Cranial Cavity--Sievert Flashcards
(133 cards)
What are the 2 main divisions of the skull?
- Neurocranium–the area that surrounds the brain
2. Viscerocranium–bones of the face
How is the neurocranium mainly formed? Which bones are components?
mainly large flat bones
formed mainly intramembranously
What are the 3 embryological derivatives of the skull?
Neural crest–Ectoderm
Paraxial Mesoderm–Somites
Lateral Plate Mesoderm
Where does the division b/w the neural crest & the somites occur?
this happens at the precordal plate at the rostral end of the notochord.
T/F Sometimes there is overlap that occurs in which some paraxial mesoderm is anterior to the prechordal plate.
False. If you are anterior to the prechordal plate–>neural crest cells.
What is the embryological derivative of the sphenoid bone?
most of it is neural crest
a small posterior portion of it is paraxial mesoderm
There is a chunk of neural crest tissue @ the rostral end of the notocord. What does it give rise to? What is the clinical significance of this?
Facial Structures of the skull
Heart Structures
**if you see congenital facial deformities in a child, look for heart problems–>probably present b/c they originate from the same tissue.
Which embryonic derivative does the laryngeal cartilage come from?
lateral plate mesoderm.
What are the 2 types of bone formation?
Endochondral Ossification
Intramembranous Ossification
What are the 2 components of the neurocranium?
The membranous & cartilaginous parts.
What makes up the membranous part? Why is it called this?
The frontal bone, parietal bones, part of the temporal bones, part of the occipital bone.
Called this b/c they are formed via intramembranous ossification.
Note: these are mainly flat bones.
The occipital bone is formed via intramembranous ossification & some __________.
endochondral ossification.
The Cartilaginous portion of the neurocranium is called what? It is formed via which type of ossification? This mainly applies to bones in the _______.
Called chondrocranium
Formed via endochondral ossification.
Mainly in bones in the base of the skull.
Which bones are a part of the chondrocranium–cartilaginous portion of the neurocranium?
Sphenoid Bone
Ethmoid Bone
Part of Temporal Bone
Part of Occipital Bone
T/F All of the components of the neurocranium are from the embryological derivative paraxial mesoderm.
FALSE. They come from different embryological derivatives…these are separate concepts. Think about fcn of housing brain when you think about the neurocranium.
So the sphenoid bone is derived from both neural crest & paraxial mesoderm & is a part of the cartilaginous portion of the neurocranium.
What are the exceptions to the general statement that the large flat bones of the neurocranium are membranous?
The temporal bone & occipital bone are partially formed via endochondral ossification.
T/F Due to their different ossification processes, the temporal bone & occipital bones are a part of both the neurocranium & viscerocranium.
False. They are entirely a part of the neurocranium. They are just partially a part of the membranus & cartilaginous portions of the neurocranium. Once again–>concepts of ossification, neuro v. viscerocranium, & embryological derivatives. A LOT of overlap.
T/F Bones of the floor of the cranial cavity form via endochondral ossification.
True. This includes the sphenoid, ethmoid, & part of the temporal bone.
Viscerocranium develops primarily from _____ and comes from ______.
-Some parts of the viscerocranium develop from ___________.
membrane
comes from neural crest
**cartilaginous models.
Which parts of the viscerocranium develop from a cartilage model?
middle ear ossicles, laryngeal cartilages and hyoid bone.
When you see craniofacial defects what should you think?
think neural crest problem
look for other defects, including @ the heart.
Why do newborns have a small face?
lack of teeth–>small jaw
no paranasal sinuses
facial bones underdeveloped
Which fontanels do you see in a newborn?
6 Anterior Posterior Sphenoid-Lateral (2) Mastoid-Lateral (2)
What happens @ fontanels in a newborn?
these are areas where flat bones of the skull meet & eventually form sutures
these allow for overlap during the birthing process