ANAT2341 Lab 10 - Postnatal

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ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

Postnatal Hearing

First, look through the adult ear structures and identify their developmental origins.

Adult hearing embryonic origins.jpg

Eustacian tube angle.jpg

Auditory Tube (Eustachian, otopharyngeal or pharyngotympanic tube)

Connects middle ear cavity to nasopharynx portion of pharynx. Tube is normally closed and opened by muscles.

  1. Ventilation - pressure equalization in the middle ear
  2. Clearance - allow fluid drainage from the middle ear

Newborn to adult auditory tube


  • shorter (17-18 mm), narrower and runs almost horizontal
  • Tube is opened by a single muscle, tensor palati muscle


  • longer (twice as long), wider and runs at approximately 45 degrees to the horizontal.
  • Tube is opened by two separate muscles, tensor palati and levator palati

Hearing Testing

Newborn hearing test

Abnormalities in neonatal hearing can impact upon development of the nervous system and developmental learning milestones, early detection is therefore key.

The incidence of significant permanent hearing loss is approximately 1-3/1000 newborns. Neonatal hearing screening is carried out in several countries including the USA, UK and in Australia. In NSW the Statewide Infant Screening Hearing Program (SWISH) was introduced in 2002.

There is also a general guide giving a timetable for a number of simple responses that a neonate should make if hearing has developed normally (More? Neonatal Hearing Check List).

The two major forms of hearing loss are conductive and sensorineural.

State Wide Infant Screening Hearing Program (SWISH) a newborn hearing testing program using an automated auditory response technology (AABR). Program was introduced in NSW Australia in 2002 across 17 area health service coordinators. It is thought that in NSW 86,000 births/year = 86-172 babies potentially born with significant permanent hearing loss.

Automated Auditory Brainstem Response (AABR) uses a stimulus which is delivered through earphones and detected by scalp electrodes. The test takes between 8 to 20 minutes and has a sensitivity 96-99%.

Postnatal Neural

The details of postnatal neural development are beyond the scope of the current course, and also covered in other Anatomy subjects.

Those interested should look at Neural System - Postnatal.


ANAT2341 Lab 10: Introduction | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities | Online Assessment

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Cite this page: Hill, M.A. (2024, June 22) Embryology ANAT2341 Lab 10 - Postnatal. Retrieved from

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G