Fetal Development - 12 Weeks: Difference between revisions

From Embryology
No edit summary
Line 44: Line 44:


Also note the developing tongue musculature and its mandibular attachment site.
Also note the developing tongue musculature and its mandibular attachment site.
{{Template:Glossary}}
{{Template:Footer}}
[[Category:Head]] [[Category:Bone]] [[Category:Cartilage]]


[[Category:Human Fetus]] [[Category:Week 12]]
[[Category:Human Fetus]] [[Category:Week 12]]

Revision as of 08:31, 2 September 2010

Introduction

Images on this current page show head ossification occurring during the early fetal period (12 weeks approx 92 mm CRL in size). The head undergoes two different forms of ossification (endochondral and intramembranous) in separate regions of the skull. Furthermore the two images (lateral and medial) identify regions of cartilage development. Compare this 12 week fetus with the earlier 10 week Fetal and Carnegie stage embryos: size, head proportions, brain, head, skeletal development.

Fetal Links: fetal | Week 10 | Week 12 | second trimester | third trimester | fetal neural | Fetal Blood Sampling | fetal growth restriction | birth | birth weight | preterm birth | Developmental Origins of Health and Disease | macrosomia | BGD Practical | Medicine Lecture | Science Lecture | Lecture Movie | Category:Human Fetus | Category:Fetal
Historic Embryology  
1940 Fetus Physiology
Carnegie Fetal: 95 | 96 | 142 | 145 | 184 | 211 | 217 | 300 | 362 | 448 | 449 | 538 | 590 | 607 | 625 | 662 | 693 | 847 | 858 | 922 | 928 | 948 | 972 | 1318 | 1388 | 1455 | 1591 | 1597b | 1656 | 1686 | 2250a | 2250b | 3990 | 5652 | 6581 | 7218

12 week Head

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).

Lateral View

In this lateral (external) view, note the distribution of new bone in the plates of the cranial vault, temporal bone, orbit, upper jaw (maxilla) and lower jaw (mandible) regions. (More? Notes Skull | Face) Bony regions in the lower jaw (mandible) region also show spaces where tooth formation is occuring. (More? Tooth Development)

Fetal head lateral.jpg

Medial View

In this medial (internal) view, note the distribution of cartilage from the nasal region through the base of the skull to the atlas/axis (with new bone forming). See also the original Meckel's cartilage within the newly forming bony mandible.

Fetal head medial.jpg

Mandible

Selected extract of above images showing 2 views (lateral/external left, medial/internal right) of the mandible region.

Note: Cartilage in the neck where the hyoid bone will eventually form. Meckel's cartilage visible in the medial view within the newly forming bone.

Nose and Mouth

(Image: Virginia Diewert)

Selected 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.

Fetal head section.jpg

Terms

choana - the posterior nasal aperture which is the passageway from the back of one side of the nose to the throat. There are two choanae, one on either side of the nose.

mandible

nasal conchae - the thin scroll-shaped bony elements forming three groove-like air passages/chambers in the nasal cavities.

oropharynx - the oral (within the mouth) part of the pharynx which extends from the uvula to the level of the hyoid bone.

Also note the developing tongue musculature and its mandibular attachment site.

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, March 28) Embryology Fetal Development - 12 Weeks. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Fetal_Development_-_12_Weeks

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