The larynx is a hollow fibrocartilaginous organ of the upper respiratory tract located between the pharynx and trachea. It plays a key role in phonation, respiration, and protection of the lower airway.

At which vertebral levels is the larynx located?

The larynx extends from the level of the C3 to C6 vertebrae in adults.

What are the main functions of the larynx?

The main functions of the larynx are voice production, maintenance of a patent airway for breathing, prevention of aspiration during swallowing, and initiation of the cough reflex.

How many cartilages form the larynx?

The larynx is formed by nine cartilages: three unpaired (thyroid, cricoid, epiglottis) and three paired (arytenoid, corniculate, and cuneiform).

Which cartilage forms a complete ring in the larynx?

The cricoid cartilage is the only laryngeal cartilage that forms a complete ring around the airway.

What are the main parts of the laryngeal cavity?

The laryngeal cavity is divided into the vestibule, ventricle, and infraglottic cavity.

What is the difference between true and false vocal cords?

True vocal cords are involved in phonation and contain the vocal ligament, while false vocal cords (vestibular folds) are primarily protective and do not produce sound.

Which muscle is the only abductor of the vocal cords?

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

What is the nerve supply of the larynx?

Motor supply is mainly by the recurrent laryngeal nerve, except the cricothyroid muscle which is supplied by the external laryngeal nerve. Sensory supply above the vocal cords is via the internal laryngeal nerve and below the cords via the recurrent laryngeal nerve.

What is the function of the epiglottis?

The epiglottis prevents food and liquids from entering the larynx during swallowing by directing them toward the esophagus.

Why do vocal cord tumors present early with hoarseness?

Vocal cord tumors affect cord vibration even when small, leading to early hoarseness due to disruption of normal phonation.

What is the clinical importance of the cricothyroid membrane?

The cricothyroid membrane is the preferred site for emergency airway access during cricothyrotomy.

What happens in unilateral recurrent laryngeal nerve injury?

Unilateral recurrent laryngeal nerve injury typically causes hoarseness of voice due to paralysis of one vocal cord.

What happens in bilateral recurrent laryngeal nerve injury?

Bilateral injury causes paralysis of both vocal cords in a near-midline position, leading to severe airway obstruction and stridor.

Why is lymphatic spread limited in glottic cancers?

Glottic cancers spread late because the true vocal cords have very poor lymphatic drainage.

Larynx Anatomy Functions Nerve Supply Muscles Cartilages Clinical Importance

Larynx

Definition

The larynx is a hollow, fibrocartilaginous organ of the upper respiratory tract located in the anterior neck opposite C3–C6 vertebrae. It connects the laryngopharynx to the trachea and is essential for phonation, respiration, and protection of the lower airway.

Functions

Phonation – production and modulation of voice
Respiration – maintains a patent airway
Airway protection – prevents aspiration during swallowing
Cough reflex – expulsion of foreign bodies

Development

Develops from the laryngotracheal diverticulum (endoderm)
Cartilages and muscles arise from 4th and 6th pharyngeal arches
Epiglottis develops from 3rd and 4th arches

External Features

Laryngeal prominence (Adam’s apple) – prominent in males
Thyroid notch
Cricothyroid membrane – important for emergency airway access

Framework of Larynx

Laryngeal Cartilages

Unpaired (3)

Thyroid cartilage

* Largest cartilage, two laminae forming laryngeal prominence

* Superior and inferior horns (cornua)

Cricoid cartilage

* Complete ring (signet-ring shaped)

* Only complete cartilaginous ring in airway

* Lies at C6 level

Epiglottis

* Leaf-shaped elastic cartilage

* Prevents food entering airway during swallowing

Paired (3)

Arytenoid cartilages

* Pyramidal, sit on cricoid lamina

* Vocal process (vocal ligament attachment)

* Muscular process (muscle attachment)

Corniculate cartilages

* Sit on arytenoids

* Support aryepiglottic folds

Cuneiform cartilages

* Embedded in aryepiglottic folds

* Provide structural support

Joints of Larynx

Cricothyroid joint

* Rotation and gliding

* Alters pitch by tensing vocal cords

Cricoarytenoid joint

* Sliding and rotation

* Abduction and adduction of vocal cords

Ligaments and Membranes

Thyrohyoid membrane – connects larynx to hyoid
Cricothyroid membrane – access point for cricothyrotomy
Quadrangular membrane – forms vestibular folds
Conus elasticus – forms vocal ligaments

Cavity of Larynx

Divisions

Vestibule

* From laryngeal inlet to vestibular folds

Ventricle

* Space between vestibular and vocal folds

* Contains saccule (lubricates vocal cords)

Infraglottic cavity

* From vocal folds to lower border of cricoid

Laryngeal Inlet (Aditus)

Anterior – epiglottis
Posterior – interarytenoid fold
Lateral – aryepiglottic folds

Folds of Larynx

Vestibular folds (false cords) – protective, no phonation
Vocal folds (true cords) – phonation

* Stratified squamous epithelium

* White due to avascularity

Muscles of Larynx

Extrinsic Muscles

Move larynx up or down

Elevators

Digastric
Stylohyoid
Mylohyoid
Geniohyoid

Depressors

Sternohyoid
Sternothyroid
Thyrohyoid
Omohyoid

Intrinsic Muscles

Control vocal cord movement

| Muscle | Action |

| ------------------------------- | -------------------------------- |

| Posterior cricoarytenoid | Only abductor of vocal cords |

| Lateral cricoarytenoid | Adduction |

| Transverse & oblique arytenoids | Adduction |

| Cricothyroid | Tenses cords (raises pitch) |

| Thyroarytenoid | Relaxes cords (lowers pitch) |

| Vocalis | Fine tuning of voice |

Nerve Supply (Vagus Nerve)

Motor

Recurrent laryngeal nerve (all intrinsic muscles except one)
External laryngeal nerve → Cricothyroid

Sensory

Internal laryngeal nerve – above vocal cords
Recurrent laryngeal nerve – below vocal cords

Blood Supply

Arteries

Superior laryngeal artery (from superior thyroid artery)
Inferior laryngeal artery (from inferior thyroid artery)

Veins

Superior and inferior laryngeal veins → thyroid venous plexus

Lymphatic Drainage

Above vocal cords → Upper deep cervical nodes
Below vocal cords → Lower deep cervical nodes
Vocal cords themselves have poor lymphatic drainage

Surface Anatomy

Upper border: opposite C3
Lower border: opposite C6
Moves upward during swallowing

Applied Anatomy

Hoarseness – vocal cord pathology or recurrent laryngeal nerve injury
Bilateral recurrent laryngeal nerve injury – airway obstruction
Unilateral injury – hoarseness
Cricothyrotomy – emergency airway access
Laryngeal carcinoma – early hoarseness (glottic tumors)

Larynx Anatomy Functions Nerve Supply Muscles Cartilages Clinical Importance