BGDB Face and Ear - Fetal
Practical 6: Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities |
Fetal Growth
<Flowplayer height="320" width="285" autoplay="true">fetal growth.flv</Flowplayer> |
In this cartoon movie of fetal growth, observe the changing relative sizes of the head and body.
|
Fetal Head Growth
Head Circumference Growth (both gestational and post-fertilisation ages are shown)
Skull Ossification
These are 2 views of the same 12 week 92 mm CRL human fetus head, double stained to show both cartilage (blue) and newly-formed bone (red). The head undergoes two different forms of ossification (endochondral and intramembranous) in separate regions of the skull.
Mandible Ossification
Face
The cartilage template of the mandible and the base of the skull are replaced by early bone development.
Selected midline medial head view showing key features of head musculoskeletal and neurological development.
Note extensive nasal cartilage, nasal conchae, pituitary, secondary palate, oral cavity, tongue, mandible, hyoid, choana, oropharynx.
Also note the developing tongue musculature and its mandibular attachment site.
Note that the cranial vault, the portion of the skull enclosing the brain, ossifies by a unique bone formation process, intramembranous ossification.
Because the head contains many different structures also review notes on Special Senses (eye, ear, nose), Respiration (pharynx), Integumentary (Teeth), Endocrine (thyroid, parathyroid, pituitary) and Musculoskeletal (tongue, skull).
Palate Development
Embryonic Palate (week 7) | Quicktime | Flash | Quicktime | Flash |
Palate Overview
Embryonic
- week 4 - pharyngeal arch formation, first pharngeal arch contributes mandible and maxilla.
- week 6 - 7 - primary palate formation maxillary processes and frontonasal prominence.
Fetal
- week 9 - secondary palate shelves fuse, separating oral and nasal cavities.
Hearing
- Week 9 - Mesenchyme surrounding membranous labryinth (otic capsule) chondrifies.
- Week 12-16 - Capsule adjacent to membranous labryinth undegoes vacuolization to form a cavity (perilymphatic space) around membranous labrynth and fills with perilymph.
- Week 18 - ectodermal plug in external auditory meatus breaks down.
- Week 16-24 - Centres of ossification appear in remaining cartilage of otic capsule form petrous portion of temporal bone. Continues to ossify to form mastoid process of temporal bone.
- 3rd Trimester - Vibration acoustically of maternal abdominal wall induces startle response in fetus.
Central Pathway
- 26 weeks - human brainstem auditory pathway is anatomically formed.
- 28 weeks - AABR can be recorded.
less than 34 weeks - latencies of AABR components (I, III, and V) decrease as a function of gestation
Practical 6: Trilaminar Embryo | Early Embryo | Late Embryo | Fetal | Postnatal | Abnormalities |
BGDB: Lecture - Gastrointestinal System | Practical - Gastrointestinal System | Lecture - Face and Ear | Practical - Face and Ear | Lecture - Endocrine | Lecture - Sexual Differentiation | Practical - Sexual Differentiation | Tutorial
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 15) Embryology BGDB Face and Ear - Fetal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDB_Face_and_Ear_-_Fetal
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G