(a) The extrinsic ligaments of the larynx are those connecting the
thyroid cartilage and epiglottis with the hyoid bone and the cricoid cartilage with the
trachea. The intrinsic ligaments of the larynx are those connecting several cartilages of
the organ to each other. They are considered the elastic membrane of the larynx.
(b) The mucous lining of the larynx blends with the fibrous tissue to
form two folds on each side of the larynx. The upper set are known as the false cords.
The lower set are called the true vocal cords because they are primarily concerned with
the speaking voice and protection of the lower respiratory channels against the invasion
of food and foreign bodies.
(a) The laryngeal muscles perform two distinct functions. There are
muscles (extrinsic type) that open and close the glottis and those (intrinsic type) that
regulate the degree of tension of the vocal cords.
(b) It should be noted that the spoken voice also depends on the
sphincter action of the soft palate, tongue, and lips. The muscle action of the larynx
permits the glottis to close either voluntarily or involuntarily by reflex action. The closure
of the inlet by this mechanism protects the respiratory passages. The closure of the
glottis and the action of the vocal cords are precisely coordinated to produce the spoken
(c) Two branches of the vagus nerve supply the intrinsic muscles. The
recurrent laryngeal nerve branch of the vagus nerve is the important motor nerve of the
intrinsic muscles of the larynx. The sensory nerve, which is derived from the branches
of the superior laryngeal nerve, supplies the mucous membrane of the larynx.
(d) When both the recurrent laryngeal nerves become divided or
paralyzed, the glottis remains closed so tightly that air cannot be drawn into the lungs.
As a lifesaving measure, an endotracheal or tracheostomy tube is inserted immediately.
(e) The larynx derives its blood supply from the branches of the
external carotid and subclavian arteries.
e. Trachea. The trachea, a cylindrical tube about 15 cm in length and from 2 to
2.5 cm in diameter, begins in the neck and extends from the lower part of the larynx, on
a level with the sixth cervical vertebra, to the upper border of the fifth thoracic vertebra.
The tube descends in front of the esophagus, enters the superior mediastinum, and
divides into right and left main bronchi. The trachea is composed of a series of
incomplete rings of hyaline cartilage. The carina is a ridge on the inside at the
bifurcation of the trachea. It is a landmark during bronchoscopy and separates the
upper end of the right main branches from the upper end of the left main branches of