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Comparative AnatomyComparative AnatomyBoneBone
Kardong Kardong Chapters 7, 8, & 9Chapters 7, 8, & 9
Part 9Part 9
Organization of Skeletal TissuesOrganization of Skeletal Tissues
Figure 9.1.
Bone LegacyBone Legacy
Exoskeleton or dermal skeletonExoskeleton or dermal skeleton Dermal bony armor of ostracodermsDermal bony armor of ostracoderms Bony scales in ancient fishBony scales in ancient fish
Cranial dermal armor arose from neural crest Cranial dermal armor arose from neural crest cellscells
EndoskeletonEndoskeleton Internal to skinInternal to skin Were once exoskeleton Were once exoskeleton
Ex: clavicle, nasal, frontal, and parietal boneEx: clavicle, nasal, frontal, and parietal bone
Other endoskeletal elements were never part of Other endoskeletal elements were never part of the dermal skeletonthe dermal skeleton Ex: scapula, vertebrae, ribs, sternum, brain case, and Ex: scapula, vertebrae, ribs, sternum, brain case, and
extremity bonesextremity bones
Bone EvidenceBone Evidence
All bone develops from mesenchymeAll bone develops from mesenchyme Neural crest cellsNeural crest cells Membrane boneMembrane bone- arises from mesenchyme - arises from mesenchyme
without passing through cartilaginous without passing through cartilaginous intermediateintermediate exoskeletonexoskeleton
Replacement boneReplacement bone- arises from existing - arises from existing cartilagecartilage endoskeletonendoskeleton
Endoskeletal TissuesEndoskeletal Tissues Visceral SkeletonVisceral Skeleton
Jaw cartilages and middle ear bonesJaw cartilages and middle ear bones Weberian ossicles of fish (are referred to as ear ossicles)Weberian ossicles of fish (are referred to as ear ossicles) Derived from transverse processes of anterior most vertebraeDerived from transverse processes of anterior most vertebrae
Somatic SkeletonSomatic Skeleton Remaining internal bones developing from Remaining internal bones developing from
mesoderm propermesoderm proper SclerotomeSclerotome of somite of somite
Axial SkeletonAxial Skeleton Appendicular SkeletonAppendicular Skeleton
Vertebrae DevelopmentVertebrae Development
Arise from sclerotome cells of somitesArise from sclerotome cells of somites MorphogenesisMorphogenesis
Sclerotome divides into posterior and anterior halvesSclerotome divides into posterior and anterior halves Halves join with segments of adjacent sclerotomesHalves join with segments of adjacent sclerotomes Centrum formed from junction Centrum formed from junction Vertebrae are intersegmentalVertebrae are intersegmental Myotome doesn’t moveMyotome doesn’t move Posterior segment forms costal processPosterior segment forms costal process
Site of rib attachmentSite of rib attachment
Figure 9.3. Developing vertebral column showing intersegmental position (see book figure 8.12).
Figure 9.2. (a) sclerotome divides (b) halves join with adjacent halves of next sclerotome (c) junction forms centrum (see book figure 8.12)
Vertebrae Development (cont’d.)Vertebrae Development (cont’d.)
Axial Skeleton VertebraeAxial Skeleton Vertebrae Cartilaginous or bonyCartilaginous or bony From occipital region to tailFrom occipital region to tail Vertebrae types based on centrum structureVertebrae types based on centrum structure
Centrum is common feature in all vertebraeCentrum is common feature in all vertebrae
Centrum StructureCentrum Structure Acelous- flat anterior and posterior surfaceAcelous- flat anterior and posterior surface
MammalsMammals Amphicelous- concavities of anterior and posterior Amphicelous- concavities of anterior and posterior
surfacessurfaces Fish, primitive salamandersFish, primitive salamanders
Procelous- concavity on anterior surfaceProcelous- concavity on anterior surface Most reptilesMost reptiles
Opisthocelous- concavity of posterior surfaceOpisthocelous- concavity of posterior surface Most salamandersMost salamanders
Heterocelous- saddle-shapedHeterocelous- saddle-shaped Neck of birds and turtlesNeck of birds and turtles
Figure 9.4. Vertebral types based on articular surface of centra (book figure 8.4).
Vertebrae EvolutionVertebrae Evolution Transition from crossopterygians Transition from crossopterygians
to labyrinthodontsto labyrinthodonts Different types of vertebrae Different types of vertebrae
came from primitive, came from primitive, rachitomous labyrinthodont rachitomous labyrinthodont vertebraevertebrae
Two pleurocentra and U-shaped Two pleurocentra and U-shaped hypocentrumhypocentrum
Hypocentrum is lost and Hypocentrum is lost and pleurocentrem enlarges and gives pleurocentrem enlarges and gives rise to centrum of modern amnioterise to centrum of modern amniote
Figure 9.5. Modifications from labyrinthodont to modern amniote vertebrae. Hypocentrum is diagonal lines. Pleurocentrum is red (see book figure 8.3).
Vertebrae GroupingVertebrae Grouping
Grouped according to body regionGrouped according to body region AmphibiansAmphibians
First to possess a cervical vertebraeFirst to possess a cervical vertebrae
Figure 9.6. Single cervical vertebrae of anuran (book figure 8.13).
Figure 9.7. Regions of vertebral column.
Reptile VertebraeReptile Vertebrae
Atlas as 1st and axis as Atlas as 1st and axis as 2nd cervicals2nd cervicals
Turtle: 8 cervicals, 2 Turtle: 8 cervicals, 2 sacrals, 10 dorsals, 16-sacrals, 10 dorsals, 16-30 caudals30 caudals
Alligator: 8 cervicals, 11 Alligator: 8 cervicals, 11 thoracic, 5 lumbar, 2 thoracic, 5 lumbar, 2 sacrals, up to 40 sacrals, up to 40 caudalscaudals
Figure 9.9. Dorsal view of sacral vertebrae of vertebrates.
Figure 9.8. atlas and axis cervical vertebrae.
Bird VertebraeBird Vertebrae
Possess atlas and axisPossess atlas and axis 13-14 free cervicals, 4 fused thoracics, 13-14 free cervicals, 4 fused thoracics,
fused synsacrum, free caudals, pygostylefused synsacrum, free caudals, pygostyle
Figure 9.10. Pigeon vertebral column (see book figure 8.31).
SynsacrumSynsacrum Fuses with pelvic boneFuses with pelvic bone Reduction in bone massReduction in bone mass
Figure 9.12. Synsacrum and pelvic girdle left lateral (a) and ventral (b) views (book figure 8.31).
Figure 9.11. Pigeon skeleton: trunk, tail, and pectoral girdle.
Mammal VertebraeMammal Vertebrae
Most species have 7 cervicalsMost species have 7 cervicals 12 thoracic and 5 lumbar compose dorsal 12 thoracic and 5 lumbar compose dorsal
vertebraevertebrae ancestral mammals possessed ~ 27 presacralsancestral mammals possessed ~ 27 presacrals sacrum 2-5 fused vertebrae (ankylosed)sacrum 2-5 fused vertebrae (ankylosed) caudals are variablecaudals are variable
primates have 2-5 fused into coccyxprimates have 2-5 fused into coccyx
RibsRibs Dogfish- develop dorsal ribsDogfish- develop dorsal ribs Most teleost- develop ventral ribsMost teleost- develop ventral ribs Tetrapods- have dorsal and ventral ribsTetrapods- have dorsal and ventral ribs
Current theory is that the tetrapod rib is homologous Current theory is that the tetrapod rib is homologous to the dorsal rib of fishesto the dorsal rib of fishes
Primitive tetrapods have bicipital ribs - 2 portions Primitive tetrapods have bicipital ribs - 2 portions articulate with vertebraearticulate with vertebrae
Tuberculum- dorsal headTuberculum- dorsal head Capitulum- ventral headCapitulum- ventral head
Figure 9.13. Dorsal and ventral ribs (book figure 8.6 and 8.7).
Agnathans- no ribsAgnathans- no ribs Amphibians- ribs never Amphibians- ribs never
reach sternumreach sternum Birds- flat processes Birds- flat processes
extending off ribs extending off ribs posteriorly (uncinate posteriorly (uncinate processes)processes)
Figure 9.14. Uncinate processes of bird (see bookfigure 8.8).
Figure 9.15. Vertebrae and ribs of alligator (book figure 8.2).
SternumSternum Strictly a tetrapod structureStrictly a tetrapod structure Amphibians- poorly formedAmphibians- poorly formed Reptiles - cartilaginous platesReptiles - cartilaginous plates
Snakes, legless lizards, turtles have no sternumSnakes, legless lizards, turtles have no sternum Alligator- extends down bellyAlligator- extends down belly
Ribs fused it sternumRibs fused it sternum GastraliaGastralia
Figure 9.16. Ribs and gastralia of alligator (book figure8.2).
Birds- unusual, keeled sternum in Birds- unusual, keeled sternum in carinatescarinates
Mammals- well developed sternumMammals- well developed sternum Rod shapedRod shaped Segments: manubrium, sternebrae, Segments: manubrium, sternebrae,
xiphisternum and xiphoid processxiphisternum and xiphoid process
Figure 9.18. Tetrapod sterna (book figure 8.8).
Figure 9.17. Keeled sternum of bird (book figure 8.8).
Heterotopic BoneHeterotopic Bone
Develop by endochondral or intramembranous Develop by endochondral or intramembranous ossification ossification
In areas subject to continual stressIn areas subject to continual stressEx: Os cordis, rostral bone, os penis, os clitoridisEx: Os cordis, rostral bone, os penis, os clitoridis
Os cordis- interventricular septum in deer Os cordis- interventricular septum in deer heartheart
Rostral bone- snout of pigRostral bone- snout of pig Os penis (baculum)- embedded in penis of Os penis (baculum)- embedded in penis of
lower primateslower primates Os clitoridis- embedded in clitoris of ottersOs clitoridis- embedded in clitoris of otters Others include falciform, sesamoid, patella, Others include falciform, sesamoid, patella,
pisiformpisiform
Figure 9.19. Heterotopic bones.
Skull and Visceral SkeletonSkull and Visceral Skeleton Two functionally independent cartilaginous components derived from Two functionally independent cartilaginous components derived from
replacement bonereplacement bone1. Neurocranium 1. Neurocranium
(= chondrocranium)(= chondrocranium)2. Splanchnocranium2. Splanchnocranium
Figure 9.20. Dog skull. Sources ofthe various bones are outlined: dermatocranium (pink),neurocranium (= chondrocranium)-(blue); splanchnocranium (yellow)
Neural Crest Contributions to the Skull
Figure 9.21.
NeurocraniumNeurocranium Protects brain and anterior part of spinal cordProtects brain and anterior part of spinal cord Sense organ capsulesSense organ capsules Cartilaginous brain case is embryonic adaptationCartilaginous brain case is embryonic adaptation Four ossification centersFour ossification centers
Figure 9.22. Development of cartilaginous neurocranium (book figure 7.3).
Neurocranium Ossification CentersNeurocranium Ossification Centers
Occipital regionOccipital region Sphenoid regionSphenoid region Ethmoid regionEthmoid region Otic regionOtic region
Figure 9.23. Neurocranium of human skull.
Occipital RegionOccipital Region Basioccipital, 2 exoccipitals, Basioccipital, 2 exoccipitals,
supraoccipitalsupraoccipital Forms single occipital bone in mammalsForms single occipital bone in mammals
Sphenoid RegionSphenoid Region Basisphenoid, orbitosphenoid, Basisphenoid, orbitosphenoid,
presphenoid, laterosphenoidpresphenoid, laterosphenoid Fuse to form one sphenoid Fuse to form one sphenoid
bone in mammalsbone in mammals
Figure 9.24. Sphenoid bone.
Figure 9.25. Human skull (a) cribriform plate (b) frontal bone (c) temporal bone (d) ethmoid bone (e) sphenoid bone (f) foramen magnum.
Figure 9.26. Sphenoid bone.
Ethmoid RegionEthmoid Region Anterior to sphenoidAnterior to sphenoid Cribriform plate, olfactory foramina, terminals, Cribriform plate, olfactory foramina, terminals,
mesamoid mesamoid Fuse to form ethmoid in mammalsFuse to form ethmoid in mammals
Otic Region Otic Region Three bones in tetrapodsThree bones in tetrapods
ProoticProotic OpisthoticOpisthotic EpioticEpiotic
Unite to form petrosal bone in birds and mammalsUnite to form petrosal bone in birds and mammals Forms temporal in mammalsForms temporal in mammals
Figure 9.28. Multiple nature of temporal bone of mammals (see book figure 7.53).
Figure 9.27. Temporal bone of human skull (book figure 9.28).
Figure 9.29. Intramembranous ossification of human skull. Embryonic, cartilaginous neurocranium is black. Neurocranial bones are red. Other is dermal mesenchyme.
SplanchnocraniumSplanchnocranium Viscerocranium, although a Viscerocranium, although a
misnomer.misnomer.- Visceral arches- Visceral arches- Branchial region- Branchial region
Figure 9.31. Splanchnocranium of human. Skeletal derivatives of 2nd through 5th pharyngeal arches (see book Table 7.2).
Figure 9.30. Primitive splanchnocranium.
1st visceral arch- mandibular1st visceral arch- mandibular Meckel’s cartilage Meckel’s cartilage malleus malleus Palatoquadrate (quadrate) Palatoquadrate (quadrate) incus incus
2nd visceral arch- hyoid2nd visceral arch- hyoid hyomandibula hyomandibula columella (stapes) columella (stapes) ceratohyal ceratohyal styloid process and anterior styloid process and anterior
horn of hyoidhorn of hyoid basihyal basihyal body of hyoid body of hyoid
Figure 9.32. Caudal end of Meckel’s cartilage and developing middle ear cavity.
Viscerocranial DerivativesViscerocranial Derivatives
Alisphenoid- part of sphenoidAlisphenoid- part of sphenoid Malleus, incus- 1st archMalleus, incus- 1st arch Stapes- 2nd archStapes- 2nd arch Styloid- 2nd archStyloid- 2nd arch Hyoid- mainly basihyalHyoid- mainly basihyal
Figure 9.33. Derivatives of the human visceral skeleton (red).
Figure 9.34. Skeletal derivatives of pharyngeal arches (book Table 7.2).
DermatocraniumDermatocranium Membrane bone, not replacement boneMembrane bone, not replacement bone Dermal bones of skullDermal bones of skull Upper jaw and face, palates, mandibleUpper jaw and face, palates, mandible
Figure 9.35. Pattern that tetrapod dermatocrania (see book figure 7.10).
Figure 9.37. Hypothetical derivations of skull bones. (Box Essay 7.1)
Figure 9.36. Dog skull showing dermatocranium (pink), chondrocranium (blue), and splanchnocranium (yellow).
DermatocraniumDermatocranium (con’t.)(con’t.)
Dermatocranial ElementsDermatocranial Elements Nasal, frontal, parietal, squamosal (facial and roofing bones)Nasal, frontal, parietal, squamosal (facial and roofing bones) Dentary Dentary Vomer, palatine, pterygoid (primary palate) Vomer, palatine, pterygoid (primary palate) Premaxilla, maxillary, jugal (secondary palate) Premaxilla, maxillary, jugal (secondary palate)
Figure 9.38. Lizard skull.
Evolution of Mammalian Middle Ear BonesEvolution of Mammalian Middle Ear Bones
Figure 9.39. (book figure 7.55).
Phylogeny of the Splanchnocranium
Figure 9.40. (book figure 7.66).
Appendicular SkeletonAppendicular Skeleton Pectoral GirdlePectoral Girdle Pelvic GirdlePelvic Girdle AppendagesAppendages Adaptations for SpeedAdaptations for Speed
Pectoral GirdlePectoral Girdle 2 sets of elements: cartilage or replacement 2 sets of elements: cartilage or replacement
bone/membrane bonebone/membrane bone
Replacement bonesReplacement bones Coracoid, scapula, suprascapulaCoracoid, scapula, suprascapula
Membrane bonesMembrane bones Clavicle, cleithrum, supracleithrumClavicle, cleithrum, supracleithrum
Figure 9.41. Pectoral girdle along phylogenetic lines. Dermal bones are red. Replacement bones are black.
Reduction in number of Reduction in number of bones through evolutionbones through evolution
Shark- only cartilagenous Shark- only cartilagenous componentscomponents
Alligator- retains only Alligator- retains only replacement bone elements, no replacement bone elements, no dermal bonedermal bone
Mammals Mammals Scapula of replacement bone Scapula of replacement bone Clavicle of membrane boneClavicle of membrane bone
Birds- two clavicles form furcula Birds- two clavicles form furcula (wishbone)(wishbone)
(a)
(b)
Figure 9.42. Pectoral girdles of (a) Polypterus and (b) shark.. Dermal bones are red. Replacement bones are black.
Fish – Tetrapod Transition
Figure 9.43. (book figure 9.16).
Summary of Pectoral Girdle Evolution
Figure 9.44. (book figure 9.19).
Pelvic GirdlePelvic Girdle
No dermal elementsNo dermal elements Three replacement bonesThree replacement bones
Ilium, ischium, pubisIlium, ischium, pubis Triradiate pelvic girdle- Triradiate pelvic girdle-
alligator and dinosauralligator and dinosaur
Figure 9.45. Left halves of pelvic girdles showing parallel evolution.
Summary of Pelvic Girdle Evolution
Figure 9.46. (bookfigure 9.21).
AppendagesAppendages
Single unit most medial in both fore and hind limbsSingle unit most medial in both fore and hind limbs Two units in distal region of fore and hind limbTwo units in distal region of fore and hind limb
Figure 9.47. Dorsal view of left forelimb or forefin of Devonian tetrapods.
Figure 9.48. Cladogram of lobe-Fin fishes and amphibians.
Figure 9.49. Basic organization of fore- and hindlimb (book figure 9.23).
Small set of bones at wrist and ankleSmall set of bones at wrist and ankle Pentameristic pattern of phalangesPentameristic pattern of phalanges Reduction in number and position of Reduction in number and position of
phalangesphalanges
Figure 9.50. Evolution of fins to limbs.
Figure 9.51. Adaptations in secondarily aquatic tetrapods.(book figure 9.30)
Adaptations for SpeedAdaptations for Speed
PlantigradePlantigrade Flat on the groundFlat on the ground Primates Primates
DigitigradeDigitigrade ElevatedElevated CarnivoresCarnivores
UnguligradeUnguligrade Reduction in digitsReduction in digits Two typesTwo types Figure 9.52. Plantigrade, digitigrade, and unguligrade
feet. Ankle bones are black. Metatarsals are gray.
Unguligrade AdaptationsUnguligrade Adaptations Reduction in digitsReduction in digits
PerissodactylPerissodactyl Odd toedOdd toed Mesaxanic footMesaxanic foot
- Weight on enlarged middle - Weight on enlarged middle digitdigit
Ex: horseEx: horse
ArtidodactylArtidodactyl Even toedEven toed Paraxonic footParaxonic foot
- Weight equally distributed - Weight equally distributed on 3on 3rdrd and 4 and 4thth digits digits
Ex: camelEx: camel
Figure 9.53. Unguligrade adaptations in horse and camel. Bones lost are white (see book figure 9.39).
Skeletal Adaptations for Digging
Figure 9.54. (book figure 9.58).
Locomotion Without LimbsLocomotion Without Limbs
SerpentineSerpentine Lateral undulationLateral undulation Wave motionWave motion Minimum 3 contact pointsMinimum 3 contact points
RectilinearRectilinear Straight lineStraight line Scutes on belly liftScutes on belly lift Costocutaneous muscles Costocutaneous muscles
move the skinmove the skinFigure 9.55. Serpentine locomotion (a) and rectilinear locomotion (b & c)
(a)
(b)
(c)
SidewindingSidewinding Minimum 2 contact pointsMinimum 2 contact points Adaptation in sandy habitats Adaptation in sandy habitats
ConcertinaConcertina Minimum 2 contact pointsMinimum 2 contact points Allows snake to move up Allows snake to move up
guttergutter
Locomotion Without Limbs (cont’d.)Locomotion Without Limbs (cont’d.)
(a) (b)
Figure 9.56. Sidewinding locomotion (a) and concertina locomotion (b)
Brachiation: Human Limb Engineering
Figure 9.57. (book page 354).
Five to 10 million years have passedsince distant human ancestors swung through trees (Kardong, 2013).