Skeletal System Flashcards
ontogeny
embryonic development
gastrulation
process that creates the gut of the animal
neurulation
process of forming the neural tube
Organogenesis
formation of organs from tissue
maturation
process from birth/ hatching to adulthood
ectoderm
embryonic tissue layer
mesoderm
embryonic tissue layer
endoderm
embryonic tissue layer
Old hypothesis of ontogeny: ontogeny recapitulates phylogeny,
ontogeny is a condensed version of evolution, all went through fish phase
Alternative hypothesis of ontogeny: Law of the general to the specific
young embryos are undifferentiated, not until later in development that taxon-specific features arise
pharyngeal pouches
bays inside the embryonic pharynx
isometry
growing at same rate
allometry
growing at a different rate
How do vertebrates move?
by changing the angle between joints at the bone
exoskeleton
derived from the dermis or epidermis
endoskeleton
derived from the mesoderm within the body
dermal bone
ossifies directly from fibrous membranes, common in skull, jaws and shoulder girdle
endocranial bone
ossifies from hyaline cartilage, key to long bone formation
chondrocranium
lies in line with the vertebral column, initially formed from cartilage that supports the brain and sensory capsules, three parts: braincase, nasal capsule, and otic capsule
chondrocranium in bony fish is replaced by
endochondral/ cartilage bone
splanchnocraniumm
supports gills and respiratory structures; derives jaws, hyoid, and gill arches;as well as the jaws in gnathostomes composed of a series of arches that originally supported the pharyngeal slits
compenetns of mandibular (arch) jaws
palaroquadrate and Meckel’s cartilage
Palatoquandrate
dorsal component of the mandibular arch
Meckel’s cartilage
ventral component of the mandibular arch
dermatocranium
dermal bones that originally arose as bony armor in early fishes, in gnathostomes sunk and are associated with chondrocranium and splanchnocranium, in modern fish and amphibians the dermal bone is reduced; most bones are encased by bone-derived from the dermatocranium (surrounds everything)
serial theory
jaws arose from a single arch
composite theory
jaws arose from parts of several arches
palatoquadrate reduced to articular element that are called:
quadrate and epipterygoid
palatoquadrate is places by two bones derived from the facial series of the dermatocranium
maxilla and premaxilla
what forms dentry?
dermal bone that surrounds the Meckel’s cartilage
skull fenestration
increase in the ‘openness’ of the skull
cranial kinesis
increase (or decrease) in skull mobility
Sharpey’s fibres
specific collagen fibres that attach the tendon to the bone
ligaments
connects bone to bone
pterygoid walk
mobile bones slide beyond the brain case, detach upper jaw, crawling/ walking jaw along prey, bite down, move other
mammal akinetic skull
mammals lack cranial kinesis, more restricted jaw movement because of distinctive interlocking teeth
vertebral segments
cervical, thoracic, lumbar, sacral, coccygeal
dorsal arches
protect the neural tube, have neural and interneural arches