Airway Anatomy

Pharyngeal-laryngeal muscles:

• Pharyngeal muscles: Constrictors, longitudinal

• Laryngeal muscles are intrinsic and extrinsic 

Larynx

The larynx is a cartilaginous organ, the gateway between the upper and lower airways and plays a critical role in voice production. It is suspended from the hyoid bone.

There are 9 laryngeal cartilages:

Single (3)

1. Thyroid cartilage

2. Cricoid cartilage

3. Epiglottis

Paired (6)

1. Arytenoid (2)

2. Corniculate (2)

3. Cuneiform (2)

Joints (allow movement of the vocal folds)

1. Cricothyroid joint

2. Cricoarytenoid joint

Muscles

1. Extrinsic muscles: Move the entire larynx during swallowing.

2. Intrinsic muscles: Control the vocal folds and glottis.

Cavities

1. Laryngeal inlet

2. Vestibule

3. Vestibular folds (false vocal cords)

4. Ventricle

5. Vocal folds (true vocal cords)

6. Glottis

7. Subglottic region

Laryngeal Muscles

1. Extrinsic Laryngeal Muscles (Move the entire larynx)

Elevators

1. Digastric

2. Stylohyoid

3. Mylohyoid

4. Geniohyoid

5. Stylopharyngeus

6. Palatopharyngeus

7. Salpingopharyngeus

Depressors

8. Sternohyoid

9. Omohyoid

10. Sternothyroid

11. Thyrohyoid

2. Intrinsic Laryngeal Muscles ( control the vocal cords): 

All intrinsic muscles are supplied by the recurrent laryngeal nerve except the cricothyroid (external branch of the superior laryngeal nerve, the muscle responsible for increased pitch)

Abductor (Opens the Airway)

Posterior cricoarytenoid

Adductors (Close the Airway)

1. Lateral cricoarytenoid

2. Transverse arytenoid

3. Oblique arytenoid

Posterior cricoarytenoid opens the glottis; the arytenoid muscles close it for airway protection; cricothyroid and thyroarytenoid adjust vocal cord tension for phonation

Cricothyrotomy:

Indication: Can't Intubate, Can't Oxygenate (CICO)

Children <8–10 years -> needle cricothyrotomy preferred