Laryngeal Anatomy

Question 1

Name the 4 intrinsic muscles of the larynx. Outline their action and innervation

Answer 1

Cricothyroid: Stretches and tenses the vocal cords. Superior laryngeal nerve (external branch) Thyrohyoid: Relaxes the vocal cords. Recurrent laryngeal nerve Posterior cricoarytenoid: Abducts the vocal cords. Recurrent laryngeal nerve Lateral cricoarytenoid: Adducts the vocal cords. Recurrent laryngeal nerve (Crazy Tigers Play Ludo)

Question 2

Draw the vocal cords and label the key features

Answer 2

Rima glottis, Rima vestibuli, vocal folds, vestibular folds, epiglottis

Question 3

State the vertebral level of the hyoid bone

Answer 3

C2/C3 in adults

Question 4

State the vertebral level of the cricoid cartilage

Answer 4

C6

Question 5

Describe the functions and boundaries of the nasal cavities, paranasal sinuses, pharynx (naso-, oro- and laryngo-) and larynx

Answer 5

Nasopharynx: Posterior nares - soft palate Oropharynx: Soft palate to epiglottis Layngopharynx: Epiglottis - C6 (cricoid cartilage) Paranasal sinuses: Function to add resonance to the voice, lighten head, warm, moisten and clean air. Vulnerable to infection spread from the nasal cavity via the respiratory epithelium. Nasal cavities: Warms and moistens air. Olfaction Larynx: Phonation at the vocal chords

Question 6

Describe the structure of the pharynx (muscles, fascia and mucosa) and its nerve supplies (sensory and motor) and function / movements.

Answer 6

Muscles: Constrictors (propel food) and longitudinal (elevate the pharynx and larynx during swallowing) Fascia: Muscoa: Pseudostratified ciliated squamous epithelium with goblet cells Sensory innervation: Vb, XI and X Motor innervation: All vagus (X) except stylopharyngeus which is innervated by the glossopharyngeal nerve

Question 7

Outline the structure and functions of the larynx and its key muscles.

Answer 7

Structure: Has 3 main cartilages (hyoid, thyroid and cricoid) Functions: Phonation, raises intraabdominal pressure, guards the entrance to tracheobronchial tree Key muscles: Intrinsic muscles (CTPL)

Question 8

Explain the consequence of damage to the nerves supplying the larynx, pharynx and nasal cavities (within this also explain pain referral patterns in the region).

Answer 8

Larynx: Can cause changes to the voice.

Question 9

Outline the sensory innervation and blood supply of the nasal cavity

Answer 9

Va and Vb with special olfactory innervation from CN I via the cribiform plate.

Has a very rich blood supply, originating from the external and internal carotid arteries.

Epistaxis may occur from the anastomoses

Question 10

Outline the sensory innervation of the paranasal air sinuses

Answer 10

All innervated by Va

• apart from the maxillary sinus which is innervated by Vb.

Respiratory mucosa lining.

Question 11

Outline the drainage of the paranasal air sinuses

Answer 11

Superior meatus: Drains the sphenoid and the posterior ethmoid sinus

Middle meatus: Drains the anterior and middle ethmoid, maxillary and frontal sinuses (via semilunar hiatus)

Inferior meatus: Drains the nasolacrimal duct

Question 12

Maxillary sinus drainage

Answer 12

Unable to drain with gravity, only drains when supine. This heightens the risk of infection.

Question 13

Soft palate: Function and control

Answer 13

Function: To prevent food from entering the nares

Control:

Tensor veli palatini - Tenses the soft palate

Levator veli palatini - Can then lift it to close the nasopharynx (CN X)

Palataglossus and palatopharyngeus can lower it to close the oral cavity

Question 14

Which nerves function in the gag reflex?

Answer 14

Motor: Vagus nerve CN X

Sensory: Glossopharyngeal nerve CN IX

Question 15

Outline the sensory innervation of the ear: Ectoderm, mesoderm and endoderm

Answer 15

• Ectoderm: Vc and X
  
  • Vc innervates the external acoustic meatus
• Mesoderm
• Endoderm: IX
  
  • Includes middle ear