Comparative Anatomy Bone
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Transcript Comparative Anatomy Bone
Comparative Anatomy
Bone
Note Set 7
Chapters 7, 8, & 9
Bone Legacy
Exoskeleton or dermal skeleton
Dermal bony armor of ostracoderms
Bony scales in ancient fish
Cranial dermal armor arose from neural crest cells
Endoskeleton
Internal to skin
Where once exoskeleton
Ex: clavicle, nasal, frontal, and parietal bone
Other endoskeletal elements were never part of
the dermal skeleton
Ex: scapula, vertebrae, ribs, sternum, brain case, and
extremity bones
Bone Evidence
All bone develops from mesenchyme
Neural crest cells
Membrane bone- arises from mesenchyme
without passing through cartilaginous
intermediate
exoskeleton
Replacement bone- arises from existing cartilage
endoskeleton
Endoskeletal Tissues
Visceral Skeleton
Jaw cartilages and ear ossicles
Weberian ossicles of fish (ear ossicles)
Derived from transverse processes of anterior most
vertebrae
Somatic Skeleton
Remaining internal bones developing from mesoderm
proper
Somite and scleratome
Axial Skeleton
Appendicular Skeleton
Vertebrae Development
Arise from sclerotome cells of somites
Morphogenesis
Sclerotome divides into posterior and anterior halves
Halves join with segments of adjacent sclerotomes
Centrum formed from junction
Vertebrae are intersegmental
Myotome doesn’t move
Posterior segment forms costal process
Site of rib attachment
Vertebrae Development
Figure 9.1: (a) sclerotome divides (b) halves
join with adjacent halves of next sclerotome
(c) junction forms centrum.
Figure 9.2: Developing vertebral column
showing intersegmental position.
Axial Skeleton Vertebrae
Cartilaginous or bony
From occipital region to tail
Vertebrae types based on centrum structure
Centrum is common feature in all vertebrae
Centrum Structure
Acelous- flat anterior and posterior surface
Mammals
Amphicelous- concavities of anterior and posterior
surfaces
Fish, primitive salamanders
Procelous- concanvity on anterior surface
Most reptiles
Opisthocelous- concavity of posterior surface
Most salamanders
Heterocelous- saddle-shaped
Neck of birds and turtles
Figure 9.3: Vertebral types based on articular surface of centra.
Vertebrae Evolution
Transition from crossopterygians
to labyrinthodonts
Different types of vertebrae
came from primitive,
rachitomous labyrinthodont
vertebrae
Two pleurocentra and U-shaped
hypocentrum
Hypocentrum is lost and
pleurocentrum enlarges and gives
rise to centrum of modern
amniote
Figure 9.4: Modifications from
labyrinthodont to modern amniote
vertebrae. Hypocentrum is diagonal
lines. Pleurocentrum is red.
Vertebrae Grouping
Grouped according to body region
Amphibians
First to possess a cervical vertebrae
Figure 9.6: Regions
of vertebral column
Figure 9.5: Single
cervical vertebrae of
anuran.
Reptile Vertebrae
Atlas as 1st and axis as
2nd cervicals
Turtle: 8 cervicals, 2
sacrals, 10 dorsals, 16-30
caudals
Alligator: 8 cervicals, 11
thoracic, 5 lumbar, 2
sacrals, up to 40 caudals
Figure 9.7: atlas and axis cervical vertebrae.
Figure 9.8: Dorsal view of sacral vertebrae of
vertebrates.
Bird Vertebrae
Possess atlas and axis
13-14 free cervicals, 4 fused thoracics,
fused synsacrum, free caudals, pygostyle
Figure 9.9: Pigeon vertebral column.
Synsacrum
Fuses with pelvic bone
Reduction in bone mass
Figure 9.10: Pigeon skeleton: trunk, tail, and
pectoral girdle.
Figure 9.11: Synsacrum and pelvic
girdle left lateral (a) and ventral (b)
views.
Mammal Vertebrae
most have 7 cervicals
12 thoracic and 5 lumbar compose dorsal
vertebrae
ancestral mammals possessed ~ 27 presacrals
sacrum 2-5 fused vertebrae (ankylosed)
caudals are variable
primates have 2-5 fused into coccyx
Ribs
Dogfish- develop dorsal ribs
Most teleost- develop ventral ribs
Tetrapods- have dorsal and ventral ribs
Dorsal ribs lost, enlargement of head of
proximal ribs
2 portions articulate
with vertebrae
Tuberculum- dorsal head
Capitulum- ventral head
Figure 9.12: Rib types - Dorsal and ventral
ribs.
Agnathans- no ribs
Amphibians- ribs never
reach sternum
Birds- flat processes
extending off ribs
posteriorly (unicate
processes)
Figure 9.13: Unicate processes of bird.
Figure 9.14: Vertebrae and ribs of alligator.
Sternum
Tetrapod structure
Amphibians- poorly formed
Reptiles- cartilaginous plates
Snakes, legless lizards, turtles have no sternum
Alligator- extends down belly
Ribs fused it sternum
Gastralia
Figure 9.15: Ribs and gastralia of alligator.
Birds- unusual, keeled sternum in
carinates
Mammals- well developed sternum
Rod shaped
Segments: manubrium, sternebrae,
xiphisternum and xiphoid process
Figure 9.16: Keeled sternum of bird.
Figure 9.17: Tetrapod sterna.
Heterotopic Bone
Develop by endochondral or intramembranous
ossification
In areas subject to continual stress
Ex: os cordis, rostral bone, os penis, os clitoridis
Os cordis- interventricular septum
in deer heart
Rostral bone- snout of pig
Os penis (baculum)- embedded in
penis of lower primates
Os clitoridis- embedded in clitoris
of otters
Others include falciform,
sesamoid, patella, pisiform
Figure 9.18: Heterotopic bones
(book figure 7.11).
Skull and Visceral Skeleton
Two functionally independent cartilaginous
components derived from replacement bone
1. Neurocranium
2. Splanchnocranium
Figure 9.19: Placoderm skull; neurocranium
in blue; splanchnocranium in yellow.
Neurocranium
Protects brain and anterior part of spinal cord
Sense organ capsules
Cartilaginous brain case is embryonic adaptation
Four ossification centers
Figure 9.20: Development of cartilaginous
neurocranium.
Neurocranium Ossification Centers
Occiptial Region
Sphenoid Region
Ethmoid Region
Otic Region
Figure 9.21: Neurocranium of human skull.
Occipital Region
Basioccipital, 2 exoccipitals, suproccipital
Forms single occipital bone in mammals
Sphenoid Region
Basisphenoid, orbitosphenoid,
presphenoid, laterosphenoid
Fuse to form one sphenoid
bone in mammals
Figure 9.22: Sphenoid bone.
Figure 9.23: Human skull (a) cribriform
plate (b) crista galli (c) frontal bone (d)
sphenoid bone (e) temporal bone (f) sella
turcica.
Figure 9.24: Sphenoid bone.
Ethmoid Region
Anterior to sphenoid
Cribriform plate, olfactory foramina, terminals,
mesamoid
Fuse to form ethmoid in mammals
Otic Region
Three bones in tetrapods
Prootic
Opisthotic
Epiotic
Unite to form petrosal bone in birds and mammals
Forms temporal in mammals
Figure 9.25: Temporal bone of human skull.
Figure 9.26: Multiple nature of temporal
bone of mammals.
Figure 9.27: Intramembranous ossification of human
skull. Embryonic, cartilaginous neurocranium is
black. Neurocranial bones are red. Other is dermal
mesenchyme.
Splanchnocranium
Visceral skeleton
Visceral arches
Branchial region
Figure 9.28: Splanchnocranium of human.
Skeletal derivatives of 2nd through 5th
pharyngeal arches.
1st visceral arch- mandibular
Meckel’s cartilage malleus
Pteryoquadrate incus
2nd visceral arch- hyoid
hyomandibula columella (stapes)
ceratohyal styloid process and
anterior horn of hyoid
basihyal body of hyoid
Figure 9.29: Caudal end of Meckel’s
cartilage and developing middle ear
cavity.
Visceral-Cranial Derivatives
Alisphenoid- part of sphenoid
Malleus, incus- 1st arch
Stapes- 2nd arch
Styloid- 2nd arch
Hyoid- mainly basihyal
Figure 9.30: Derivatives of the human
visceral skeleton (red).
Figure 9.31: Skeletal derivatives of pharyngeal arches.
Dermatocranium
Membrane bone, not replacement bone
Dermal bones of skull
Upper jaw and face, palates, mandible
Figure 9.32: Pattern that tetrapod dermatocrania may have evolved.
Dermatocranium (cont.)
Figure 9.33: Dog skull showing dermatocranium
(pink), chondrocranium (blue), and
splanchnocranium (yellow).
Figure 9.34: Endochondral bones (red) of
mammalian skull.
Dermatocranial Elements
Nasal
Squamosal
Secondary palate- premaxilla, maxilla, jugal
Primary palate- vomer, palatine, pterygoid
Neurocranial Elements
Cribriform
Ethmoid
Otic complex
Temporal bone
Splanchnocranial Elements
Maleus, incus, stapes
Styloid process- hyoid
Visceral Arches of Man
Styloid processes
Body of hyoid
Thyroid
Cricoid
Middle Ear Bones
Hammer (malleus_
Anvil (incus)
Stirrup (stapes)
Not homologous to weberian ossicles in teleost
fish
Modified transverse processes of anteriormost
vertebrae in some fishes.
Appendicular Skeleton
Pectoral Girdle
Pelvic Girdle
Appendages
Adaptations for Speed
Pectoral Girdle
2 sets of elements: cartilage or
replacement bone and membrane
bone
Replacement bones
Coracoid, scapula, suprascapula
Membrane bones
Clavicle, cleithrum, supracleithrum
Figure 9.35: Pectoral girdle phylogenetic lines.
Dermal bones are red. Replacement bones are
black.
Reduction in number of
bones through evolution
Shark- only cartilagenous
components
Alligator- retains only
replacement bone elements,
no dermal bone
Mammals
Scapula of replacement bone
Clavicle of membrane bone
Birds- two clavicles fuse to
form furcula (wishbone)
(a)
(b)
Figure 9.36: Pectoral girdles of (a) Polypterus and (b)
shark.. Dermal bones are red. Replacement bones
are black..
Pelvic Girdle
No dermal elements
Three replacement bones
Ilium, ischium, pubis
Triradiate pelvic girdlealligator and dinosaur
Figure 9.37: Left halves of pelvic girdles showing
parallel evolution.
Appendages
Single unit in both fore and hind limbs most medial
Two units in fore and hind limb distal area
Figure 9.38: Dorsal view of left forelimb or forefin of Devonian tetrapods.
Figure 9.40: Left pectoral fin of Devonian fish
[left] and forelimb of early tetrapod [right].
Figure 9.39: Cladogram of lobe-Fin fishes
and amphibians.
Small set of bones at wrist and ankle
Pentameristic pattern of phalanges
Reduction in number and position
of phalanges
Figure 9.41: Evolution of fins to limbs.
Adaptations for Speed
Plantigrade
Flat on the ground
Primates
Digitigrade
Elevated
Carnivores
Unguligrade
Reduction in digits
Two types
Figure 9.42: Plantigrade, digitigrade, and unguligrade
feet. Ankle bones are black. Metatarsals are grey.
Unguligrade Adaptation
Reduction in digits
Perissodactyls
Odd toed
Mesaxanic foot
Weight on enlarged middle
digit
Ex: horse
Artidodactyls
Even toed
Paraxonic foot
Weight equally distributed on
3rd and 4th digits
Ex: camel
Figure 9.43: Unguligrade adaptations in
horse and camel. Bones lost are white.
Locomotion Without Limbs
Serpentine
Lateral undulation
Wave motion
Minimum 3 contact points
(a)
Rectilinear
Straight line
Scutes on belly lift
Costocutaneous muscles
move the skin
(b)
(c)
Figure 9.44: Serpentine locomotion (a) and rectilinear
locomotion (b & c).
Locomotion Without Limbs (cont.)
Sidewinding
Minimum 2 contact points
Adaptation in sandy habitats
Concertina
Minimum 2 contact points
Allows snake to move up
gutter
(a)
(b)
Figure 9.45: Sidewinding locomotion (a) and
concertina locomotion (b).
Literature Cited
Figure 9.1- http://www.brown.edu/Courses/BI0032/bone/axial2.htm
Figure 9.2, 9.3, 9.4, 9.5, 9.8, 9.9, 9.10, 9.11, 9.12, 9.14, 9.16, 9.17, 9.18, 9.20, 9.21, 9.25, 9.26, 9.27, 9.28, 9.29,
9.30, 9.31, 9.32, 9.34, 9.35, 9.36, 9.37, 9.40, 9.42 & 9.43- Kent, George C. and Robert K. Carr.
Comparative Anatomy of the Vertebrates. 9th ed. McGraw-Hill, 2001.
Figure 9.6- http://www.agrabilityproject.org/assistivetech/tips/tractorseat.cfm
Figure 9.7- http://www.spineuniverse.com/displayarticle.php/article2245.html
Figure 9.13- http://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab9b/Bird_Skeleton_1/Bird_Skeleton_1c/bird_skeleton_1c.htm
Figure 9.15- http://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.html
Figure 9.19-Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002.
Figure 9.22- http://www.mlaphil.org/chronicle/20n3/fall2002.htm
Figure 9.23- http://www.staneksoftware.com/anatomy_bowl_content/SkSkull1.htm
Figure 9.24- http://www.upstate.edu/cdb/grossanat/hnsklatsb.shtml
Figure 9.33- Kardong, K. Vertebrates: Comparative Anatomy, Function, Evolution. McGraw Hill, 2002.
Figure 9.38- http://cas.bellarmine.edu/tietjen/images/subphylum_vertefish.htm
Figure 9.39- http://bss.sfsu.edu/holzman/courses/Fall%2003%20project/CAtigersalamander.htm
Figure 9.41- http://pharyngula.org/~pzmyers/MyersLab/teaching/Bi104/l02/fins.html
Figure 9.44- http://www.worldwidesnakes.com/ri-reptile-basic-anatomy-locomotion.php
Figure 9.45 (a)- http://folio.photosource.com/1120
Figure 9.45 (b)- http://voronoi.sbp.ri.cmu.edu/research/rsch_locomotion.html