Exam 3 Compiled Flashcards
Compare the general features of the three components of the skull including where they derive from developmentally. How does bone formation in the dermatocranium differ from bone formation in the chondrocranium/neurocranium and splanchnocranium?
splagnocranium- any part of the skull that arises from visceral arches (gill arches), first arose to support pharyngeal slits in filter feeding protochordates, then inbreathing, arises form neural crest cells. cartilage, or ossifies into endocondrial bone. elements contribute to jaw, hyoid, and/or ear formation in various gnathostomes.
chondrocranium or neurocranium overlies and supports brain, cartilage or ossifies into endochondral bone, forms form mesenchyme, supports sensory organs,
dermatocranium- outermost casing of brain by dermal bones providing overall protection, intramembranous ossification arose from bone armor of integument and sank inward to associate with chondrocranium and encase splanchnocranium first found in ostracoderms and placoderms. arose originally from bony armor in sank inward and became closely associated with chondrocranium.
How did the splachnocranium evolve from the pharynx of early chordates? How did it become parts of the middle ear?
We had 7 gill arches in agnathes, with 1st branchial arch of agnathes gives rise to palatoquadrate and meckel’s carilage. While the second arch gives rise to hyomandibula becoming the stapes, styloid ligament, alisphenoid, malleus and incus in several vertebrates.
backbones of gill arches become specializations used for trachea and articulating start of vertebrae starting to move bones out of jaw and have formation of hyoid apparatus developed in mammals.
with the hyoid or hyomandibula (coopted as jaw fulcrum in some taxa).
What are the three main bones that are part of the chondrocranium/neurocranium in humans? How did these three bones evolve? (simple explana:on).
Occipital, ethmoid, and sphenoid
forms form mesenchyme next to notochord, supports sensory organs, in most vertebrate is primary embryonic scaffold, and there is a role for vertebrae for occipital formation in cranium. occipital arch (back of head connecting to vertebra exooccipital, basoocoippital and supra occipital)
ethmoid plate (turbinates)
sphenoid
Which are the three composite bones of the human skull?
occipital derived from mostly chondrocranium and some dermatocranium
temporal from the chondrocranium, dermatocranium and splanchnocranium (ear bones and styloid)
sphenoid found right behind zygomatic arch in fenestra made from sphenoid is chondrocranium, and dermatocranium found behind eye
Compare the mandibular a`achment found in bony fish, sharks, crocodiles and mammals?
sharks hyomandibula attaches lower jaw to rest of jaw
bony fish- have lateral movements of upper jaw and these bones rotate with multiple points of rotation, and rapid change of jaw size and configuration
crocodiles and mammals have has no movement between upper jaw and braincase, they use specialized teeth. mammals- the en:re upper jaw is incorporated into the braincase. The lower jaw is made entirely of the dentary bone, which is also a dermal bone
crocodile- alligators, jaws attaches to braincase through quadrate attached to lower jaw in back by articular bone. stapes- retile have stapes, with the stapes the only ear ossicle in the alligator as in all non-mammalian vertebreates it is long and thing and attaches to small disc-shaped tympaum on prootic depe within external acoustic meatus
What is the difference between a kine:c and akine:c skull? What are three examples of each?
many skulls are kinetic skulls (ancient fish, teleosts, squamates, birds, and early therapsids) having lateral movements of upper jaw and these bones rotate with multiple points of rotation, and rapid change of jaw size and configuration.
akinetic- modern amphibians, turtles, crocodiles, and mammals)- has no movement between upper jaw and braincase, suckling and chewing using specialized teeth
For lab/lecture combo, you should be able to compare, contrast, and learn the major alligator and human skull bones. You should be able to find the corresponding bones and fenestra between specimens.
bones come from mesoderm and neural crest cells
What is the role of the fenestra in synapsid skulls?
fenestra may allow for attachmet of strong jaw muscles and fenestra made by process of contact of two bones sygmatic and temperoral to form process and by having kidn of opening can actually have strong muscular attachment making jaw function (temporalis muscle) attaching all the way up to sagittal crest at top of head very distinguishable male trait of sexual dimoprhism the larger the crest the more powerful the jaw. temporalis muscle attach at superior suture of temporal bone and fenestra alowing for expanded jaw muscle attachment.
How is sound changed from a mechanical pulse into informaHon in the brain in repHles and mammals? When relevant, Talk about the
ear canal, middle ear, and inner ear.
tetrapod hearing: with terrestriality, new mechanisms were needed to bring sound energy from air to inner ear: fluid resists being set into motion by air (.1% transfer) sound enters the ear canal, which is only present in some tetrapods mostly mammals have it, it then enter the middle ear where the sound is gathered and concentrated airborne vibrations from tympanum toward fluid-filled inner ear.
reptiles: one bone with sound and stapes touching tympanum sending vibrations to little ear.
mammals: sound hits tympanum vibration transferring sound through little bones into inner ear. pinna is a therian innovation- ear connecting sound to one area sound gathering devices. with a transition to a three ear bone functional conflict between chewing and hearing. the inner ear is full of fluid lined with hair cells, similar to those of lateral line that responds to movement of fluid when fibers are excited making particular region of calculating vibration like strings on guitar throughout cochlear
malleus in contact with eardrum communicating sound to incus and sound to stapes amplifying the sound (allowing us to wider range of frequency hear more sounds) hitting inner ear and that is transmitting informaiton in direct contact with inner ear.
before: sound passes via articular-quadrates stapes to inner ear. after: with chewing, stronger jaws conflicted with hearing role and jaw transferred to dentary/squamosal while articular/quadrate specialize.
Can you classify teeth according to their variability in the jaw, the number of cusps, and how many replacement sets of teeth a vertebrate can get?
eeth classifications homodont vs. heterodont, polyphyodont vs. diphyodont, thecodont vs. acrodont vs. pleurodont.
homodont- unicuspid snake (each tooth one cusp) same kind of teeth throughout jaws. tricuspid (multiple cusps). heterodont- different types of teeth.
polyphyodont- many sets of sharks. vs. diphyodont with 2 sets (milk teeth deciduous, and permanent teeth) special with rodents and lagomorphs teeth continuously grow resharpening when eating .
Thecodont (replacement tooth underneath deeply embedded alligator) vs. acrodont (shallow sockets with crest attachment at very surface of gums snake) vs. pleurodont (tooth attached medial side of dentary lizards)
Can you calculate the dental formulae of a mammalian skull?
incisors, canines,
top number is upper jaw bottom is lower and then only count half the jaw
mammals- canines, incisors, molars.mammals: incisors- front scissors act like canines , canines- puncturing and holding, premolars like molars, and molars (crushing and grinding)
Compare and contrast the characteristics of cartilage and bone
Bone and cartilage are supportive tissues,
Cartilage and bone have shared features of mineralized connective tissues with inorganic salts and proteins in the extracellular matrix ECM
cartilage has chondrocyte cell type, ECM- ground substance: chondroitin, sulfate Protein: collagen, avascular, and disorganized
Bone: have osteocyte cell types, ECM: ground substance: calcium phosphate with proteins of collagen, and its high vascular, and very organized into osteons.
Which are the different types of car/lage and where can they be found?
Three kinds of cartilage: hyaline cartilage (little cartilage) found mostly embryonically as the predecessor of bone formation, fibrocartilage have a lot of collagen (knee joints and hips intervertebral disc), and elastic cartilage having elastin instead of collagen (ears and tip of nose, and pubic symphysis)
What are the parts of a long bone? Why do bones break and how do they heal?
Spongy bone towards end and has compact or that is dense on the very outside. three parts to bone, epiphysis- end of bone, metaphysis- where bone is growing from, diaphysis-medullary cavity is found hollow.
architecture of bones has layers but will not spread because it was a different layer stopping the crack from spreading. majority of force on bone is at edges and on outside of bony structure a lot of forces acting more strongly not acting uniformly throughout all bone and if you make that very strong can get away with hollow structure making it light?
bone breaks: break bone shear capillaries forming clot and start formation of secondary cartilage going into clot and becoming ossified forming spicules and infiltrating throughout all of the bone until you are essentially fully healed. since they have to fight against gravity so the bones became stronger vertically because of compression. squish material and see how much pressure there is before it shatters. compressive strength in bones is the highest for every material comparing concrete, granite and is less than cast iron.
bones always being replaced and changing based on daily impact and exercise making bones recruit more calcium phosphate and need to keep them stronger as well as normal wear and tear
• How does terrestrial locomotion affect evolution of vertebrae?
vertebral column functional evolution: initially, spinal cord and dorsal aorta protection with dorsal (spporting and protecting nerve cord) and hemal arched (dorsal aorta) appeared first, and centra (main body of vertebrate in the middle of element supporting arches) formed secondarily to support arches/fin. Secondarily, muscle attaches to the site with myoseptum and how divided into myoseptum.
No longer just protective of internal and important vessels but must function as suspension of body and for locomotion.
favored an elnrlarged centrumand disappearance of the notochord, and favored the enlargement of one or two parts of the centrum and increase strength and reduced flexibility to support weight on land. reptiles, birds, and all mammals lost the intercentrum completely making a little less flexible. . amniotes have large neural arches (allow for more muscle attachment as over more land and water)
