the skull and visceral skeleton
DESCRIPTION
What is a skull? Morphologists may refer to… ________________ ________________ ________________ We will consider the “skull” as the “skull” minus the jaws, which are derived from the splanchnocranium. The Skull and Visceral Skeleton. - PowerPoint PPT PresentationTRANSCRIPT
The Skull and Visceral SkeletonWhat is a skull?
Morphologists may refer to…
________________
________________
________________
We will consider the “skull” as the “skull” minus the jaws, which are derived from the splanchnocranium
The Skull and Visceral SkeletonNeurocranium (aka enodcranium, chondrocranium, primary braincase):
*
*
The Skull and Visceral SkeletonNeurocranium origins:
Mesenchyme from …
Cartilages… *
*
“nose” “ears” and “eyes”
Taxonomic variation of neurocrania:
___________… remain loosely associated, fibrous cover dorsally
________________… highly developed, envelopes brain, NO bone
____________… remains in primitive fish below dermatocranium, BUT teleosts and tetrapods exhibit endochondral ossification
The Skull and Visceral Skeleton
The Skull and Visceral SkeletonNeurocranial ossification centers:
___________, ____________, __________ and _____
*Occipital 1-4 bones and one (reptiles, birds and early amphibians) or two (modern amphibians and mammals) occipital _____________
What do these articulate with?
The Skull and Visceral SkeletonNeurocranial ossification centers:
*Sphenoid in humans is composite of __________ and ______________.
Remains as separate bones in some species…
________________ part of this bone
The Skull and Visceral Skeleton
http://www.theodora.com/anatomy/images/image153.gif
Neurocranial ossification centers:
*___________ has greatest tendencies to remain cartilage in tetrapods.
Comprised of ______________and _______________
In humans… *
*
The Skull and Visceral SkeletonNeurocranial ossification centers:
*___________ surrounding the membranous labyrinth can fuse with occipitals or squamous (as in humans) to form the temporal bone
http://embryology.med.unsw.edu.au/wwwhuman/Hum12wk/Hum12wk.htm#12weekHead
______________Derived from dermal bone… however, modern tetrapods exhibit mesenchyme migration and subdermal development
4 basic structures…
The Skull and Visceral Skeleton
1) 2) 3) and 4)
The Skull and Visceral SkeletonDermatocranium:
______________ (cartilaginous fishes) is replaced by _________ and __________ that fuses with other dermatocranial elements
___________(s), _____________ and pterygoids part of primary palate
The Skull and Visceral SkeletonDermatocranium:
_____________… bones that cover and protect the delicate gill structures of bony fish
Amphibian skulls:
Considerably modified from labyrinthodonts, but still ___________
Only ___________ have fully ossified skull… Why?
___________ ossified
Otic capsule exposed dorsally and laterally and in anurans large spaces exist inferiorly too
The Skull and Visceral Skeleton
Non-avian reptile skulls:
Stem reptiles similar to …
Modern reptiles still have some ancestral characteristics, namely well ossified neurocranium and…
______________ (sphenodon and many saurians) Why?
The Skull and Visceral Skeleton
“Apsidity”:
Stem reptiles lacked temporal fossae (_________________)
Ancestors to mammals have a single fossae (__________ skulls)
Modern reptiles have two fossae (_____________ skull)
Extinct dinosaurs have single superior fossae (_________ skull) that may be convergent evolution
The Skull and Visceral Skeleton
_______________:
Development of secondary palate makes …
The Skull and Visceral Skeleton
Cranial kinesis:
Movement of various functional parts of the skull independent of other parts is _________________
Teleost, squamates and birds well adept at this… for example fish can move…
The Skull and Visceral Skeleton
Why?
Birds:
Modified reptile skull in 2 functional regions…1) 2)
Light weight dermal bones and bigger space for large brain
The Skull and Visceral Skeleton
Mammals:
Key features are ____________ (mandible), __________ ________ _________ and ____________
The Skull and Visceral Skeleton
The Skull and Visceral Skeleton
Visceral skull:Derived from …
Origins are _______________
__________________ behind the palatoquadrate (jaw) is homologous to the __________ in mammals.
The Skull and Visceral Skeleton
The Skull and Visceral Skeleton
_______________becomes one of the 3 ossicles in mammals…
The Skull and Visceral Skeleton
_______________becomes one of the 3 ossicles in mammals…
The __________ (or stapes) is present in basal groups.
The Skull and Visceral Skeleton
Other pharyngeal arches become portions of:1) 2) 3) 4)