Download Role of Tonsils and Larynx in defence and phonation

Role of Tonsils and Larynx in defence and phonation
Tonsils
Lecture outline
Types
Palatine
Nasopharyngeal or Adenoids
Lingual
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Palatine Tonsils
Palatine tonsils are two clumps of tissue located at entrance to the upper respiratory and
gastrointestinal tract
Lies on either side of throat , the lower edge of each tonsils is beside the tongue
Adenoids
Mass of lymphoid tissue situated at the very back of the nose, in the roof of the
nasopharynx, where the nose blends into the mouth.
Lingual tonsils
 Present on the dorsal surface at the base of the tongue.
 Their lymphatic tissue are dense and nodular, their surface is covered with
stratified squamous epithelium which invaginates as a single crypt into each
lingual tonsil.
 They have associated mucous glands which are drained by ducts directly into the
single tonsillar crypt.
Tonsils
Functions
1. Monitors the quality of air,food and water which enter our body
2. Play a major role in body immunity mechanism and produce all five antibodies.
3. Becomes red swollen mass indicating infection entering in body
4. Traps micro organisms that enter the body and drains into lymph for elimination
5. In addition to humoral immunity there is considerable T cell response also
Larynx (voice box)
 Larynx is a short, somewhat cylindrical airway ends in the trachea.
 Prevents swallowed materials from entering the lower respiratory tract.
 Conducts air into the lower respiratory tract.
 Produces sounds.
 Supported by a framework of nine pieces of cartilage (three individual pieces and three
cartilage pairs) that are held in place by ligaments and muscles.
Larynx
Nine c-rings of cartilage form the framework of the larynx
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thyroid cartilage – (1) Adam’s apple, hyaline, anterior attachment of vocal folds, testosterone
increases size after puberty
cricoid cartilage – (1) ring-shaped, hyaline
arytenoid cartilages – (2) hyaline, posterior attachment of vocal folds,
cuneiform cartilages - (2) hyaline
corniculate cartlages - (2) hyaline
epiglottis – (1) elastic cartilage
Larynx
Muscular walls aid in voice production and the swallowing reflex
Glottis – the superior opening of the larynx
Epiglottis – prevents food and drink from entering airway when swallowing
Speech formation
Composed of two components
1. Phonation
2. Vocalization
Phonation is achieved by larynx
Vocalization is achieved by structures in mouth
Phonation
o The larynx actually acts as a vibrator
o And the vibrating element are the VOCAL CORDS
o The stretching and positioning of vocal cords by various muscles is responsible for the
production of voice
During normal quite breathing , the vocal cords are wide open to allow the entry and exit of air
During phonation, the cords move together so that passage of air between them will cause
vibration.
The pitch of the vibration is determined by
1.Degree of stretch of the cords
2.How tightly the cords are approximated to one another
3.Mass of their edges.
Phonation
Movement of vocal cords:
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The vocal cords can be stretched by either forward rotation of the thyroid cartilage or posterior rotation
of the arytenoid cartilages, activated by muscles stretching from the thyroid cartilage and arytenoid
cartilages to cricoid cartilage.
Muscles located within the vocal cords lateral to the vocal ligaments, the thyroarytenoid muscles, can
pull the arytenoid cartilages toward thyroid cartilage thus loosen the vocal cords.
Parts of these muscles within the vocal cords can change the shapes and masses of the vocal cord
edges, sharpening them to emit high-pitched sounds and blunting them for the more bass sounds.
Cough reflex
Structures sensitive to foreign stimilui
1.Trachea
2.Carina ( point where the trachea divides)
3.Bronchi
4.Alveoli
Afferent signals from the respiratory passages goes to medulla via vagus nerve
Then a sequence of events occur as follows:
Steps in production of cough reflex
Step 1: Up to 2.5 liters of air are rapidly inspired
Step 2: The epiglottis closes, and the vocal cords shut tightly to entrap the air within the lungs.
Step 3: The Abdominal muscles contract forcefully, pushing against the diaphragm while other
expiratory muscles, such as the internal intercostals, also contract forcefully. Thus the
pressure in the lungs rises rapidly to about 100 mm Hg or more.
Step 4 : Vocal cords and the epiglottis suddenly open widely, so that air under this high pressure in
the lungs explodes outward.
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Importantly, the strong compression of the lungs collapses the bronchi and trachea by causing their
noncartilaginous parts to invaginate inward, so that the exploding air actually passes through bronchial
and tracheal slits.
The rapidly moving air usually carries with it any foreign matter that is present in the bronchi or trachea.
Sneeze reflex
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Similar to cough reflex, except that it applies to the nasal passageways instead of the lower
respiratory passages.
 The initiating stimulus of the sneeze reflex is irritation in the nasal passageways
 The afferent impulses pass in the fifth cranial nerve to the medulla, where the reflex is triggered.
 A series of reactions similar to those for the cough reflex takes place , however, the uvula is depressed,
so that large amounts of air pass rapidly through the nose, thus helping to clear the nasal passages of
foreign matter.