Hi Judy,
You can see how behind I am on posts!

The human infant's larynx *is* high in the throat, partially because of
the relatively short neck, partially perhaps as a protective mechanism
to decrease the risk of aspiration.  The epiglottis and soft palate
actually touch in newborns, and can even interlock in some babies.  This
gives further protection by channeling fluid to the sides of the vocal
folds, so they don't have to integrate closure with the epiglottis
covering them as well as they will later.

Dr. Edmund Crelin thinks that this is a modification that makes crawling
safer (prone positioning with the head elevated), and that this is why
animals that walk on all fours have a higher larynx than those who are
bipedal.  Dr. Crelin was the author of one of the CIBA clinical Symposia
booklets on the structure of the human vocal tract.  Unfortunately, it
is no longer available, but Dr.Crelin does have a self-published book on
the same issue.  The Human Vocal Tract: Anatomy, Function, Development,
and Evolution, by Edmund S. Crelin, Vantage Press, NY,1987.  Dr. Brian
Palmer found him retired in CT, and says that Dr. Crelin would welcome
calls from people who wish to buy a copy of his book from him directly.

Anyway, the larynx being high in the neck has definate implications for
breastfeeding:
1. Infants can tolerate much more head extension than adults and still
swallow comfortably (this allows us to position kids with micrognathia
with significant head extension so they can breastfeed)
2. Infants with low tone, especially preterm infants, are less able to
tolerate head flexion (chin-tuck) because the larynx obstructs the
airway in this position.  Beware of flexing infant heads, especially
when swaddling or feeding.
3. Infants with laryngomalacia will have a far harder time breathing in
the first 6-18 months than they will after their larynx grows downward
with the growth of the neck, because the floppy epiglottis will no
longer fall into the larynx on inspiration.  Again, head extension helps
to reduce airway resistence and helps these little ones breathe during
the stress of feeding.
--
Catherine Watson Genna, IBCLC  New York City  mailto:[log in to unmask]

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