Exercise 12: The Fetal Skeleton
Are the same skull bones seen in the adult also found in the fetal skull?
No, some areas still remain to be converted to bone.
How does the size of the fetal face compare to its cranium?
Face is smaller
How does this compare to the adult skull?
Adult skull is 1/8th total body length whereas the fetal skull is 1/4th total body length
What are the outward conical projections on some of the fetal cranial bones?
These are ossification centers
What is a fontanel?
Fibrous membranes between the bones of a fetal skull
What is its fate? (fontanel)
becomes bone by 22 months
What is the function of the fontanels in the fetal skull?
Allows skull to be compressed during birth and allows for brain growth during late fetal life.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
vertebrae
Fetus=33 Adult=24
The 5 sacral and 4 coccyx bones of the fetus fuse together - that's why adults only have 24
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
coxal bones
In the adult skeleton the coxal bones have fused (ischium, pubic, and ilium), while in the fetal skeleton these bones have not fused.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
carpals and tarsals
The carpals and tarsals are not ossified in the fetus.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
sternum
Its component parts are not fused in the fetus.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
frontal bone
The frontal bone is split at the midsaggital line at the metopic suture. In adults, the suture closes, creating a solid bone.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
patella
May be absent in the fetus; if present it is unossified.
Quite a bit softer and smaller in the fetus. The kneecap develops throughout childhood and into mid-teens.
Describe how the fetal skeleton compares with the adult skeleton in the following areas:
thoracic cage
In a fetus the rib cage is compressed laterally froming a pointed anterior rib cage surface.
The thorax becomes more rigid with age, costal cartilages ossify
How does the size of the fetus's head compare to the size of its body?
it is much larger leaving the body look too small; than if you compare an adult head to its body it seems to have better proportion.
Fetal Skeleton (Image)