Transcript The Larynx
The larynx
The Larynx
The larynx constitutes the
organ of phonation
and forms a
protective sphincter
respiratory system.
to the It lies in the median part of the front of the neck, opposite the
3 rd , 4 th , 5 th and 6 th
cervical vertebrae.
It extends from the
upper border of epiglottis
to the lower border of
cricoid cartilage
.
Its upper end opens into the laryngopharynx by the
laryngeal inlet
.
Its lower end is
continuous with the trachea
at the level of the sixth cervical vertebra.
The Larynx
The larynx is formed by a cartilaginous skeleton attached together by joints by muscles and ligaments and all are covered by and moved mucous membrane .
Laryngeal cartilages:
A. Single
: 1.
Thyroid cartilage.
2.
Cricoid cartilage.
3.
Epiglottis cartilage.
B. Paired:
1.
Arytenoid cartilages.
2.
Corniculate cartilages.
3.
Cuneiform cartilages.
Thyroid Cartilage
The largest laryngeal cartilage.
Formed of 2 quadrilateral
laminae
which are
fused anteriorly.
Posteriorly
, the 2 laminae are
separated
by a wide gap The
anterior border
forms a median
projection
, the
laryngeal prominence.
The laminae present a median
V-shaped notch
, the
superior thyroid notch.
The
posterior borders
form upward and downward
projections
,
superior and inferior horns.
The
outer surface
of each lamina shows an oblique ridge, the
oblique line.
The oblique line extends between two
tubercles
, the superior and inferior
thyroid tubercles.
Cricoid Cartilage
Smaller, but thicker than the thyroid cartilage.
Lies below and behind the thyroid cartilage.
It has the shape of a
signet ring
with a quadrilateral
lamina
posteriorly and a narrow
arch
anteriorly.
Its lower border is horizontal.
Its upper border is sloping.
Epiglottis Cartilage
A leaf-shaped lamella of elastic cartilage.
It projects upwards behind the tongue and hyoid bone.
Has an upper broad free end and a lower tapering end.
Anteriorly, it is connected to: – The root of the tongue, by the median and lateral glosso epiglottic folds.
– The hyoid bone, by the hyoepiglottic ligament.
– The inner surface of the thyroid cartilage by the thyroepiglottic ligament.
Arytenoid Cartilage
A pyramidal-shaped cartilage, with an apex, base and 3 surfaces: – Posterior surface.
– Anterolateral surface.
– Medial surface.
The apex is directed upwards and articulates with the corniculate cartilage.
The base is directed downwards and articulates with the upper border of the lamina of cricoid cartilage.
The lateral angle of the base projects and forms the
muscular process
.
The anterior angle of the base projects to form the
vocal process
.
Corniculate Cartilage
A small cartilage on the apex of the arytenoid cartilage Enclosed in the aryepiglottic fold forming the
corniculate tubercle
Cuneiform Cartilage
A small nodule enclosed in the aryepiglottic fold forming the
cuneiform tubercle
Joints of the Larynx
Cricothyroid joints:
– One on each side.
– A synovial joint between the inferior horn of the thyroid cartilage and the side of the cricoid cartilage.
Cricoarytenoid joints:
– One on each side.
– A synovial joint between the base of arytenoid cartilage and upper border of the lamina of cricoid cartilage.
Arycorniculate joints:
– One on each side.
– A joint between the apex of the arytenoid cartilage and the corniculate cartilage.
Membranes and ligaments
1.
2.
Thyrohyoid membrane and ligaments.
Fibroelastic membrane.
3.
4.
5.
Quadrangular membrane.
Vestibular ligament.
Cricothyroid ligament (conus elasticus).
6.
7.
8.
Vocal ligament.
Hyoepiglottic ligament.
Thyroepiglottic ligament.
9.
Cricotracheal ligament.
Thyrohyoid membrane
Extends from the
upper border
of thyroid cartilage to the
upper border
of posterior surface of hyoid bone Separated from the posterior surface of hyoid bone by the
hyoid bursa.
The median part of the membrane is thickened to form the
median thyrohyoid ligament.
The posterior border is thickened to form the
lateral thyrohyoid ligament.
The membrane is
pierced
vessels and the by the superior laryngeal internal laryngeal nerve .
The lateral thyrohyoid ligament contains a cartilage nodule called the
cartilago triticea
.
Fibroelastic membrane
Its upper part is called quadrangular membrane and its lower parts is called cricothyroid ligament (conus elasticus).
The quadrangular membrane:
– It extends between the lateral border of the epiglottis and the arytenoid cartilage.
– Its lower free border forms the
vestibular ligament
.
The cricothyroid ligament (conus elasticus):
– An elastic band which lies below and on the inner aspect of the thyroid cartilage.
– It is connected to thyroid cartilage, cricoid cartilage and arytenoid cartilage.
– Two parts of the ligament can be recognized:
1.
2.
Median cricothyroid ligament:
– the
anterior
thickened part of the ligament which connects the adjacent borders of the cricoid and thyroid cartilages.
– The ligament is overlapped by the
cricothyroid muscle
.
Lateral cricothyroid ligament (crico-vocal membrane)
– this ligament is attached inferiorly to the upper border of cricoid cartilage – superiorly, it has 2 attachments: to the inner surface of
thyroid cartilage
, anteriorly.
to the
vocal process
of arytenoid cartilage, posteriorly.
– The free upper border of the crico-vocal membrane is called the
Vocal Ligament
.
– So, the
vocal ligament
is attached to the
inner surface
of thyroid cartilage (anteriorly) and to the
vocal process
of the arytenoid cartilage (posteriorly).
Other ligaments
Hyo-epiglottic ligament
: connects the anterior surface of epiglottis to the hyoid bone
Thyro-epiglottic ligament
: connects the lower end of the epiglottis to the inner surface of thyroid cartilage
Crico-tracheal ligament
: connects the lower border of the cricoid cartilage to the first ring of trachea
Ligaments of the joints .
Laryngeal Inlet
The opening of communication between the pharynx and larynx.
It is directed upwards and backwards
Boundaries:
– Upper border of
epiglottis
anteriorly.
–
Aryepiglottic folds
on both sides.
– Mucous membrane between the arytenoid cartilages posteriorly.
Aryepiglottic fold:
– Is a fold of mucosa extending between the apex of arytenoid cartilage and the side of epiglottis.
– It encloses the
aryepiglottic muscle
,
cuneiform
and
corniculate
cartilages.
Laryngeal Cavity
Vocal fold:
– A fold of mucous membrane extending from the inner surface of
thyroid cartilage
to the
vocal process of arytenoid cartilage.
– The folds enclose the
vocal ligaments
(upper border of lateral cricothyroid ligaments).
– The fissure between the 2 vocal folds is called the
rima glottidis.
Vestibular fold:
– A fold of mucous membrane extending from the inner surface of
thyroid cartilage
to the
anterolateral surface of arytenoid cartilage.
– It encloses a fibrous band called the
vestibular ligament.
Sinus of the larynx:
– A recess between the vestibular and vocal folds
Vestibule of the larynx:
– The part of the cavity between the inlet and the vestibular folds
– –
Muscles of the larynx
Extrinsic muscle: Elevators:
– Digastric, stylohyoid, mylohyoid, geniohyoid, stylopharyngeus, salpingopharyngeus and palatopharyngeus.
Depressors:
Sternothyroid, sternohyoid, omohyoid muscles and the elastic recoil of the trachea.
–
Intrinsic muscles: Acting on the laryngeal inlet: Narrowing:
oblique arytenoid and aryepiglottic muscles.
Widening:
thyroepiglottic muscle.
Acting on the vocal cords: Sphincteric action:
–
Adduction:
lateral cricoarytenoid & transverse arytenoid.
–
Abduction:
posterior cricoarytenoid.
Change in length and tension:
–
Elongation and tension:
cricothyroid.
–
Shortening and relaxation:
thyroarytenoid and vocalis.
Oblique arytenoid Muscle
Origin
: from the back of the muscular process of the arytenoid cartilage.
Insertion
: into the apex of the opposite arytenoid cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: narrowing of the laryngeal inlet by bringing the two aryepiglottic folds together.
Aryepiglottic Muscle
Origin
: from the apex of the arytenoid cartilage as a continuation of the oblique arytenoid muscle.
Insertion
: cartilage.
into the side of the epiglottis
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: narrowing of the laryngeal inlet by shortening the aryepiglottic fold.
Thyroepiglottic Muscle
Origin
: from the inner surface of the thyroid cartilage.
Insertion
: into the side of the epiglottis cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: widening of the laryngeal inlet.
Lateral Cricoarytenoid Muscle
Origin
: from the upper border of the arch of cricoid cartilage.
Insertion
: into the muscular process of the arytenoid cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: Adduction of the vocal cords by rotation of the arytenoid cartilage.
Transverse Arytenoid Muscle
Origin
: from the back and medial surface of the arytenoid cartilage.
Insertion
: into the back and medial surface of the opposite arytenoid cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: Adduction of the vocal cords by approximating the arytenoid cartilages.
Posterior Cricoarytenoid Muscle
Origin
: from the posterior surface of the lamina of the cricoid cartilage.
Insertion
: into the muscular process of the arytenoid cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: Abduction of the vocal cords by rotating the arytenoid cartilage.
Thyroarytenoid Muscle
Origin
: from the inner surface of thyroid cartilage lateral to the cricothyroid ligament.
Insertion
: into the antero-lateral surface of arytenoid cartilage.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve).
Action
: shortening and relaxation of the vocal fold.
Vocalis Muscle
Origin
: deep fibers of thyroarytenoid.
Insertion
: into the vocal process of arytenoid cartilage and vocal ligament.
Nerve supply
: recurrent laryngeal nerve (branch of vagus nerve.
Action
: shortening and relaxation of the vocal fold.
1.
Nerve Supply of the Larynx
Superior laryngeal nerve
(from vagus nerve) divides into:
2.
A. External laryngeal nerve cricothyroid muscle
.
(motor)
: supplies the
B. Internal laryngeal nerve
the
mucous membrane
vocal folds.
(sensory)
: supplies
above
the level of the
Recurrent laryngeal nerve
divides into
motor
and (from vagus nerve)
sensory
branches: – The motor branch supplies
ALL
intrinsic muscles of the larynx (
except cricothyroid muscle
).
– The sensory branch supplies the
mucous membrane below
the level of the vocal folds.
Blood supply of the larynx
Arterial supply of the larynx
: 1.
Superior laryngeal artery (from superior thyroid artery from external carotid artery).
2.
Inferior laryngeal artery (from inferior thyroid artery from thyrocervical trunk from 1 st part of subclavian artery).
Lymph drainage of the larynx
To the deep cervical lymph nodes.
1.
Clinical Points of the Larynx
Injury of the external laryngeal nerve:
Paralysis of the cricothyroid muscle which affects the voice (weakness) with no effect on air pathway.
2.
Injury of the recurrent laryngeal nerve: 1. Unilateral complete section
: the affected vocal cord will be between adduction and abduction (cadaveric position). The other cord will compensate and crosses to the other side and this will not affect the voice or respiration
2.
Clinical Points of the Larynx
Bilateral complete section
: both vocal cords will be between adduction and abduction (cadaveric position). The voice will be lost and the respiration is slightly affected.
3.
Unilateral partial section
: the affected side will show paralysis of the abductor muscle (posterior cricoarytenoid), the affected vocal cord will stay in adduction position, the other cord will compensate.
Clinical Points of the Larynx
4.
Bilateral partial section
: a severe condition because both vocal cords will be paralyzed in adducted position). The patient will suffer from stridor and asphyxia and tracheostomy or cricothyriodotomy is life saving process.