Airway Anatomy

Question 1

What is the sensory innervation of the anterior tongue?

Answer 1

Trigeminal (V) V3 - mandibular branch

Question 2

What nerve innervates the posterior tongue?

Answer 2

Glossopharyngeal (IX)

Question 3

Which nerve is responsible for the sensory innervation of the soft palate?

Answer 3

Glossopharyngeal (IX)

Question 4

What nerve innervates the oropharynx?

Answer 4

Glossopharyngeal (IX)

Question 5

What is the sensory innervation of the vallecula?

Answer 5

Glossopharyngeal (IX)

Question 6

Which nerve provides sensory innervation to the anterior epiglottis?

Answer 6

Glossopharyngeal (IX)

Question 7

What nerve is responsible for the sensory innervation of the posterior epiglottis at the level of the vocal cords ?

Answer 7

Superior laryngeal internal branch (X)

Question 8

What innervates the laryngeal mucosa up to the level of the vocal cords?

Answer 8

Superior laryngeal internal branch (X)

Question 9

Which nerve innervates the laryngeal mucosa below the level of the vocal cords?

Answer 9

Recurrent laryngeal nerve

* footnote**

Part of the Vagus Nerve

Question 10

What nerve provides sensory innervation to the below the vocal cords/ trachea?

Answer 10

RLN of the Vagus (X)

Question 11

What are the two branches of the vagus nerve that provide innervation to the larynx?

Answer 11

The superior laryngeal nerve (SLN) internal branch and the recurrent laryngeal nerve.

The SLN has both an external and an internal branch.

Question 12

What does the external branch of the superior laryngeal nerve innervate?

Answer 12

The cricothyroid muscle.

This is the only muscle that tenses (elongates) the vocal cords.

Question 13

What is the function of the internal branch of the superior laryngeal nerve?

Answer 13

It is purely sensory.

Question 14

Which nerve innervates all of the other intrinsic laryngeal muscles?

Answer 14

The recurrent laryngeal nerve.

Question 15

Does the glossopharyngeal nerve innervate the larynx?

Answer 15

No, it does not innervate the larynx.

Question 16

What is the function of the posterior cricoarytenoid muscle?

Answer 16

The posterior cricoarytenoid is the only muscle that ABducts the vocal cords.

Question 17

What is the function of the cricothyroid muscle?

Answer 17

The cricothyroid is the only muscle that tenses (elongates) the vocal cords.

Question 18

What is the function of the aryepiglottic muscle?

Answer 18

The aryepiglottic closes the laryngeal vestibule.

Question 19

What is the function of the lateral cricoarytenoid muscle?

Answer 19

The lateral cricoarytenoid ADDucts the vocal cords.

Question 20

How does the right RLN differ from the left RLN?

Answer 20

The right RLN loops under the right subclavian artery, while the left RLN loops under the aorta.

This anatomical difference makes the left RLN more susceptible to injury.

Question 21

What are the causes of left RLN injury?

Answer 21

Causes of left RLN injury include: Mitral stenosis, PDA ligation, aortic arch aneurysm, and thoracic tumor.

Mitral stenosis may present as hoarseness due to left atrial enlargement compressing the nerve.

Question 22

What are the causes of RLN injury that can affect both sides?

Answer 22

Causes of left or right RLN injury include: parathyroid or thyroid surgery, external pressure from an LMA or ETT, neck tumor, and neck extension.

Question 23

How many cartilages make up the larynx?

Answer 23

The larynx consists of 9 cartilages (3 paired and 3 unpaired).

Question 24

What are the paired cartilages of the larynx?

Answer 24

The paired cartilages are corniculate, arytenoid, and cuneiform.

Question 25

What are the unpaired cartilages of the larynx?

Answer 25

The unpaired cartilages are epiglottis, thyroid, and cricoid.

Question 26

What is the trigeminal nerve (CN 5)?

Answer 26

The primary nerve that provides sensory innervation to the face and head.

Question 27

How many branches does the trigeminal nerve divide into?

Answer 27

It divides into 3 branches.

Question 28

What does V3 of the trigeminal nerve provide motor wise?

Answer 28

Motor innervation to muscles of mastication (chewing). ## Footnote It does not provide motor innervation to the tongue (tongue movement is a function of the hypoglossal nerve CN 12).

Question 29

What does V1 (Ophthalmic) sensory innervate?

Answer 29

Nares and anterior 1/3 of nasal septum.

Question 30

What does V2 (Maxillary) sensory innervate?

Answer 30

Turbinates and septum

Question 31

What does V3 (Mandibular) sensory innervate ?

Answer 31

Anterior 2/3 of the tongue.

Question 32

What is the glossopharyngeal nerve (CN 9) responsible for?

Answer 32

The glossopharyngeal nerve gives sensory innervation to the oropharynx and the anterior side of the epiglottis.

Question 33

What role does the glossopharyngeal nerve play in the gag reflex?

Answer 33

The glossopharyngeal nerve is the afferent limb of the gag reflex.

Question 34

What indicates inadequate anesthesia of the glossopharyngeal nerve during intubation?

Answer 34

If the patient gags during fiberoptic intubation, this indicates that the glossopharyngeal nerve was not adequately anesthetized.

Question 35

What areas does the glossopharyngeal nerve innervate?

Answer 35

The glossopharyngeal nerve innervates the soft palate, oropharynx, tonsils, posterior 1/3 of the tongue, vallecula, and the anterior side of the epiglottis. ***afferent limb of the gag reflex****

Question 36

What does the vagus nerve (CN 10) innervate?

Answer 36

SLN-> internal (posterior epiglottis) and external (cricothyroid) SLN RLN-> posterior epiglottis below cords/trachea and intrinsic m

Question 37

What are the branches of the vagus nerve related to the larynx?

Answer 37

The superior laryngeal nerve (internal and external branches) and the recurrent laryngeal nerves.

Question 38

What is the motor function of the internal branch of the superior laryngeal nerve?

Answer 38

0

Question 39

What is the sensory function of the internal branch of the superior laryngeal nerve?

Answer 39

Posterior side of epiglottis to the level of vocal cords.

Question 40

What is the motor function of the external branch of the superior laryngeal nerve?

Answer 40

Cricothyroid muscles (tense vocal cords).

Question 41

What is the sensory function of the external branch of the superior laryngeal nerve?

Answer 41

0

Question 42

What is the motor function of the recurrent laryngeal nerve?

Answer 42

All intrinsic laryngeal muscles EXCEPT cricothyroids.

Question 43

What is the sensory function of the recurrent laryngeal nerve?

Answer 43

Below level of vocal cords to trachea.

Question 44

What is the origin of the superior laryngeal nerve?

Answer 44

The superior laryngeal nerve branches off the vagus nerve just beyond the jugular foramen at the skull base.

Question 45

At what level does the superior laryngeal nerve divide?

Answer 45

At the level of the hyoid, it divides into the internal and external branches.

Question 46

Where does the internal branch of the superior laryngeal nerve penetrate?

Answer 46

The internal branch penetrates the thyrohyoid membrane between the greater cornu of the hyoid bone and the superior horn of the thyroid cartilage.

Question 47

Where do the recurrent laryngeal nerves branch off?

Answer 47

The recurrent laryngeal nerves branch off the vagus inside the thorax.

Question 48

How does the right recurrent laryngeal nerve travel?

Answer 48

The right RLN loops under the subclavian artery.

Question 49

How does the left recurrent laryngeal nerve travel?

Answer 49

The left RLN loops under the aortic arch.

Question 50

What is the path of both recurrent laryngeal nerves after looping under vascular structures?

Answer 50

Both nerves ascend the tracheoesophageal groove to join the larynx.

Question 51

Why is the left recurrent laryngeal nerve more susceptible to injury?

Answer 51

Due to its location in the thorax, as it loops under the aortic arch.

Question 52

What can cause RLN injury?

Answer 52

External pressure from ETT / LMA; Surgery: thyroid / parathyroid, Neck stretching, Neck tumor

Question 53

What are the causes of RLN Injury on the left side?

Answer 53

PDA ligation, Left atrial enlargement (mitral stenosis), Aortic arch aneurysm, Thoracic tumor

Question 54

What side of injury causes paralysis of the ipsilateral vocal cord abductors?

Answer 54

Unilateral injury causes paralysis of the ipsilateral vocal cord abductors.

Question 55

What is a symptom of unilateral RLN injury?

Answer 55

This causes hoarseness, but it does not cause respiratory distress (it is not an emergency).

Question 56

What is the most common nerve injury following subtotal thyroidectomy?

Answer 56

Unilateral RLN injury is the most common nerve injury following subtotal thyroidectomy.

Question 57

What happens to the affected cord during inspiration in unilateral RLN injury?

Answer 57

The affected cord is drawn to midline during inspiration.

Question 58

What causes bilateral paralysis of the vocal cord ABductors?

Answer 58

Bilateral injury causes bilateral paralysis of the vocal cord ABductors.

Question 59

What does acute injury favor in vocal cord function?

Answer 59

Acute injury favors a dangerous situation where the tensing action of the cricothyroid muscles acts unopposed.

Question 60

What are the symptoms of acute bilateral RLN injury?

Answer 60

This patient presents with stridor and respiratory distress (this is an emergency).

Question 61

What is the treatment for acute bilateral RLN injury?

Answer 61

Treatment includes emergent intubation or a surgical airway and paralyze

Question 62

How is chronic injury to the vocal cords typically tolerated?

Answer 62

Chronic injury is typically well tolerated.

Question 63

What happens during inspiration with bilateral RLN injury?

Answer 63

Both cords are drawn to midline during inspiration, leading to airway obstruction.

Question 64

Where should the needle be inserted for a glossopharyngeal nerve block?

Answer 64

At the base of the palatoglossal arch (anterior tonsillar pillar) to a depth of 0.25 - 0.5 cm.

Question 65

What does aspiration of air indicate during glossopharyngeal nerve block?

Answer 65

The needle is too deep.

Question 66

What should be done if blood is aspirated in glossopharyngeal nerve block?

Answer 66

Withdraw and redirect the needle medially, as the carotid artery is very close.

Question 67

What is the recommended volume of local anesthetic to inject glossopharyngeal nerve block?

Answer 67

1-2 mL of local anesthetic, repeated on the contralateral side.

Question 68

What is the incidence of intracarotid injection during the procedure?

Answer 68

There is a 5% incidence of intracarotid injection, which carries a risk of seizure.

Question 69

Where is the anesthetic injected for a superior laryngeal nerve block?

Answer 69

At the inferior border of the greater cornu of the hyoid bone.

Question 70

How much anesthetic is injected and where for superior laryngeal nerve block?

Answer 70

One mL is injected outside the thyrohyoid membrane, then 2 mL is injected 2-3 mm deep to the thyrohyoid membrane.

Question 71

What should be done after injecting on one side for superior laryngeal nerve block?

Answer 71

Repeat the procedure on the contralateral side.

Question 72

What does aspiration of air indicate during the procedure superior laryngeal nerve block?

Answer 72

It means that the needle is too deep.

Question 73

What is the first step in a recurrent laryngeal nerve block using the transtracheal approach?

Answer 73

Puncture the cricothyroid membrane, and advance the needle in a caudal direction. ## Footnote This reduces the risk of vocal cord injury.

Question 74

What should be done after aspiration but before injection during transtracheal procedure?

Answer 74

Tell the patient to take a deep breath.

Question 75

How much local anesthetic should be injected during inspiration transtracheal block?

Answer 75

Inject 3-5 mL of local anesthetic into the tracheal lumen.

Question 76

What is the expected reaction of the patient after the injection? For transtracheal block

Answer 76

The patient will cough, spraying the local anesthetic upwards through the cords.