The Skull and Visceral Skeleton

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)