Larynx Of An Infant Different From Adult

The larynx of an infant differs considerably from that of
an adult and has a great clinical significance.
1. Infant's larynx is positioned high in the neck opposite
C3 or C4 (vocal cord level ) at rest and reaches C1 or
C2 during swallowing. This high posit ion allows the
epiglottis to meet soft palate and make a nasopharyngeal
channel for nasal breathing during suckling. The
milk feed passes separately over the dorsum of tongue
and the side of epiglottis, thus allowing breathing and
feeding to go on simultaneously.
2. Laryngeal cartilages are soft and collapse easily.
Epiglottis is omega-shaped and arytenoids relatively
large covering significant portion of the posterior
glottis .
. 3. Thyroid cartilage in an infant is flat. It also overlaps
the cricoid cartilage and is in turn overlapped by
the hyoid bone. Thus cricothyroid and thyrohyoid
spaces are narrow and not easily discernible as landmarks
when performing tracheostomy.
4. Infant's larynx is small and conical. The diameter of
cricoid cartilage is smaller than the size of glottis,
making subglottis the narrowest part. It has a bearing
in the selection of paediatric endotracheal tube.
In adults, subglottic-glottic dimensions are approximately
same and larynx is cylindrical.
5. Submucosal tissues of infant's larynx are comparatively
loose and easily undergo oedematous change
with trauma or inflammation leading to obstruction.
Infant's larynx shows two spurts in growth. In the first
three years of life larynx grows in width and length, and
thus obviates the need for any airway surgery in certain
congenital anomalies. The second spurt in growth occurs
during adolescence when the thyroid angle develops. The
length of vocal cords then increases leading to voice
changes associated with puberty. With
growth of the neck, larynx gradually descends to adult
position opposite Cs (vocal cord level).

In childhood, vocal cord is 6 mm in femal <; and mm
in males. It increases to 15-19 mm in adult fem:1 le and
17-23 in adult male.