ANATOMY OF LARYNX

1. Larynx
• Respiratory organ between pharynx and
trachea.
• Acts as a protective sphincter for the air
passage.

3. Skeleton
• Consists; cartilages, ligaments and
membranes.
Cartilages: ( single)
i) Thyroid
ii) Cricoid
iii) Epiglotic

4. Cont…
Cartilages: (paired)
iv) Arytenoid
v) Corniculate
vi) cuneiform
Ligaments: (extrinsic)
i) Cricotracheal
ii) Hyoepiglottic
iii) thyroepiglottic

7. Cont…
Ligaments: (intrinsic)
i) Cricothyroid ligament
Membranes:
i) Thyrohyoid ( extrinsic)
ii) quadrangular ( intrinsic)

9. Composition of cartilages
• Thyroid, cricoid and arytenoid are
composed of hyaline cartilage. Some parts
calcify and ossify with age.
• Epiglottic, corniculate and cuneiform are
composed of elastic fibrocartilage.

12. Joints
• Cricothyroid joint: between inferior horn of
thyroid cartilage and facet on side of cricoid
cartilage. The recurrent laryngeal nerve lies
posterior to this joint. It is a synovial joint.
• Cricoarytenoid joint: between cricoid cartilage
and arytenoid. Allows rotatory and lateral gliding
movements. The gliding movement opens the
vocal folds hence opening the gap between
them ( rima of the glottis)

13. Ligaments and membranes.
• Thyrohyoid membrane: connects whole
length of the upper border of the thyroid
cartilage and superior horns to the body
and greater horns of the hyoid bone.
• Forms border of piriform recess and is
perforated by the internal laryngeal nerve
and laryngeal vessels.

15. Cont…
• Cricotracheal membrane: connects the lower
border of the cricoid cartilage to the first
cartilaginous ring of the trachea.
• Qudrangular membrane: extends between
arytenoid cartilage and epiglottis. Its lower
border is free and consists the vestibular
ligament ( false vocal cord). A mucus membrane
covers its upper border to form the aryepiglttic
folds which form the margins of the inlet of the
larynx.

16. Cont…
• Hyoepiglottic ligament: attaches the
epiglottis to the hyoid bone.
• Thyroepiglottic ligament: attaches the
thyroid cartilage to the epiglottis.

17. Inlet of the larynx
Boundaries:
Front: upper margin of epiglottis.
Lateral: aryepiglottic fold of mucous
membrane.
Posteriorly: mucous membrane between the
arytenoid cartilages.

18. Cavity of the larynx
• Between inlet and lower border of the
cricoid cartilage.
Parts:
i) Upper part ( vestibule)
ii) Middle part.
iii) Lower part.

19. Cont..
Vestibule:
From inlet to vestibular folds. Vestibulor
folds are made of mucous membrame
covering the vestibular ligament.
Walls of vestibule:
Anterior; posterior surface of epiglottis.
Posterior; arytenoid cartilage and
interarytenoid fold of mucous membrane
covering the transverse arytenoid muscle.

20. Cont…
• Lateral; aryepiglottic folds containing the
aryepiglottic muscle.
Rima vestibuli: gap betweem vestibular folds.
Middle part:
From level of vestibular folds to level of vocal folds.
Vocal folds contain vocal ligaments. Vocal
ligaments stretch between thyroid cartilage
infront and arytenoid cartilage behind.

21. Cont…
• Rima glottidis; gap between vocal folds infront
and vocal process of arytenoid cartilage behind.
• Sinus of larynx; small recess between vestibular
and vocal folds.
Lower part: from level of vocal folds to lower
border of cricoid cartilage. Walls formed by the
inner surface of the cricothyroid ligament and
cricoid cartilage.

25. Muscles
• Extrinsic muscles:
i) elevators; move the larynx up during
swallowing.
ii) Depressors; move the larynx down
during the same movement.

26. Cont…
Elevators:
i) Digastric
ii) Stylohyoid
iii) Mylohyoid
iv) Geniohyoid.
All attached to the hyoid bone.
Stlopharyngues, salpingopharyngues, and
palatopharyngues also elevate.

27. Cont…
Depressors:
Sternothyroid, sternohyoid and omohyoid
muscles.

28. Intrinsic muscles.
Muscles controlling laryngeal inlet;
i) Oblique arytenoid;
Origin: muscular process of arytenoid
cartilage.
Insertion: apex of opposite arytenoid
cartilage.
Action: sphincters of inlet. Cotraction closes
and relaxation opens.
Nerve supply: recurrent laryngeal nerve.

29. Cont…
• Muscles controlling movement of vocal folds;
i) cricothyroid:
Origin: side of cricoid cartilage.
Insertion: lower border of thyroid cartilage.
Nerve: external laryngeal nerve.
Action: tense and elongate to increase distance
Btn. Angle of thyroid cartilage and vocal process of
arytenoid cartilages.

30. Cont…
• Thyroarytenoid: ( relaxor)
Origin: inner surface of angle of thyriod
cartilage.
Insertion: anteroleteral surface arytenoid
cartilage.
Nerve: recurrent laryngeal nerve.
Action: shortens and relaxes vocal
ligaments.

31. Cont…
• Lateral cricoarytenoid:
Origin: upper border of arch of cricoid
cartilage.
Insertion: muscular process of arytenoid
cartilage.
Action: moves vocal process medially hence
adducting vocal folds.

32. Cont…
• Transverse arytenoid:
Origin: back and medial surface of arytenoid
cartilage.
Insertion: back and medial surface of
opposite arytenoid cartilage.
Action: closes posterior part of rima glottidis.
Nerve: recurrent laryngeal nerve.

33. Cont…
• Posterior cricoarytenoid:
Origin: back of cricoid cartilage.
Insertion: muscular process of arytenoid
cartilage.
Action: abducts vocal folds.
Nerve: recurrent laryngeal nerve.

35. Nerve supply of the larynx
• Internal laryngeal branch of the superior
laryngeal branch of the vagus nerve gives
sensory supply to the mucous membrane
of the inner lining of the larynx above the
vocal folds.
• Recuurent laryngeal nerve supplies the
mucous membrane below the level of the
vocal folds.

36. Cont..
• Recurrent laryngeal nerve gives motor
supply to the intrinsic muscles , except for
the cricothyroid muscle which is supplied
by the external laryngeal branch of the
superior laryngeal branch of the vagus
nerve.

37. Blood supply
• Superior laryngeal branch of superior
thyroid artery supplies the area above the
vocal folds. Superior laryngeal veins
accompany it and drain into the superior
thyroid veins.
• Inferior laryngeal branch of inferior thyroid
artery supplies the area of the lower half of
the larynx. Veins follow arteries.

38. Lymph drainage
• Upper half: lymphatics accompany
superior thyroid artery and drain into the
upper group of deep cervical nodes.
• Lower half: lymphatics follow the inferior
thyroid artery and drain into the lower
group of deep cervical nodes.
All the above lymphatics then drain into the
prelaryngeal and to the pretracheal nodes.

39. Clinical correlates:
• Compromised airway:
Cricothyroidectomy: insertion of a tube
between the gricoid cartilage and thyroid
cartilage.
Vertical incision made passing through; skin,
superficial fascia ( be ware of the 2
anterior jugular veins in the
midline),investing layer of deep cervical
fascia, pretracheal fascia, larynx.

40. Complications:
• Perforation of upper esophagus
posteriorly. Hence incision should not be
deep.
• Hemorrhage:small branches of the
superior thyroid artery usually cross the
front of the cricothyroid membrane to
anastomose with one another. They
should be avoided.

41. Tracheostomy:
• Thyroid and cricoid cartilages identified
and neck is extended.
• Vertical incision made in cricithyroid
membrane to suprasternal notch.
• Incision goes thru. Superficial fascia and
platysma avoiding the anterior jugular
veins.
• Incise investing layer of deep cervical
fascia.

42. Tracheostomy cont…
• Pretracheal fascia incised.
• Palpate the tracheal rings.
• Identify the isthmus of the thyroid.
• Enter the trachea preferably through the second
ring in the midline.
Complications: hemorrhage, nerve paralysis
(recurrent laryngeal nerve between trachea and
esophagus), pneumothorax( cervical dome of
pleura), esophageal perforation.