the skull Flashcards
chondrocranium, or it with sensory capsules, or ossifies parts of the chondrocranium
Neurocranium
bones from original cartilaginous shelf
chondrocranium (inside of skull)
bones from gill arches
spanchnocranium
-where is is depends on what type of organism you are
dermal bones
dermatocranium (outside of skull)
in this the Chondrocranium arches up laterally and seals off at top
chondrichthyes
in this the Chondrocranium ossifies at least somewhat
most vetrs
in this the Chondrocranium forms a shelf or bowl that supports brain and covers sensory structures (nasal, optic, and otic capsules)
primative
Head mesenchyme condenses next to notochord forming cartilages , including capsules, then cartilages fuse and ossify
Embryology
gives oxygen to eye and brain in splanchnocranium , lost or reduced in fast swimmers
spiricle
becomes ear ossicles, helps breathing rate and is responsible for moving the tongue
hyoid bone
takes over formation of facial bones from mesodermal cells
neural crest contribution
first or second gill arch forms jaws
next formed hyoid
Serial hypothesis
second and third arch formed madibular arch, next hyoid, parts of all incorporated into skull
composite hypothesis
in us, jaws switch from splanchnocranium to _______
dermatocranium
Branchials not associated with cranium
Paelostyly this is in agnathans
Palatoquadrate suspended from Cranium w/out help from hyoid
Euautostyly
placoderms and acanthodians
Jaws suspended from Hyomandibula
Hyostyly
this is in most modern sharks
Palatoquadrate suspended by ligaments at front and back
Amphistyly
early sharks
Jaws suspended from Hyomandibula, which is incorporated into skull (suspensorium) Symplectic
hyostyly
actinopterygii
lowr jaw attaches to cranium by quadrate Hyomandibulla=Stapes and Tetrapods
Metautostylu
lower jaw attaches to cranium by squamosal
Ouadrate=Incus
Articular=malleus
craniostyly
=us
whats forming in dermatocranium
first is ostracoderms
roof of skull
Modern Jaw (draw it out)
Spanchnocranium
- quadrate/incus
- articular/malleus
- angular/tympanic
dermatocranium
- maxilla
- premaxilla
- dentart
chondrocranium
-squamosal
joints in skull other than jaw joint
transverse hingelike joint across skll roof and transverse, sliding basal join in roof of mouth
cranial kinesis
maybe vert but no cranium
Haikouichthys
simple cranium
hagfish
cranium developed fairly well
lampreys
added dermatocranium, forming head shield
ostracoderms
used under stress in squamates and feeding and breathing in fish
buccal force pump
have a kinetic joint
coelacanths
jaws fuse to braincase, supposidly akinetic
lungfish
had naris and labyrinthodont teeth
Osteolepimorphs + Tetrapods
gill arches present in larvae and hyoid apparatus in adults
modern amphibians
in frogs the hyomadibula turns to the ______
stapes
vivrations sent up through jaw into jaw joint and then ear this is in early amnotes
auditory chain
why do we have temporal fenestrae
results in stronger adduction and more space for muscles
reptilian kinesis
-nerocranium remains still
joint at the back of the skull
metakinesis
-primitive in lizards
joint just behind orbit
mesokinesis
joint in fron tof eye
prokinesis
snakes and birds
penulous quadrate
most lizzards birds and snakes
streptostyly
can slide mandible back and forth
-primitive skull and two temporal finestra
tuataras
have secondary palate
crocodilians
ability to flex upper jaw
rhynchokinesis
muscles pull quadrate forward and palate slides along palatine
slider-crank Mechanism
soft palate
completes to trachea
-so you can chw and breath at the same time
when the coronal suture along the back of the skull closes prematurely
coronal syntosis
