Forensic medicine medical negligence 2-bolam principle
Anatomy of larynx
1. Dr. THAAER MOHAMMED DAHER ALSAAD
SPECIALIST IN GENERAL SURGERY
M.B.Ch.B.(MBBS) F.I.B.M.S.(Ph.D.)
SENIOR LECTURER
IMS MSU
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5. Movements of the Larynx during Swallowing During swallowing the
elevation of the larynx folds the epiglottis over the glottis, steering
materials into the esophagus
15. LARYNX
• It is the musculocartilaginous structure,
• lined with mucous membrane,
• connected to the superior part of the trachea and to
the pharynx.
• inferior to the tongue and the hyoid bone;
• the essential sphincter guarding the
entrance into the trachea.
• functioning secondarily as the organ of voice.
• It is formed by nine cartilages connected
by ligaments and eight muscles.
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18. The Larynx
Inspired (inhaled) air leaves the pharynx by
passing through a narrow opening, the glottis.
The larynx begins at the level of vertebra C4 or C5
and ends at the level of vertebra C7.
It is essentially a cylinder whose cartilaginous
walls are stabilized by ligaments or skeletal
muscles or both.
19. External view of the larynx: (a) anterior aspect; (b) anterolateral aspect.
20. Cartilages of the Larynx
Three large unpaired cartilages form the body
of the larynx:
the thyroid cartilage,
the cricoid cartilage,
the epiglottis.
The thyroid and cricoid cartilages are hyaline
cartilages;
the epiglottic cartilage is an elastic cartilage
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22. The Thyroid Cartilage
The largest laryngeal cartilage is the thyroid (“shield-shaped”) cartilage.
It forms most of the anterior and lateral walls of the larynx .
The thyroid cartilage, when viewed in sagittal section, is incomplete
posteriorly.
The anterior surface of this cartilage bears a thick ridge, the laryngeal
prominence.
This ridge is easily seen and felt, and the thyroid cartilage is commonly
called the Adam’s apple.
During embryological development, the thyroid cartilage is formed by
two pieces of cartilage that meet in the anterior midline to form the
laryngeal prominence.
The inferior surface of the thyroid cartilage articulates with the
cricoid cartilage;
the superior surface has ligamentous attachments to the epiglottis and
smaller laryngeal cartilages.
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24. The Cricoid Cartilage
The thyroid cartilage sits superior to the cricoid “ring-
shaped”) cartilage.
It is a complete ring whose posterior portion is greatly
expanded, providing support in the absence of the thyroid
cartilage.
The cricoid and thyroid cartilages protect the glottis and
the entrance to the trachea,
and their broad surfaces provide sites for the attachment
of important laryngeal muscles and ligaments.
Ligaments attach the inferior surface of the cricoid
cartilage to the first cartilage of the trachea.
The superior surface of the cricoid cartilage articulates
with the small paired arytenoid cartilages.
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26. The Epiglottis
The shoehorn-shaped epiglottis projects
superior to the glottis
The epiglottic cartilage that supports it has
ligamentous attachments to the anterior and
superior borders of the thyroid cartilage and the
hyoid bone.
During swallowing, the larynx is elevated, and
the epiglottis folds back over the glottis,
preventing the entry of liquids or solid food into
the respiratory passageways.
27. Paired Laryngeal Cartilages
The larynx also contains three pairs of
smaller cartilages:
the arytenoid,
corniculate,
and cuneiform cartilages.
The arytenoids and corniculates are hyaline
cartilages;
the cuneiforms are elastic cartilages.
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29. The Three Paired Cartilages
• The arytenoid "ladle-shaped” cartilages articulate with
the superior border of the enlarged portion of the
cricoid cartilage.
• The corniculate “horn-shaped”) cartilages articulate
with the arytenoid cartilages.
• The corniculate and arytenoid cartilages play a role in
the opening and closing of the glottis and the
production of sound.
• Elongate, curving cuneiform “wedge-shaped”)
cartilages lie within the aryepiglottic fold that extends
between the lateral aspect of each arytenoid cartilage
and the epiglottis.
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35. Laryngeal Ligaments
• A series of intrinsic ligaments binds all nine
cartilages together to form the larynx.
• Extrinsic ligaments attach the thyroid cartilage to
the hyoid bone and the cricoid cartilage to the
trachea.
• The vestibular ligaments and the vocal ligaments
extend between the thyroid cartilage and the
arytenoids.
• The vestibular and vocal ligaments are covered by
folds of laryngeal epithelium that project into the
glottis.
• The vestibular ligaments lie within the superior pair
of folds, known as the vestibular folds.
36. Laryngeal Ligaments (continue)
The vestibular folds, which are relatively inelastic, help
prevent foreign objects from entering the glottis and
provide protection for the more delicate vocal folds.
The vocal folds are highly elastic, because the vocal
ligament is a band of elastic tissue.
The vocal folds are involved with the production of sounds,
and for this reason they are known as the true vocal cords.
Because the vestibular folds play no part in sound
production, they are often called the false vocal cords.
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39. Sound Production
• Air passing through the glottis vibrates the vocal folds and
produces sound waves.
• The pitch of the sound produced depends on the diameter,
length, and tension in the vocal folds.
• The diameter and length are directly related to the size of the
larynx.
• The tension is controlled by the contraction of
voluntary muscles that change the relative positions of the
thyroid and arytenoid cartilages.
• When the distance increases, the vocal folds tense and the
pitch rises; when the distance decreases, the vocal folds relax
and the pitch falls.
• Children have slender, short vocal folds, and their voices
tend to be high-pitched.
40. Sound Production (continue)
• At puberty the larynx of a male enlarges considerably more
than that of a female.
• The true vocal cords of an adult male are thicker and
longer, and they produce lower tones than those of an
adult female.
• The entire larynx is involved in sound production because
its walls vibrate, creating a composite sound.
• Amplification and echoing of the sound occur within the
pharynx, the oral cavity, the nasal cavity, and the paranasal
sinuses.
• The final production of distinct sounds depends on
voluntary movements of the tongue, lips, and cheeks.
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42. The Laryngeal Musculature
• The larynx is associated with two different groups of muscles,
the intrinsic laryngeal muscles.
the extrinsic laryngeal muscles.
The intrinsic laryngeal muscles have two major
functions:
One group regulates tension in the vocal folds,
while a second set opens and closes the glottis.
Those involved with the vocal folds insert upon the thyroid,
arytenoid, and corniculate cartilages.
Opening or closing the glottis involves rotational
movements of the arytenoids that move the vocal folds
apart or together.
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47. Part of oblique arytenoid muscle: an inconstant fascicle of the
oblique arytenoid muscle, originating from the apex of the arytenoid
cartilage and inserting to the lateral margin of the epiglottis.
48. • During swallowing, both extrinsic and intrinsic muscles
cooperate to prevent food or drink from entering
the glottis.
• Before you swallow, the material is crushed and chewed
into a pasty mass known as a bolus.
• Extrinsic muscles then elevate the larynx, bending the
epiglottis over the entrance to the glottis, so that the
bolus can glide across the epiglottis, rather than falling
into the larynx.
• While this movement is under way, intrinsic muscles
close the glottis.
• Should any food particles or liquids touch the surfaces of
the vestibular or vocal folds, the coughing reflex will be
triggered.
• Coughing usually prevents the material from entering the
glottis.
49. Extrinsic Laryngeal muscles
• The extrinsic laryngeal musculature positions
and stabilizes the larynx.
• Three of the four strap muscles of the neck,
the omohyoid, sternohyoid and thyrohyoid,
find attachment to it, only the sternothyroid
failing to gain it.
58. Lymph Drainage (skip)
• The vocal cords themselves act as a complete barrier
separating the two lymphatic areas, but posteriorly
there is free communication between them.
• Above the vocal cords, some lymphatics passing via
small nodes lying on the thyrohyoid membrane.
• Below the vocal cords, drainage partially via
nodes on the front of the larynx and trachea.
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62. External view of the larynx: (a) anterior aspect; (b) anterolateral aspect.
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68. Nerve supply
• The nerve supply of the larynx is of great practical
importance and comprises the superior and recurrent
laryngeal branches of the vagus nerve (X).
• The superior laryngeal nerve passes deep to the
internal and external carotid arteries where it divides;
• its internal branch pierces the thyrohyoid membrane
together with the superior laryngeal vessels to supply
the mucosa of the larynx down to the vocal cords.
• The external branch passes deep to the superior
thyroid artery to supply the cricothyroid muscle.
69. The recurrent laryngeal nerve has a different course on each side.
• The right arises from the vagus as this crosses the
front of the subclavian artery, passes deep to and
behind this vessel, then ascends behind the common
carotid to lie in the Tracheo-oesophageal groove
accompanied by the inferior laryngeal vessels.
• The nerve then passes deep to the inferior constrictor
muscle of the pharynx to enter the larynx behind the
cricothyroid articulation.
70. The recurrent laryngeal nerve has a different course on each side.
• The left nerve arises on the arch of the aorta, winds
below it, deep to the ligamentum arteriosum, and
ascends to the trachea. It then lies in the tracheo-
oesophageal groove and is distributed as on the right
side.
• The recurrent nerves supply all the intrinsic
laryngeal muscles, apart from the cricothyroid,
(supplied by the superior laryngeal nerve), and
the mucosa below the vocal cords.
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74. Giraffes are silent animals, but, they are certainly
not mute. Sounds like the bleating of calves, and
the bellowing of cows, have been heard.
