Page 877 - Fundamentals of anatomy physiology

864 Unit 5 Environmental Exchange
Figure 23–4 The Anatomy of the Larynx.

Epiglottis Epiglottis Hyoid bone
Lesser cornu
Hyoid bone Vestibular Thyroid
ligament cartilage
Thyrohyoid Corniculate Corniculate
ligament cartilage cartilage
Vocal ligament
Larynx Laryngeal Arytenoid Cricoid
Trachea prominence cartilage cartilage
Cricothyroid ligament Tracheal
Thyroid Cricotracheal ligament cartilages
cartilage POSTERIOR
ANTERIOR
Cricothyroid
ligament
Cricoid cartilage
Cricotracheal
ligament

Tracheal
cartilages

a Anterior view b Posterior view c Sagittal section

23 this ligament is a common placement site for an emergency related to the size of your larynx. You control the tension by
tracheostomy, a tracheal incision to bypass an airway obstruc- contracting voluntary muscles that reposition the arytenoid
tion. The vestibular ligaments and the vocal ligaments extend cartilages relative to the thyroid cartilage. When the distance
between the thyroid cartilage and the arytenoid cartilages. increases, your vocal folds tense and the pitch rises. When the
distance decreases, your vocal folds relax and the pitch falls.
The vestibular and vocal ligaments are covered by folds
of laryngeal epithelium. The vestibular ligaments lie within Children have slender, short vocal folds, so their voices
the superior pair of folds, known as the vestibular folds tend to be high-pitched. At puberty, the larynx of males en-
(Figure 23–5). These folds are fairly inelastic and lie laterally larges much more than does that of females. The vocal cords of
to the glottis. The glottis (GLOT-is) is made up of the vocal an adult male are thicker and longer. They produce lower tones
folds and the space between them, called the rima glottidis than those of an adult female.
(Figure 23–5). The vestibular folds help prevent foreign objects
from entering the open glottis. They also protect the more infe- Sound production at the larynx is called phonation (fo. -NA. -
rior, delicate vocal folds of the glottis. shun; phone, voice). Phonation is one part of speech produc-
tion. Clear speech also requires articulation, the modification
The vocal folds are highly elastic, because the vocal liga- of those sounds by other structures, such as the tongue, teeth,
ments consist of elastic tissue. The vocal folds are involved with and lips to form words. In a stringed instrument, such as a gui-
the production of sound. For this reason they are known as the tar, the quality of the sound produced does not depend solely
vocal cords. on the nature of the vibrating string. Rather, the entire instru-
ment becomes involved as the walls vibrate and the composite
Sound Production sound echoes within the hollow body. Similar amplification
and resonance take place within your pharynx, oral cavity,
How do you produce sounds? Air passing through your open nasal cavity, and paranasal sinuses. The combination gives you
glottis vibrates its vocal folds and produces sound waves. The the particular and distinctive sound of your voice. That sound
pitch of the sound depends on the diameter, length, and ten- changes when you have a sinus infection and your nasal cavity
sion in your vocal folds. The diameter and length are directly and paranasal sinuses are filled with mucus rather than air.