LARYNX

The larynx is a cartilaginous structure located in the neck, situated below the hyoid bone and above the trachea. It plays a crucial role in voice production, protecting the airway, and swallowing.

• The larynx is a vital structure for voice production, respiration, and swallowing.

• It is composed of cartilaginous and connective tissue.

• The larynx is divided into three main parts: the epiglottis, the glottis, and the subglottis.

• The epiglottis is a leaf-shaped cartilage that separates the trachea from the esophagus.

• The glottis is the opening between the vocal folds.

• The subglottis is the area below the glottis.

• The larynx is innervated by the vagus nerve (CN X) and the recurrent laryngeal nerve.

• The blood supply to the larynx comes from the superior and inferior laryngeal arteries.

• The lymphatic drainage of the larynx is through the deep cervical lymph nodes.

• Cartilages of larynx:

  • Thyroid cartilage: largest cartilage of larynx
  • Cricoid cartilage: ring-shaped cartilage below thyroid cartilage
  • Epiglottis: leaf-shaped cartilage at the top of larynx
  • Arytenoid cartilages: two small cartilages that support vocal cords
  • Corniculate cartilages: small cartilages attached to arytenoid cartilages
  • Cuneiform cartilages: small cartilages attached to arytenoid cartilages

• Interior of larynx:

  • Passages:
    • Nasopharynx (above larynx)
    • Laryngopharynx (below larynx)
    • Trachea (below larynx)
  • Vocal cords: two bands of mucous membrane that vibrate to produce sound
  • Laryngeal prominence: bony projection of thyroid cartilage
  • Laryngeal ventricle: space between vocal cords and false vocal cords
  • True vocal cords: bands of mucous membrane that vibrate to produce sound
  • False vocal cords: two bands of mucous membrane above true vocal cords

• Blood supply of larynx:

  • Internal carotid artery: supplies blood to upper part of larynx
  • External carotid artery: supplies blood to lower part of larynx
  • Superior laryngeal artery: branch of internal carotid artery
  • Inferior laryngeal artery: branch of external carotid artery

• Nerve supply of larynx:

  • Superior laryngeal nerve: branch of vagus nerve
  • Recurrent laryngeal nerve: branch of vagus nerve
  • Internal laryngeal nerve: branch of superior laryngeal nerve
  • External laryngeal nerve: branch of superior laryngeal nerve Developmental Process:

• The larynx develops from the fifth pharyngeal arch.

• The epiglottis develops from the sixth pharyngeal arch.

• The vocal folds develop from the endoderm of the laryngeal diverticulum.

• The larynx descends during development to its final position in the neck.

Muscle Action Sequence:

• The cricothyroid muscle contracts to stretch the vocal folds.

• The thyroid muscle contracts to lengthen the vocal folds.

• The posterior cricoarytenoid muscle contracts to open the glottis.

• The arytenoid muscle contracts to close the glottis.

• Applied anatomy:

  • Laryngoscopy: examination of larynx with a laryngoscope
  • Tracheostomy: surgical incision into trachea
  • Laryngeal nerve block: block of nerve supply to larynx for surgical procedures
  • Vocal cord paralysis: paralysis of vocal cords due to injury or disease
  • Laryngeal cancer: cancer of larynx