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44 Cards in this Set
- Front
- Back
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Neurocranium |
primary floors and walls of cranium, protects brain and sensory structures, all vertebrate have this (replacement bone) |
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Development of chondrocranium |
-cartiliagionous neural cranium that is in the skull |
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Prechordal cartilage |
traveculae cranii from underneath brain and anterior to the notochord -form under forebrain region -form nasal capsules in orbits -form rostrum -expands to become ethmoid plate |
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Parachordal cartilage |
form beside and behind notochord -forms floor of hindbrain -expands to form the basal plate -1-2 occipital condyles and foramen magnum |
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sense capsules |
a floor of cranium forms so do sensory capsules -olfactory capsules -otic capsule for inner ear structures -optic capsule (outer covering of eye, not attached) |
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Ethmoid plate and basal plate expansion |
ethmoid plate unites with olfactory capsules basal plate unites with otic capsul -foramina remain for blood vessels and nerves -hypophyseal fenestra (in basal plate) remains for pituitary gland |
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Ossification centers |
ethmoid plate, basal plate and sensory capsules ossify to make four ossification centers |
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Ossification center - occipital (back)
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1. Foramen Magnum 2. Basioccipital 3. Exoccipital 4. Supraoccipital 5. Occipital Condyles |
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Ossification center -Otic Center (ears) |
housing of the important ear structures that turn to bone |
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Ossification center -Sphenoid (floor of cranial cavity)
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-Basisphenoid -presphenoid/Sphenethmoid
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Ossification Center - Ethmoid
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1. Ethmoid plate 2. Olfactory capsules 3. turbinates inmammals |
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Dermatocranium |
membrane bone (dermal bone) which evolved from dermal armor |
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Roofing bones
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a. Nasal
b. Frontal
c. Parietal
d. Orbit 1. Lacrimal – means tears 2. Jugal =Infraorbital = Zygomatic
e. Squamosal |
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Upper and Lower Jaw |
a. Premaxilla - upper b. Maxilla - upper c. Dentary – lower,largest d. Splenial – lower,small, dorsomedial e. Surangular –lower, lateral f. Angular – lower,medial, becomes tympanic bulla g. Coronoid – lower,medial h. Prearticular –lower, medial and caudal – becomes anterior malleus in mammals |
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Primary palatal bones |
roof of oral and gill regions - roof of oropharygngeal cavity in fish and amphibians, roof of nasal cavity in amniotes -Vomer -Palatine -Pterygoid |
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Opercular bones |
Dermatocranium |
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Splanchnocranium - visceral skeleton |
supports and allows movement of jaws, gills, tongue, associated with hearing. Evolution is ancient. Replacement bone. Typically 6 gill slits supported by visceral arches |
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Visceral arch |
gill in function and has five segments a. Pharyngobranchial b. Epibranchial c. Ceratobranchial d. Hypobranchial e. +/- Basibranchial |
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Mandibular arch |
Visceral Arch 1 a. Palatoquadrate b. Mandibular =Meckel’s Cartilage |
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Hyoid arch
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Visceral Arch II a. Hyomandibula
b. Ceratohyal
c. Basihyal
E.Interrelationships – the neurocranium, dermatocranium and splanchnocranium eventually becomes intimately associated to form one single firm skull |
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Agnatha |
Chondrocranium protect brain otic and nasal organs, visceral skeleton continuous and branchial in function, Dermal skeleton depending on group |
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Placoderms |
cartiliaginous chondrocranium, jaws form first visceral arch in splanchnocranium with autostylic suspension, dermal armor |
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Chondrichtheyes |
-Chondrocranium is calcified, has 2 occipital condyles and foramen magnum, otic and nasal capsule are fused to the neurocranium -no dermal bones -Splanchnocranium is mandibular arch and hyoid arch |
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Condrichthyes jaw suspension |
*amphistylic - a lot of movement, primitive sharks *hyostylic - a little movement, most sharks, hyomandibula hangs from otic capsules *autostylic - chimeras, no movement |
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Bony Fish Neurocranim
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incomplete above brain -Chondrostean - cartilaginous in most Holosteans - cartilaginous Teleosts have a large # of bones, ossification centers of walls/floor are ethmoid, sphenoid, otic and one occipital condyle -Dipnoans - cartilaginous
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Bony Fish Dermatocranium |
complete joins to pectoral girdle, supports teeth (maxilla, premaxilla), moveable bony operculum |
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Bony Fish Splanchnocranium |
Bone replacement except in dipnoans -quadrate replaces palatoquadrate -articular -Hyomandibular Arch II is not branchial in function -jaw suspension: Hyostylic in ray finned fish, amphistylic in crossopterygians, autostylic in Dipnoans |
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Amphibian Neurocranium and Dermatocranium |
Neurocranium is incomplete dorsally with more cartilage than bony fish, not joined to the pectoral girdle, 2 occipital condyles |
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Amphibian Splanchnocranium |
larval stages have fish like gills -quadrate upper jaw is autostylic -epipterygoid absent -articular is lower jaw, Meckel's cartilage is homologous to articular bone -Columella (stapes) - hyomandibula is not needed since autostylic suspension -Hyoid apparatus - Arches II, III and IV are not needed and become hyoid apparatus -Larynx - Arch V becomes the larynx -Arch VI, VII are absent |
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Reptile Neurocranium |
decreased # of bones, 1 occipital condyle and well ossified |
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Reptile Dermatocranium |
full complement with some reduction in roof bones |
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Reptile Dermatocranium temporal region |
* |
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Temporal fossa or fenestra |
infratemporal arch is below the ventral fossa zygomatic arch = infratemporal arch in upper classes Supratemporal arch is below the dorsal fossa |
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Anapsid |
Turtle, stem reptiles -no arch on the side of the skull |
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Synapsid |
mammal like reptile -infratemporal arch only -ventral fossa only |
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Diapsids |
Lizards and crocs have modifications -infratemporal and supratemporal arches present |
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Euryapsids |
Extinct reptiles such as Pleisosaurs and Ichthyosaurs with one dorsal fossa -only dorsal fossa and supratemporal arch |
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Rotary chewing |
fossas and arches provide room for huge chewing muscles to allow for rotary chewing |
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secondary palate |
separation between nasal and oral passages allows for breathing and chewing at the same time -Palatine process of maxilla -palatine bones shift down and become part of secondary palate -internal nares shift posteriorly this allows for chewing and breathing at the same time |
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Reptile Splanchnocranium |
similar to amphibians -quadrate (autostylic suspension) -articular -stapes (functional columella) -Hyoid apparatus where tongue can move -Larynx is Arch V |
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Changes in Therapsids (premammals) |
Neurocranium is more like a mammals with 2 occipital condyles -Dermatocraium has synapsid fossa arrangement like mammals -Splanchnocranium frees up the quadrate and articular bones includes squamosal and dentary articulate |
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Bird Neurocranium |
highly vaulted modified reptile skull, incomplete dorsally, well ossified and fused with 1 occipital condyle |
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Bird Dermatocranium |
Supratemporal arch is lost with one big opening confluent with orbit, premaxilla and dentary are apart of the beak, cranial kinesis with pivoting quadrates |
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Bird Splanchnocranium |
similar to reptiles |
