer 5

• Cardiac surgery
• Removal of lung/mediastinum tumour
• Neck (stabbing injury)

Question 6

What does injury to the diaphragm result in?

Answer 6

Paradoxical movement of the diaphragm

Question 7

Where do intercostal nerves arise?

Answer 7

Ventral rami of spinal nerves T1-11

Question 8

Motor function of intercostal nerves

Answer 8

Innervate intercostal + abdominal wall muscles

Question 9

Sensory branches of intercostal nerves and what they provide to

Answer 9

• Lateral cutaneous nerve = somatic sensation of skin (lateral body)
• Anterior cutaneous nerve = somatic sensation of skin (front of body)
• Sensory branches to parietal pleura/peritoneum = somatic sensation
• Branch to peripheral diaphragm (T6-11) = sensation

Question 10

Which muscles does the intercostal neurovascular bundle lie between?

Answer 10

Internal + innermost intercostals

Question 11

What is thoracentesis and when is it needed?

Answer 11

• Needle inserted into plural space
• Pleural effusion

Question 12

Where does a needle need to be placed in relation to the rib in thoracentesis and why?

Answer 12

• Over the rib
• Avoids neurovascular bundle –> otherwise nerve damaged

Question 13

What happens when the intercostal nerve is damaged?

Answer 13

• Muscles loses motor innervation
• Will be drawn in on inspiration + pushed out on expiration

Question 14

What is pleuritic pain?

Answer 14

Localised, sharp stabbing made worse on deep inspiration, coughing or movement

Question 15

What causes pleuritic pain?

Answer 15

Viral or bacterial infection

Question 16

Muscles involved in quiet inspiration and their innervation

Answer 16

• Diaphragm = phrenic (C3-5)

Question 17

Muscles involved in forced inspiration and their innervation

Answer 17

• Diaphragm = phrenic (C3-5)
• External intercostals = intercostal nerves (T1-11)
• Scalene = anterior rami spinal nerves C3-8
• Sternocleidomastoid = CNXI + C2-3 branches

Question 18

Muscles involved in forced expiration and their innervation

Answer 18

• Internal intercostals = intercostal nerves (T1-11)
• Rectus abdominis = intercostal nerves (T6-11) + subcostal nerve (T12)
• Transversus abdominis = intercostal nerves (T7-11) + subcostal nerve (T12) + lumbar plexus branches

Question 19

How do the sneeze/cough reflexes work?

Answer 19

• Irritation of larynx/trachea
• Impulses from laryngeal branches of vagus –> trigeminal sensory nucleus (brainstem)
• Impulses to medullary respiratory centres –> nucleus ambiguous
• Impulses to intercostal + abdominal walls after build up of pressure against closed glottis