NORMAL EARS
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EMBRYOLOGY |
ULTRASOUND |
- Anatomy: Helix, antihelix, scaphoid and triangular fossa, concha tragus, antitragus, intertragic incisure and lobule can be identified sonographically.
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1 = Scapha (scooped out portion between helix and antihelix. 2 =
Helix (rolled up outer frame of the auricle). 3 = Crux 4 = Concha (hollow bowl like portion of outer ear next to
canal 5 =
Tragus (small projection just in
front of ear canal. 6 = Anti-tragus 7 = Inferior
aspect of concha 8 =
Lobe (lobule) – (fleshy lower portion of ear). |
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- Its relative position may be difficult to assess sonographically on 2D imaging, but is well visualized on 3D imaging.
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- Protuberant ears may be mistaken for an encephalocele.
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Ear length (Table) – Lettieri
et.al. 1993
Ear length (Graph) – Lettieri et.al. 1993
- Measured from the edge of the helix to the tip of the lobe.
- It is important to combine both the cartilaginous and lobe portions.
- Length (mm) = 1.1011 × GA (wks) - 9.5089, r2 = 0.962 (1).
- Increases from 6mm at 15 weeks to 33mm at term (1).
REFERENCES |
- Birnholz
JC, Farrell EE. Fetal ear length. Pediatrics 1988;81(4):555-558.