1 Anatomy

The larynx is a complex structure of cartilage, membrane, muscle, and mucosa located in the anterior neck. It forms the passage between the pharynx and the trachea and houses the vocal folds, which are central to voice production. In addition to phonation, the larynx contributes to breathing and helps protect the lower airway during swallowing.

1.1 Gross structure

The larynx lies in front of the lower pharynx and above the trachea. It is suspended from the hyoid bone and extends downward to the upper end of the trachea. Externally, it is often described as having a framework of cartilages joined by ligaments and moved by intrinsic muscles. Internally, its mucosal lining creates a cavity through which air passes.

1.2 Cartilages of the larynx

The laryngeal framework is formed by several cartilages that give the organ shape and support. Some are large and easily identified, while others are smaller and serve specialized roles in opening, closing, and adjusting the vocal folds.

1.2.1 Thyroid cartilage

The thyroid cartilage is the largest laryngeal cartilage and forms the main anterior and lateral walls of the larynx. Its two broad plates meet in the midline to create the laryngeal prominence, commonly called the Adam’s apple. It serves as an attachment site for ligaments and muscles that influence vocal fold position.

1.2.2 Cricoid cartilage

The cricoid cartilage is the only complete ring of cartilage in the airway. It lies below the thyroid cartilage and above the trachea, providing a stable base for laryngeal movement. Its broad posterior portion supports the arytenoid cartilages and contributes to the mechanics of vocal fold motion.

1.2.3 Epiglottis

The epiglottis is a leaf-shaped cartilage that projects upward behind the tongue. During swallowing, it helps direct food and liquid away from the laryngeal inlet. Its flexible structure and attachment to surrounding tissues allow it to move as part of airway protection.

1.2.4 Arytenoid cartilages

The arytenoid cartilages are paired, pyramid-shaped structures situated on the posterior cricoid cartilage. They are essential for vocal fold movement because they serve as attachment points for many intrinsic muscles. Their rotation and sliding motions alter the opening, tension, and position of the vocal folds.

1.3 Ligaments and membranes

Ligaments and membranes connect the cartilages and help maintain the shape of the larynx. The thyrohyoid membrane links the larynx to the hyoid bone, while the cricothyroid and conus elasticus structures contribute to the support of the vocal folds. These connective tissues also help define spaces within the laryngeal cavity.

1.4 Intrinsic muscles

The intrinsic muscles of the larynx control the position and tension of the vocal folds. Some muscles open the glottis for breathing, whereas others close it or adjust its length and tension for speech and swallowing. Coordinated activity among these muscles is necessary for precise laryngeal function.

1.5 Laryngeal cavity

The laryngeal cavity is the internal space of the larynx. It is divided into regions that guide airflow and create the anatomy needed for sound production and airway protection.

1.5.1 Inlet

The laryngeal inlet is the upper opening of the larynx, connecting it to the pharynx. It is bordered by the epiglottis, aryepiglottic folds, and arytenoid region. The inlet is important for directing material into the esophagus rather than the airway during swallowing.

1.5.2 Vestibule

The vestibule is the upper portion of the laryngeal cavity, extending from the inlet to the vestibular folds. It acts as a passageway for air and contributes to the overall shape of the airway.

1.5.3 Ventricles

The laryngeal ventricles are small recesses located between the vestibular folds and the vocal folds. They contain mucous glands that help lubricate the vocal folds, which is important for smooth vibration during phonation.

1.5.4 Glottis

The glottis includes the vocal folds and the opening between them. It is the most functionally significant part of the larynx for voice production. The degree of glottic opening changes continuously during breathing, speech, coughing, and swallowing.

1.6 Blood supply and lymphatic drainage

The larynx receives blood from branches of the superior and inferior thyroid arteries. Venous drainage follows corresponding veins. Lymphatic drainage varies by region, with the upper larynx draining more broadly and the lower larynx tending toward deeper cervical nodes. This pattern is clinically important in the spread of disease.

1.7 Nerve supply

The larynx is supplied by branches of the vagus nerve. The superior laryngeal nerve provides sensory and motor fibers to different laryngeal structures, while the recurrent laryngeal nerve supplies most intrinsic muscles and much of the sensory innervation below the vocal folds. This nerve supply is essential for both movement and protective sensation.

2 Development

The larynx develops early in embryonic life and continues to change after birth. Its development involves the formation of the cartilage framework, the recanalization of the airway, and the maturation of motor control and voice function.

2.1 Embryology

The larynx arises from the foregut region of the embryo, with contributions from pharyngeal arch structures. The lining epithelium, cartilages, muscles, and nerves develop in coordinated stages. Early in development, the laryngeal lumen becomes temporarily narrowed and later opens again, establishing the airway passage.

2.2 Postnatal growth and maturation

After birth, the larynx grows in size and changes in shape. In infancy and childhood it is positioned higher in the neck, which supports efficient feeding and breathing. During puberty, especially in males, growth of the laryngeal framework lengthens and lowers the voice, producing a deeper pitch.

3 Physiology

The larynx performs several overlapping functions that depend on the precise interaction of cartilage, muscle, airflow, and mucosal vibration. Its role extends beyond speech to include respiration and airway defense.

3.1 Respiration

During quiet breathing, the vocal folds are positioned apart to allow air to move freely between the pharynx and trachea. The larynx helps regulate airway resistance and can widen or narrow the glottic opening according to respiratory demand. This control becomes especially important during exercise or airway stress.

3.2 Phonation

Voice production occurs when exhaled air causes the vocal folds to vibrate. Pitch, loudness, and quality are influenced by vocal fold length, tension, mass, and the size of the glottic opening. Resonance from the pharynx, mouth, and nasal cavities then shapes the final sound of speech.

3.3 Swallowing and airway protection

During swallowing, the larynx elevates and the vocal folds close to protect the airway. The epiglottis and surrounding structures help guide food and liquid away from the trachea. This coordinated action reduces the risk of aspiration and is essential for safe feeding.

3.4 Cough reflex

The larynx is central to the cough reflex, which clears material from the airway. Sensory input from the laryngeal mucosa can trigger a forceful expulsion of air after brief glottic closure. This mechanism helps protect the lower respiratory tract from foreign particles and secretions.

4 Clinical examination

Assessment of the larynx combines history, physical examination, visualization, and imaging. Because many laryngeal disorders affect voice and breathing, symptom pattern and duration are often important clues.

4.1 History and symptoms

Common symptoms include hoarseness, throat discomfort, cough, shortness of breath, noisy breathing, and swallowing difficulty. Patients may also report voice fatigue, reduced vocal range, or a sensation of a lump in the throat. The clinical history helps distinguish irritation, structural disease, neurologic dysfunction, and more serious lesions.

4.2 Physical examination

Examination may include inspection of the neck, assessment of breathing, and evaluation of the voice. Clinicians look for signs of respiratory distress, tenderness, neck masses, or abnormal phonation. A focused exam can suggest whether the problem is inflammatory, mechanical, neurologic, or neoplastic.

4.3 Laryngoscopy

Laryngoscopy is the principal method for directly viewing the larynx. It allows examination of the vocal folds, mucosal surface, and movement during breathing and phonation.

4.3.1 Indirect laryngoscopy

Indirect laryngoscopy uses a small mirror placed in the oropharynx to visualize the larynx. Although less commonly used than newer techniques, it remains a simple office-based method in selected situations.

4.3.2 Flexible fiberoptic laryngoscopy

Flexible fiberoptic laryngoscopy is performed with a thin scope passed through the nose. It provides detailed views of laryngeal structure and function while the patient breathes, speaks, and swallows. This technique is widely used because it is well tolerated and can be done without general anesthesia.

4.3.3 Direct laryngoscopy

Direct laryngoscopy uses rigid instruments, usually under anesthesia, to obtain a close view of the larynx. It is useful when biopsy, detailed inspection, or treatment is needed. This approach is also important in airway management and certain surgical procedures.

4.4 Imaging studies

Imaging may be used to assess masses, cartilage invasion, airway narrowing, or extension beyond the larynx. Computed tomography and magnetic resonance imaging are especially helpful for structural evaluation. Imaging complements endoscopic findings rather than replacing them.

5 Disorders of the larynx

Laryngeal disorders range from temporary inflammation to chronic structural and malignant conditions. They may affect voice, breathing, swallowing, or a combination of these functions.

5.1 Inflammatory conditions

Inflammatory disorders often cause hoarseness, throat pain, or a sensation of irritation. They may arise from infection, strain, environmental exposure, or irritation from stomach contents.

5.1.1 Laryngitis

Laryngitis is inflammation of the laryngeal mucosa, commonly associated with viral infection, voice overuse, or irritation. Symptoms often include hoarseness and reduced voice quality. Most cases are self-limited, but persistent symptoms may require further evaluation.

Reflux-related irritation occurs when gastric contents reach the laryngeal area and inflame the mucosa. Patients may experience chronic throat clearing, hoarseness, cough, or a globus sensation. The condition can resemble other causes of voice disturbance, so diagnosis often depends on clinical assessment.

5.2 Structural and functional disorders

These disorders involve impaired movement, narrowing, or altered mechanics of the larynx. They may significantly affect breathing and voice.

5.2.1 Vocal fold paralysis

Vocal fold paralysis results from loss of motion in one or both vocal folds, often due to nerve injury. Unilateral paralysis can cause breathy voice and weak cough, while bilateral involvement may lead to airway compromise. Management depends on severity and cause.

5.2.2 Laryngeal stenosis

Laryngeal stenosis is narrowing of the laryngeal airway. It may follow trauma, prolonged intubation, inflammation, or congenital factors. Symptoms can include noisy breathing, exertional dyspnea, and voice changes.

5.2.3 Laryngeal webs and cysts

Laryngeal webs are thin tissue bands that partially obstruct the airway or alter vocal fold function. Cysts are fluid-filled or mucus-filled lesions that may affect voice quality if they involve the vocal folds. Both can produce hoarseness and may require surgical treatment when symptomatic.

5.2.4 Voice disorders

Voice disorders involve abnormal pitch, loudness, quality, or endurance of phonation. They may arise from misuse, structural lesions, muscle tension, neurologic problems, or inflammatory conditions. Evaluation often includes both medical and speech-language assessment.

5.3 Benign lesions

Benign laryngeal lesions commonly affect the vocal folds and are often related to repeated mechanical stress. They usually present with persistent hoarseness rather than airway symptoms.

5.3.1 Nodules

Vocal fold nodules are small, usually bilateral growths that develop at sites of repetitive vocal trauma. They are common in people with heavy voice use. Treatment often emphasizes voice modification and therapy.

5.3.2 Polyps

Vocal fold polyps are localized benign lesions that may be associated with acute or chronic vocal strain. They are often unilateral and can cause breathiness, roughness, or vocal fatigue. Some improve with conservative care, while others require removal.

5.3.3 Papillomas

Laryngeal papillomas are wart-like growths caused by infection with human papillomavirus. They may recur and can interfere with voice or breathing depending on size and location. Management often involves repeated endoscopic removal.

5.4 Malignant tumors

Malignancies of the larynx are important because they can present with persistent hoarseness, swallowing difficulty, or airway symptoms. Early recognition improves the chance of successful treatment.

5.4.1 Laryngeal cancer

Laryngeal cancer most often arises from the mucosal lining of the glottic or supraglottic regions. It may cause hoarseness, throat discomfort, dysphagia, or neck mass. Treatment may involve surgery, radiation, chemotherapy, or combined approaches depending on stage and site.

5.4.2 Risk factors and staging

Major risk factors include tobacco exposure, alcohol use, and chronic irritation of the mucosa. Staging is based on tumor size, local extension, nodal involvement, and distant spread. Accurate staging guides prognosis and treatment planning.

6 Treatment and management

Management of laryngeal conditions depends on the underlying disorder, severity of symptoms, and effect on airway, voice, and swallowing. Treatment may be conservative, rehabilitative, procedural, or surgical.

6.1 Medical therapy

Medical treatment can include anti-inflammatory measures, antibiotics when indicated, reflux management, and therapies aimed at reducing edema or irritation. In acute conditions, rest and avoidance of aggravating factors may also be recommended. Medical care is often combined with diagnostic surveillance.

6.2 Voice therapy

Voice therapy is directed by speech-language specialists and focuses on improving vocal technique, reducing strain, and promoting efficient phonation. It is commonly used for nodules, functional voice disorders, and recovery after certain laryngeal injuries. Therapy may also support long-term vocal health in professional voice users.

6.3 Surgical treatment

Surgery is considered when there is airway compromise, persistent structural disease, significant lesions, or cancer requiring removal. Procedures are tailored to preserve function whenever possible.

6.3.1 Microlaryngoscopic procedures

Microlaryngoscopic procedures are performed with magnification and delicate instruments to remove or sample lesions of the vocal folds. They are used for nodules, polyps, cysts, papillomas, and biopsy of suspicious tissue. Precision is important because even minor trauma can affect voice quality.

6.3.2 Airway surgery

Airway surgery addresses narrowing or obstruction of the larynx and may include dilation, scar removal, or tracheostomy in severe cases. The primary goal is to maintain a safe and adequate airway. Such procedures may be urgent when breathing is threatened.

6.3.3 Laryngeal reconstruction

Laryngeal reconstruction is used to restore structure and function after injury, stenosis, or tumor removal. Techniques vary from local tissue repair to more extensive reconstructive approaches. The aim is to balance breathing, swallowing, and voice preservation.

6.4 Rehabilitation and follow-up

Follow-up is important after treatment because laryngeal disorders can recur or leave lasting functional changes. Rehabilitation may include repeat voice assessment, swallowing evaluation, and monitoring for airway issues. Long-term care often involves cooperation among otolaryngology, speech therapy, and other supportive services.

7 Special topics

Certain laryngeal issues require attention to age, occupation, recovery from surgery, or voice replacement methods. These topics highlight the larynx’s role in everyday communication and airway function.

7.1 Pediatric larynx

The pediatric larynx differs from the adult larynx in size, position, and vulnerability to swelling. Because the airway is smaller, even modest inflammation can cause significant obstruction. Children may also present with congenital anomalies that affect breathing or voice.

7.2 Occupational voice use

People who rely heavily on the voice, such as teachers, singers, actors, and public speakers, are especially prone to overuse injuries. Efficient technique, hydration, rest, and training in vocal hygiene help reduce strain. Early evaluation of persistent hoarseness is important in this group.

7.3 Postoperative care

After laryngeal surgery, care often includes voice rest, pain control, airway observation, and gradual return to vocal activity. Patients may need instruction on swallowing safety and wound care. Follow-up examinations assess healing and functional outcome.

7.4 Artificial larynx and voice restoration

Artificial larynx devices and other voice restoration methods help individuals who cannot use the natural larynx effectively. These approaches may be used after removal of the larynx or in severe voice loss. Restoration strategies can include electrolarynx devices, esophageal speech training, and surgically assisted voice replacement.