Vertebrate Systems Summary

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BIO 342Comparative Vertebrate AnatomyLecture Notes 2 - Vertebrate Skeletal Systems

Bone:

inorganic components of bone comprise 60% of the dry weight (largelycalcium hydroxy-appetite crystals) & provide the compressive strength of

bone. The organic component is primarily collagen, which gives bone greattensile strength.

provides support and movement via attachments for soft tissue andmuscle, protects vital organs, is a major site for red marrow for productionof blood cells, and plays a role in the metabolism of minerals such ascalcium and phosphorus.

There are two basic structural types of bone, compact and spongy.Compact bone forms the outer shell of all bones and also the shafts in longbones. Spongy bone is found at the expanded heads of long bones and fillsmost irregular bones. .

Bone formation begins with a blastema (any aggregation of embryonicmesenchymal cells which will differentiate into tissue such as muscle, cartilage, or

bone). These cells then develop into either FIBROBLASTS or OSTEOBLASTS.Fibroblasts form collagen; osteoblasts form bone cells. Together, these formMEMBRANE BONE (bone deposited directed in a blastema).

Intramembranous ossification is the process ofmembrane bone formation. Thisprocess give rise to:

bones of the lower jaw, skull, & pectoral girdle dentin & other bone that develops in the skin vertebrae in some vertebrates (teleosts, urodeles, & apodans)

Endochondral ossificationis the process in which bone is deposited in pre-existing cartilage, & such bone is called REPLACEMENT BONE.

Source:http://training.seer.cancer.gov/module_anatomy/unit3_3_bone_growth.html

Skeletal elements:

Dermal skeletono skin of most living vertebrates has no hard skeletal parts but

dermal bone elements are usually present in the head region

o early vertebrates (ostracoderms) had so much dermal bone theywere called 'armored fishes'

Source: http://www.auburn.edu/academic/classes/zy/0301/Topic3b/Topic3b.html

o after ostracoderms, fish continued to develop much bone in skinbut that bone has become 'thinner' over time

Endoskeletono Somatic - axial & appendicular skeletonso Visceral - cartilage or bone associated with gills & skeletal

elements (such as jaw cartilages) derived from them

Source: http://www.auburn.edu/academic/classes/zy/0301/Topic11/Topic11.html

Dermal bone of fishes:

Basic structure includes lamellar (compact) bone, spongy bone, dentin, &,often, a surface with a layer of enamel-like material

Evolutionary 'trend' = large bony plates giving way to smaller, thinner bonyscales

o Ancient armor - not found on living fisho

Ganoid scales - found only on Latimeria (coelocanth) & sturgeonso Placoid scales - elasmobranchs (diagram to the right; pulp cavity

> dentin layer > enamel)

o Ctenoid & Cycloid scales - modern bony fish

Also check:http://courses.washington.edu/vertebra/453/photos/skin_photos/special_integume

nt1.htm

1 = lamellar bone, 2 = spongy bone, 3 = dentin, 4 = enameloid, & 5 = fibrous plate(collagen)

Source: http://www.uta.edu/biology/restricted/3452int.htm

Tetrapods - retain dermal elements in the skull, jaws, & pectoral girdle

Somatic skeleton = axial skeleton (vertebral column, ribs, sternum, &skull) + appendicular skeleton

Vertebral column:

Vertebrae - consist of a centrum (or body), 1 or 2 arches, plus various processes
http://www.ectsoc.org/reviews/011_roac.htmhttp://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab8/Lab8.htmhttp://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab8/Examples/exmembos.htmhttp://www.douglas.bc.ca/ossification/files/ossification1.htmlhttp://www.bris.ac.uk/Depts/Anatomy/calnet/bones/page5.htmhttp://www.bris.ac.uk/Depts/Anatomy/calnet/bones/page5.htmhttp://www.douglas.bc.ca/ossification/files/ossification2.htmlhttp://www.douglas.bc.ca/ossification/files/ossification2.htmlhttp://training.seer.cancer.gov/module_anatomy/unit3_3_bone_growth.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic3b/Topic3b.htmlhttp://maxshouse.com/anatomy-sleleton.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic11/Topic11.htmlhttp://www.amonline.net.au/fishes/students/scales/index.htmhttp://www.amonline.net.au/fishes/students/scales/index.htmhttp://www.amonline.net.au/fishes/students/scales/ganoid.htmhttp://www.amonline.net.au/fishes/students/scales/placoid.htmhttp://www.amonline.net.au/fishes/students/scales/cyccten.htmhttp://courses.washington.edu/vertebra/453/photos/skin_photos/special_integument1.htmhttp://courses.washington.edu/vertebra/453/photos/skin_photos/special_integument1.htmhttp://www.uta.edu/biology/restricted/3452int.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.htmlhttp://www.uta.edu/biology/restricted/3452int.htmhttp://courses.washington.edu/vertebra/453/photos/skin_photos/special_integument1.htmhttp://courses.washington.edu/vertebra/453/photos/skin_photos/special_integument1.htmhttp://www.amonline.net.au/fishes/students/scales/cyccten.htmhttp://www.amonline.net.au/fishes/students/scales/placoid.htmhttp://www.amonline.net.au/fishes/students/scales/ganoid.htmhttp://www.amonline.net.au/fishes/students/scales/index.htmhttp://www.amonline.net.au/fishes/students/scales/index.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic11/Topic11.htmlhttp://maxshouse.com/anatomy-sleleton.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic3b/Topic3b.htmlhttp://training.seer.cancer.gov/module_anatomy/unit3_3_bone_growth.htmlhttp://www.douglas.bc.ca/ossification/files/ossification2.htmlhttp://www.douglas.bc.ca/ossification/files/ossification2.htmlhttp://www.bris.ac.uk/Depts/Anatomy/calnet/bones/page5.htmhttp://www.douglas.bc.ca/ossification/files/ossification1.htmlhttp://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab8/Examples/exmembos.htmhttp://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab8/Lab8.htmhttp://www.ectsoc.org/reviews/011_roac.htm


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Amphicelouso concave at both endso most fish, a few salamanders (Necturus), & caecilians

Opisthocoelouso convex in front & concave in backo most salamanders

Procelouso concave in front & convex in backo anurans & present-day reptiles Acelouso flat-endedo mammals

Heterocelouso saddle-shaped centrum at both endso birds

Vertebral arches:

Neural arch - on top of centrum Hemal arch (also called chevrons) - beneath centrum in caudal vertebrae

of fish, salamanders, most reptiles, some birds, & many long-tailedmammals

Vertebral processes:

projections from arches & centra some give rigidity to the column, articulate with ribs, or serve as sites of

muscle attachment

Transverse processes - most common type of process; extend laterally from thebase of a neural arch or centrum & separate the epaxial & hypaxial muscles

Diapophyses & parapophyses - articulate with ribs

Prezygapophyses (cranial zygapophyses) & postzygapophyses (caudalzygapophyses) - articulate with one another & limit flexion & torsion of thevertebral column

Vertebral columns:

Cartilaginous fisheso do not have typical fish vertebral columnso vertebrae include neural arches (cartilaginous dorsal plates) &

dorsal intercalary plates are located between successive arches

Teleostso well-ossified amphicelous vertebraeo notochord persists within each centrum (but constricted)o neural arch associated with each centrum & hemal arches in tail

(caudal) vertebrae

Chondrosteans (sturgeons & paddlefish) & modern lungfisheso incomplete centrao notochord is not constrictedo cartilage deposited in notochord sheath provides structural

support

Diplospondyly = 2 centra and 2 sets of arches per body segment; occurs in somefish (including sharks)

Agnathans - only skeletal elements associated with the notochord are paired, lateral

neural cartilages

Vertebral columns of tetrapods

Cervical regiono Amphibians - single cervical vertebra; allows little head movemento Reptiles - increased numbers of cervical vertebrae (usually 7) &

increased flexibility of head

o Birds - variable number of cervical vertebrae (as many as 25 inswans)

o Mammals - usually 7 cervical vertebraeo Reptiles, birds, & mammals - 1st two cervical vertebrae are

modified & called the atlas & axis

atlas - 1st cervical vertebra; ring-like (most of centrumgone); provides 'cradle' in which skull can 'rock' (as whennodding 'yes')

axis - 2nd cervical vertebrao Transverse foramen (#6 in above caudal view of a cervical

vertebra)

found in cervical vertebrae of birds & mammals provides canal for vertebral artery & vein

Dorsal region
http://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.html#typeshttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/_index.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.html#partshttp://www.crnasomeday.com/anatpages/spinal.htmhttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/boonewhitenecturusatlas.htmhttp://www.biology.eku.edu/RITCHISO/554notes1.htmlhttp://www.earthlife.net/mammals/skeleton.htmlhttp://lamar.colostate.edu/~lctodd/cervical.htmhttp://tooldoc.wncc.nevada.edu/figure8.htmhttp://tooldoc.wncc.nevada.edu/figure8.htmhttp://lamar.colostate.edu/~lctodd/cervical.htmhttp://www.earthlife.net/mammals/skeleton.htmlhttp://www.biology.eku.edu/RITCHISO/554notes1.htmlhttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/boonewhitenecturusatlas.htmhttp://www.crnasomeday.com/anatpages/spinal.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.html#partshttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/_index.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic8/Topic8.html#types


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o Dorsals - name given to vertebrae between cervicals & sacralswhen all articulate with similar ribs (e.g., fish, amphibians, &snakes)

o Crocodilians, lizards, birds, & mammals - ribs are confined toanterior region of trunk

thoracic - vertebrae with ribs lumbar - vertebrae without ribs

Sacrum & Synsacrumo sacral vertebrae - have short transverse processes that brace the

pelvic girdle & hindlimbs against the vertebral column

Amphibians - 1 sacral vertebra Living reptiles & most birds - 2 sacral vertebrae Most mammals - 3 to 5 sacral vertebrae

o Sacrum - single bony complex consisting of fused sacralvertebrae; found when there is more than 1 sacral vertebra (seeexamples below):

o Synsacrum found in birds produced by fusion of last thoracics, all lumbars, all

sacrals, & first few caudals

fused with pelvic girdle provides rigid support for bipedal locomotion

Caudal regiono Primitive tetrapods - 50 or more caudal vertebraeo Present-day tetrapods

number of caudal vertebrae is reduced arches & processes get progressively shorter (the last

few caudals typically consist of just cylindrical centra asshown below)

o Anurans - unique terminal segment called the urostyle (section ofunsegmented vertebral column probably derived from separatecaudals of early anurans)

o Birds - last 4 or 5 caudal vertebrae fused to form pygostyle (seedrawing above)

o Apes & humans - last 3 to 5 caudal vertebrae fused to formcoccygeal (or tail bone)

EVOLUTION OF VERTEBRAE

Unlike most tetrapods today, vertebral column of earliest tetrapods did notconsist of 1 bone/body segment.

Crossopterygian vertebrae consisted of an hypocentrum (a large, wedge-shaped piece) plus 2 pleurocentra (smaller, intersegmental pieces). Thistype of vertebra is called a rachitomous vertebra.

The 'trend' in vertebra evolution has been for pleurocentra to increase insize (and, of course, for the hypocentrum to decrease in size). This trend isapparent in this diagram:

Cross-hatched areas = hypocentrum; black areas = pleurocentrum.

Ribs - may be long or short, cartilaginous or bony; articulate medially withvertebrae & extend into the body wall

A few teleosts - have 2 pair of ribs for each centrum of trunk (dorsal ribseparates epaxial & hypaxial muscles)

Most teleosts - ventral ribs only Sharks - dorsal ribs only Agnathans - no ribs Tetrapods - ribs usually articulate with vertebrae in moveable joints (see

above drawing)

o Early tetrapods - ribs articulated with every vertebra from theatlas to the end of the trunk

oLater tetrapods - long ribs limited to thoracic region

Thoracic ribs - most composed of a dorsal element(vertebral rib) & a ventral element (sternal rib)

Sternal rib - may be ossified (birds) or remaincartilaginous (mammals); usually articulate with sternum(except 'floating ribs')

Uncinate processes - found in birds; provides rib-cagewith additional support

Sternum - strictly a tetrapod structure &, primarily, an amniote structure.

Amphibians - no sternum in early amphibians &, among present-dayamphibians, only anurans have one

Amnioteso sternum is a plate of cartilage & replacement boneo sternum articulates with the pectoral girdle anteriorly & with a

variable number of ribs

Useful link:

BIO 342Comparative Vertebrate AnatomyLecture Notes - Skeletal System II (Skull)

The Vertebrate Skull consists of:

1 - neurocranium (also called endocranium or primary braincase)
http://lamar.colostate.edu/~lctodd/thoracic.htmhttp://lamar.colostate.edu/~lctodd/lumbars.htmhttp://lamar.colostate.edu/~lctodd/sacrum.htmhttp://biology.nebrwesleyan.edu/Courses/Labs/Biology_of_Animals/Image%20Web%20Pages/Chordata/Frog_Skeleton.htmlhttp://www.bio.psu.edu/faculty/strauss/anatomy/skel/sacrum.htmhttp://www.bio.psu.edu/faculty/strauss/anatomy/skel/skeletal.htmhttp://www.biology.eku.edu/ritchiso/342notes2.htm#birds#birdshttp://www.biology.eku.edu/ritchiso/342notes2.htm#birds#birdshttp://www.bio.psu.edu/faculty/strauss/anatomy/skel/skeletal.htmhttp://www.bio.psu.edu/faculty/strauss/anatomy/skel/sacrum.htmhttp://biology.nebrwesleyan.edu/Courses/Labs/Biology_of_Animals/Image%20Web%20Pages/Chordata/Frog_Skeleton.htmlhttp://lamar.colostate.edu/~lctodd/sacrum.htmhttp://lamar.colostate.edu/~lctodd/lumbars.htmhttp://lamar.colostate.edu/~lctodd/thoracic.htm


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2 - dermatocranium (membrane bones)

3 - splanchnocranium (or visceral skeleton)

Neurocranium:

1 - protects the brain

2 - begins as cartilage that is partly or entirely replaced by bone (except incartilaginous fishes)

o Cartilaginous stage: neurocranium begins as pair of parachordal & prechordal

cartilages below the brain

parachordal cartilages expand & join; along with thenotochord from the basal plate

prechordal cartilages expand & join to form an ethmoidplate

Cartilage also appears in the olfactory capsule (partially surrounding the

olfactory epithelium)

otic capsule (surrounds inner ear & alsodevelops into sclera of the eyeball)

Completion of floor, walls, & roof: Ethmoid plate - fuses with olfactory capsules Basal plate - fuses with otic capsules

Further development of cartilaginous neurocranium =development of cartilaginous walls (sides of braincase) &,in cartilaginous fishes, a cartilaginous roof over the brain

Cartilaginous fishes - retain a cartilaginous neurocranium (or chondrocranium)throughout life

Bony fishes, lungfishes, & most ganoids - retain highly cartilaginous neurocraniumthat is covered by membrane bone

Cyclostomes - the several cartilaginous components of the embryonic neurocraniumremain in adults as more or less independent cartilages

Source: http://gwis2.circ.gwu.edu/~atkins/newwebpages/Skeletal/Skeletable.html

Other bony vertebrates - embryonic cartilaginous neurocranium is largely replacedby replacement bone (the process of endochondral ossification occurs almost

simultaneously at several ossification centers)

Neurocranial ossification centers:

1 - occipital centers

cartilage surrounding the foramen magnum may be replaced by as manyas four bones:

o basioccipitalo exoccipital (2)o supraoccipital

Mammals - all 4 occipital elements typically fuse to form a single occipitalbone (pictured below)

Tetrapods - neurocranium articulates with the 1st vertebra via 1 (reptilesand birds) or 2 (amphibians and mammals) occipital condyles (see humanskull below)

2 - Sphenoid centers form:

basisphenoid bone (anterior to basioccipital) presphenoid bone side walls above basisphenoid & presphenoid form:

o orbitosphenoido pleurosphenoido alisphenoid

3 - Ethmoid centers tend to remain cartilaginous & form

anterior to sphenoid cribiform plate of ethmoid & several conchae (or ethmoturbinal bones)

The ethmoid region is clearly visible within the bisected skull above. In mostmammals, the nasal chamber

is large & filled with ridges from the ethmoid bones called the turbinals orethmoturbinals. These bones are covered with

olfactory epithelium in life and serve to increase the surface area forolfaction (i.e., a more acute sense of smell).

Another ethmoid bone, the cribiform plate, separates the nasalchamber from the brain cavity within the skull.

4 - Otic centers - the cartilaginous otic capsule is replaced in lower vertebrates byseveral bones:

prootic opisthotic
http://www.hopkinsmedicine.org/craniofacial/LynmProject/BSC/BSC2.HTM#FIGURE4http://home.houston.rr.com/vnotes/Bones/Braincase.htmlhttp://tolweb.org/tree?group=Craniata&contgroup=Chordatahttp://gwis2.circ.gwu.edu/~atkins/newwebpages/Skeletal/Skeletable.htmlhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://home.houston.rr.com/vnotes/Bones/Ethmoid1.gifhttp://home.houston.rr.com/vnotes/Bones/Ethmoid1.gifhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://home.houston.rr.com/vnotes/Bones/Occipital7.gifhttp://gwis2.circ.gwu.edu/~atkins/newwebpages/Skeletal/Skeletable.htmlhttp://tolweb.org/tree?group=Craniata&contgroup=Chordatahttp://home.houston.rr.com/vnotes/Bones/Braincase.htmlhttp://www.hopkinsmedicine.org/craniofacial/LynmProject/BSC/BSC2.HTM#FIGURE4


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epiotic One or more of these may unite with adjacent replacement or membrane

bones:

o Frogs & most reptiles - opisthotics fuse with exoccipitalso Birds & mammals - prootic, opisthotic, & epiotic unite to form a

single petrosal bone; the petrosal, in turn, sometimes fuses withthe squamosal to form the temporal bone

DERMATOCRANIUM - lies superficial to neurocranium & forms:

1 - bones that form the roof of the brain & contribute to the lateral walls of the skull

2 - bones of the upper jaw

3 - bones of the palate(s)

4 - opercular bones

Basic pattern of "roofing bones":

crossopterygians - a series of paired & unpaired bones along mid-dorsalline of skull (below left)

labyrinthodonts - unpaired bones lost & a series of paired bones resulted(nasals, frontals, parietals, & dermoccipitals) (below right)

Fontanels = 'soft spots'o occur when neurocranium is incomplete dorsally (e.g., teleosts &

tetrapods)

o can be felt in head until the membranes under the skin haveossified

Bones of the upper jaw

Pterygoquadrate (palatoquadrate) cartilage - 1st upper jaw that vertebrateembryos develop

o Cartilaginous fishes - palatoquadrate is the only upper jaw thatdevelops

o Bony vertebrates - the palatoquadrate becomes covered withdermal bones (premaxillae & maxillae) that make up the adultupper jaw

Palatal bones - the floor on which the brain rests is at the same time the roof of

the oral cavity in fishes & amphibians (primary palate)

Sharks - cartilaginous bony vertebrates - membrane bones form Birds, mammals, & some reptiles - a secondary ('false') palate develops

creating a horizontal partition that separates the oral cavity into nasal &oral passages. The secondary palate is formed from processes of thepremaxillae, maxillae, and palatines.

Opercular bones

Operculum = fold of the hyoid arch that extends back over the gill slits inholocephalans & bony fishes

Tetrapods - no vestiges of opercular bones remainBIO 342Comparative Vertebrate AnatomyLecture Notes 4 - Skeletal System III

VISCERAL SKELETON (or SPLANCHNOCRANIUM)

skeleton of the pharyngeal archeso Fishes - skeleton of the jaws & gill archeso Tetrapods - skeleton modified for new functions

Fish visceral skeleton - consists of 7 sets of paired cartilages in the 7 visceral arches& a series of mid-ventral cartilages (basihyal & basibranchials) in the pharyngealfloor

Bony fishes

visceral skeleton resembles that of sharks except that bone is added caudal ends of the cartilaginous pterygoquadrate undergo endochondralossification & become the quadrate bones. The remainder becomes thepalatine & pterygoid bones. The posterior tip of Meckel's cartilage becomesan articular bone. (Seehttp://www.usm.maine.edu/bio/courses/bio205/bio205_08_skull_2.html)

Feeding movements in many bony fishes -> cranial kinesis (see Figure 9.23,p.351 of text)

Cranial kinesis:

movement between the upper jaw and braincase advantages:
http://tooldoc.wncc.nevada.edu/figure2.htmhttp://www.biology.eku.edu/ritchiso/342notes3.htm#catskull#catskullhttp://home.houston.rr.com/vnotes/Bones/Palatines.htmlhttp://www.med.uc.edu/embryology/chapter12/animations/ipalate.avihttp://faculty.washington.edu/kepeter/453/photos/skeleton_photos/amia_skeleton1.jpghttp://faculty.washington.edu/kepeter/453/photos/skeleton_photos/amia_skeleton1.jpghttp://www.usm.maine.edu/bio/courses/bio205/bio205_08_skull_2.htmlhttp://www.usm.maine.edu/bio/courses/bio205/bio205_08_skull_2.htmlhttp://www.usm.maine.edu/bio/courses/bio205/bio205_08_skull_2.htmlhttp://www.usm.maine.edu/bio/courses/bio205/bio205_08_skull_2.htmlhttp://faculty.washington.edu/kepeter/453/photos/skeleton_photos/amia_skeleton1.jpghttp://www.med.uc.edu/embryology/chapter12/animations/ipalate.avihttp://home.houston.rr.com/vnotes/Bones/Palatines.htmlhttp://www.biology.eku.edu/ritchiso/342notes3.htm#catskull#catskullhttp://tooldoc.wncc.nevada.edu/figure2.htm


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o provides a way to change the size and configuration of the mouthrapidly

o optimize biting and rapid feeding. disadvantages: lose force, difficult to optimize apposition of occlusive

surfaces.

See also: Shark Jaw Movement

Cyclostomes

visceral skeleton unlike that of jawed fishes Hagfishes - no identifiable pterygoquadrate or Meckel's cartilage

Jaw suspension of fishes

The jaw-hyoid complex of fishes requires bracing against some support tofunction effectively, and the nearest one is the neurocranium(endocranium).

Types of suspensions:o autostyly (below left) - hyomandibula play no role in bracing thejaws (lungfish & tetrapods)o amphistyly (below middle) - jaws & hyomandibula both braced

directly against the braincase (extinct sharks)

o hyostyly (below right) - mandibular cartilage is braced against theotic capsule; jaws braced against hyomandibula (sharks &present-day bony fishes)

Source: http://www.uta.edu/biology/restricted/3452hske.htm

TETRAPODS - With life on land (& pulmonary respiration), the visceral skeletonunderwent substantial modification. Some structures were lost & others remained toperform new functions.

Pterygoquadrate (palatoquadrate) cartilage = embryonic upper jawcartilage

o Amphibians, reptiles, & birds - posterior end undergoesendochondral ossification & becomes the quadrate (whicharticulates with the articular bone of the lower jaw)

Source: http://www-users.york.ac.uk/~wjh101/hedbone/Turtle/turtle.htm

o Mammals - dentary (lower jaw) articulates with the squamosal ofskull (quadrate separates from the rest of the palatoquadrate &becomes the incus of the middle ear)

Meckel's cartilage

o Reptiles - largely ensheathed by dermal bones (as in the aboveturtle)

o Birds & mammals - few or no remnants in adult lower jaw (&, inmammals, the articular, formed by ossification of the tip ofMeckel's cartilage, projects into the middle ear cavity & becomesthe malleus)

Source: http://home.houston.rr.com/vnotes/Bones/Meckel.html

Arch II = Hyomandibular cartilage:o Sharks - interposed between quadrate region & otic capsuleo Tetrapods - no longer articulates with quadrate & ossifies to

become part of the stapes (columella)

Arches III ---> V become part of hyoid apparatus Arches VI & VII - not present in tetrapods

Source: http://www.liberty.edu/academics/registrar/courses00/biol418pa.htm

Hyoid apparatus of tetrapods

consists of a body & 2 or 3 horns (cornua) anchors tongue, provides attachment for some extrinsic muscles of larynx,

& is site of attachment of muscles that aid in swallowing

Lower jaw

may have originated as part of a visceral arch, as in sharks (mandibularcartilage)

in bony vertebrates, mandibular cartilage is reinforced & largely replacedby a series of dermal bones

Skeletal

BIO 342Comparative Vertebrate AnatomyLecture Notes 5 - Skeletal System IVAppendicular Skeleton

Appendicular skeleton

consists of pectoral & pelvic girdles plus skeleton of fins & limbs Some vertebrates have no appendicular skeleton (e.g., agnathans,

apodans, snakes, & some lizards) & in others it is much reduced.
http://science.howstuffworks.com/shark5.htmhttp://www.mun.ca/biology/scarr/Vertebrates_Jaw_Types.htmhttp://www.mun.ca/biology/scarr/Vertebrates_Jaw_Types.htmhttp://science.howstuffworks.com/shark5.htmhttp://www.uta.edu/biology/restricted/3452hske.htmhttp://www-users.york.ac.uk/~wjh101/hedbone/Turtle/turtle.htmhttp://home.houston.rr.com/vnotes/Bones/Meckel.htmlhttp://www.liberty.edu/academics/registrar/courses00/biol418pa.htmhttp://www.biology.eku.edu/ritchiso/342notes2.htmhttp://www.biology.eku.edu/ritchiso/342notes2.htmhttp://www.liberty.edu/academics/registrar/courses00/biol418pa.htmhttp://home.houston.rr.com/vnotes/Bones/Meckel.htmlhttp://www-users.york.ac.uk/~wjh101/hedbone/Turtle/turtle.htmhttp://www.uta.edu/biology/restricted/3452hske.htmhttp://science.howstuffworks.com/shark5.htmhttp://www.mun.ca/biology/scarr/Vertebrates_Jaw_Types.htmhttp://science.howstuffworks.com/shark5.htm


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Pectoral girdles:

1 - brace for anterior appendages

2 - consist of membrane & replacement bones (in bony vertebrates)

3 - Early fishes had 3 replacement bones (coracoid, scapula, & suprascapula) and aseries of dermal bones (clavicle, cleithrum, supracleithrum, and post-temporal)

4 - Later bony fishes (ganoid fish) - tendency for reduction in number and size ofreplacement bones

5 - Tetrapods - tendency for reduction in number of dermal bones

Source: http://www.uta.edu/biology/restricted/3452gird.htm

Bony fishes - pectoral girdles of living bony fishes have reduced coracoid & scapula(replacement bone) but large cleithrum & supracleithrum (dermal bone). Aposttemporal bone (dermal) connects the supracleithrum to the skull.


Cartilaginous fishes - no dermal bone


Tetrapods - early ones had pectoral girdle similar to those of early bony fishes, butlost posttemporal & acquired interclavicle (which still occurs in several amniotes,e.g., alligator, birds, & monotremes)

Clavicle & coracoid - one or both typically brace scapula against sternum (as inbirds; below)

Scapula - present in all tetrapods with even vestiges of anterior limbs, e.g., turtles&birds &mammals

Pelvic girdles

brace posterior paired appendages no dermal components (unlike pectoral girdle)

Fishes - pelvic girdle consists of 2 cartilaginous or bony plates (ischiopubic plates)that articulate with the pelvic fins


Tetrapods - pair of cartilaginous plates form in embryos & each ossifies at 2centers to form: pubis & ischium. An additional blastema gives rise to the ilium.

Frogs & toads

ilia elongated & extend from sacral vertebra to urostyle joint between ilium & sacral vertebra (sacroiliac) is freely moveable (&

moves when a frog or toad jumps)

Birds:

ilium & ischium expanded to accommodate musculature needed for bipedallocomotion

girdle is braced against lumbar & sacral vertebrae pubic bones are typically reduced (long but thin); the limited pubic

symphysis provides a larger outlet for eggs

Mammals - ilium, ischium, and pubis unite to form the innominate bone (the 2innominates = pelvic girdle)

FINS

All jawed fishes (except eels) have pectoral & pelvic fins Fins are used primarily for steering ('rudders') Types of fins:

o lobed fins - found in sarcopterygianso fin fold fins (see diagram below)

found in cartilaginous fish consist of 1 to 5 basal cartilages plus several rows of

radials

o ray fin - tendency to lose proximal components of fin skeleton(see diagram below)
http://www.uta.edu/biology/restricted/3452gird.htmhttp://www.uta.edu/biology/restricted/3452gird.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic9/Topic9.html#chondrichhttp://www.uta.edu/biology/restricted/3452gird.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic9/Topic9.html#tetrapodshttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/turtappenskelamy-becky.htmlhttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/skeleton/girdle6/girdle2.htmlhttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/skeleton/girdle4/girdle1.htmlhttp://www.uta.edu/biology/restricted/3452gird.htmhttp://www2.biology.ualberta.ca/jackson.hp/IWR/Content/Anatomy/Swimming/Information/swim.fishcentric.gifhttp://www2.biology.ualberta.ca/jackson.hp/IWR/Content/Anatomy/Swimming/Information/swim.fishcentric.gifhttp://www.uta.edu/biology/restricted/3452gird.htmhttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/skeleton/girdle4/girdle1.htmlhttp://trc.ucdavis.edu/mjguinan/apc100/modules/Musculoskeletal/skeleton/girdle6/girdle2.htmlhttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/turtappenskelamy-becky.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic9/Topic9.html#tetrapodshttp://www.uta.edu/biology/restricted/3452gird.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic9/Topic9.html#chondrichhttp://www.uta.edu/biology/restricted/3452gird.htmhttp://www.uta.edu/biology/restricted/3452gird.htm


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Limbs

Starting with amphibians, vertebrates typically have 4 limbs. However,some have lost one or both pairs &, in others, one pair is modified as arms,wings, or paddles

typically have 5 segments:o Anterior limb

brachium (upper arm) - consists of humerus antebrachium (forearm) - consists of radius & ulna carpus (wrist) - consists of carpals metacarpus (palm) - consists of metacarpals digits - consist of phalanges

o Posterior limb femur (thigh) - consists of femur crus (shank) - consists of tibia & fibula tarsus (ankle) - consists of tarsals metatarsus (instep) - consists of metatarsals digits - consist of phalanges


Some vertebrates lack both pairs of limbs

caecilians (apodans) most snakes snake-like lizards

Some vertebrates have forelimbs only:

manatees & dugongs dolphins (see diagram below) cetaceans (vestigial elements may be embedded in body wall) sirens (salamander)

Early tetrapods - limbs were short & first segment extended straight out from thebody . This posture persists among lower tetrapods (e.g, see the alligator below),but, in birds & mammals, there has been a rotation of the appendages so that thelong axis of the humerus & femur more nearly parallels the vertebral column.

Arm & forearmo Upper arm = humeruso Forearm = radius & ulnao Manus (or hand)

Wrist - 3 rows of carpal bones: proximal row = radiale, ulnare, intermedium, &

pisiform middle row = 3 central carpals (centralia)

distal row = 5 distal carplas numbered 1 through5 (starting on thumb, or radial, side)

Palm - metacarpals Digits

each consists of a series of phalanges general formula' (starting at thumb) = 2,3,4,5,3

Adaptive modifications of the manus

1 - Flight

Birds - loss of digits & bones plus fusion of some bones Bats - 5 digits; elongated metacarpals (II through V) & phalanges support

the patagium

Pterosaurs - 4th digit elongated to support patagium

2 - Swimming - increase in number, & size, of phalanges

3 - Terrestrial locomotion (walking & running):

Plantigrade flat-footed all bones of manus and/or pes on the ground amphibians, most reptiles (see alligator photo

above), & some mammals (insectivores,monkeys, apes, humans, & bears)

Digitigrade 1st digit is reduced or lost manus & pes are elevated rabbits, rodents, & many carnivores

Unguligrade reduced number of digits walk on tips of remaining digits claws become hooves

As the fastest North American mammal, pronghorn antelope (unguligrades) canreach speeds of 60 miles per hour.

At high speed they cover the ground in strides of 14 to 24 feet, and are known to

run for long distances at speeds of 30 to 40 miles per hour.
http://www.uta.edu/biology/restricted/3452gird.htmhttp://www.whalesafari.no/whalecenter/skeleton.htmlhttp://www.biology.eku.edu/ritchiso/342notes5.htm#dolphin#dolphinhttp://animaldiversity.ummz.umich.edu/anat/running_fast.htmlhttp://animaldiversity.ummz.umich.edu/anat/running_fast.htmlhttp://www.biology.eku.edu/ritchiso/342notes5.htm#dolphin#dolphinhttp://www.whalesafari.no/whalecenter/skeleton.htmlhttp://www.uta.edu/biology/restricted/3452gird.htm


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4 - Grasping

o opposable thumb saddle joint at base of thumb where it meets palm thumb at wider angle from index finger strong thumb muscles

Posterior limbs - bones are comparable to those of forelimbs except that a patella

(kneecap') develops in birds & mammals

Origin of fins:

1 - Fin fold hypothesis - f ins derived from continuous fold of body wall

Ammoecetes

2 - Gill arch hypothesis - fins derived from the last 2 gill arches (very unlikely)

3 - Fin spine hypothesis - fins derived from tissue attached to spines (that may

have evolved to provide protection from predators)

Acanthodiian

Origin of limbs - derived from paired fins of ancient fishes:

Used by permission ofJohn W. Kimble

The first tetrapods, Labyrinthodont amphibians (right), probably evolvedfrom a Crossopterygian ancestor (left).

When the fresh water pools in which these fish lived became stagnant, theymay have crawled up the bank to breath air using

primitive lungs. As the lobed fins of these fish evolved into stronger limbs,the first tetrapods appeared.

rison of paired anterior fins ofned fishes (A-D) and limbs of

trapods (E, F)

opterygion, B. Sauripterus,erichthys, D. Eusthenopteron,

E. Ichthyostega, F. Acanthostega

Here we have a possible explanation forthe formation of a new morphological

feature - limbs with digits - from thepaired fins of sarcopterygian (lobefinned) fishes. Some of these fish

(notably Eusthenopteron) have bones intheir paired fins that are very similar tothe bones of tetrapod limbs.

Specifically, they have a single bone(similar to the humerus or femur)followed by paired bones (similar to the

radius and ulna or fibula and tibia of

tetrapods). Scientists thinkEusthenopterons used their limbs towalk on the sea (or lake or river) bed.

What Eusthenopteron lacks are digits -having fin rays instead (although

Sauripterus is a closely related fish thatdoes have 8 digits just like the earliestamphibians - see the illustration).

However, the fossil record supplies uswith examples of tetrapods that arequite similar to Eusthenopteron -

Acanthostega and Icthyostega.

BIO 342Comparative Vertebrate AnatomyLecture Notes 6 - Muscular System

Vertebrate muscles:

striated vs. smooth voluntary vs. involuntary skeletal vs. non-skeletal

Skeletal muscle (left) & Smooth muscle (right)

Skeletal muscle = muscles attached to the skeleton that are striated & voluntary

Non-skeletal muscle = muscles not attached to the skeleton; most are smooth &involuntary

Vertebrate Muscles:

1 - Skeletal, striated, voluntary muscles
http://www.bbc.co.uk/science/humanbody/body/factfiles/joints/saddle_joint.shtmlhttp://www.arthroscopy.com/sp05001.htmhttp://www.ultranet.com/~jkimball/BiologyPages/V/Vertebrates.htmlhttp://www.arthroscopy.com/sp05001.htmhttp://www.arthroscopy.com/sp05001.htmhttp://www.bbc.co.uk/science/humanbody/body/factfiles/muscle_anatomy.shtmlhttp://www.bbc.co.uk/science/humanbody/body/factfiles/muscle_anatomy.shtmlhttp://www.ultranet.com/~jkimball/BiologyPages/V/Vertebrates.htmlhttp://www.arthroscopy.com/sp05001.htmhttp://www.bbc.co.uk/science/humanbody/body/factfiles/joints/saddle_joint.shtml


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o axial body wall & tail hypobranchial & tongue extrinsic eyeball muscles

o appendicularo branchiomeric (homologous to the branchial/ pharyngeal muscles

from fishes to mammals, striated muscles, innervated by cranialnerves)

o integumentary2 - Non-skeletal, smooth, chiefly involuntary muscles

o muscles of tubes, vessels, &hollow organso intrinsic eyeball muscleso erectors of feathers & hair

3 - Cardiac muscle

4 - Electric organs

Skeletal muscles have muscular & tendinous portions:

Muscle - consists of skeletal muscle cells (which, in turn, consist ofmyofibrils and myofilaments)

Tendons - extensions of a muscle's tough connective tissue sheath (fascia& epimysium) that anchor a muscle to its origin & insertion

o Origin = site of attachment that is relatively fixedo Insertion = site of attachment that is normally displaced by

contraction of the muscle

Used with permission ofJohn W. Kimball

Names of skeletal muscles are based on:

direction of fibers (e.g., oblique) location or position (e.g., superficial) number of divisions (e.g., triceps) shape (e.g., deltoid) origin and/or insertion (e.g., iliocostalis) action (e.g., levator scapulae) size (e.g., major) or some combination of these

Homologies:

Human muscles were named several hundred years ago, & many of these namesare still used. Based on similarities of origins & insertions, these names weresubsequently used for the, apparently, corresponding muscles of other vertebrates.However, origins & insertions are not reliable criteria for determining homologybecause natural selection has sometimes favored 'shifts' in muscle position. Morereliable criteria for determining homologies are:

o embryonic origino nerve supply

Source: http://www.ucalgary.ca/UofC/eduweb/virtualembryo/why_fish.html

Axial Muscles:

include the skeletal muscles of the trunk & tail extend forward beneath the pharynx as hypobranchial muscles &muscles

of the tongue

are present in orbits as extrinsic eyeball muscles (check slide 27 in thispowerpoint presentation)

are metameric (most evident in fish and aquatic amphibians where theaxial muscles are used in locomotion; in other tetrapods, metamerism is

obscured due to presence of paired appendages responsible for locomotionon land)

are segmental because of their embryonic origin; arise from segmentalmesodermal somites

Source: http://www.uta.edu/biology/restricted/3452mus.htm

Axial musculature of an aquatic salamander, Necturus maculosus. The layers oflateral hypaxial musculature are exposed from superficial to deep in the cranial to

caudal direction. The number of external oblique layers varies between one and twoin this species (the f igured specimen exhibits two). Abbreviations: oes, M. obliquus

externus superficialis; oep, M. obliquus externus profundus; oi, M. obliquusinternus; ta, M. transversus abdominis (Brainerd and Simons 2000).

Trunk & tail muscles of fish:

Axial musculature consists of a series of segments (myomeres) separated bymyosepta

o Myosepta serve as origins & insertions for segmented muscleso Myomeres are divided into dorsal & ventral masses by a horizontal

septum that extends between the transverse processes of thevertebrae:

Epaxials = above the septum Hypaxials = below the septum
http://www.wa-eyemd.org/anatomy-muscles.htmhttp://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/stomach_peristalsis.shtmlhttp://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.htmlhttp://www.ultranet.com/~jkimball/BiologyPages/M/Muscles.htmlhttp://www.exrx.net/Muscles/Obliques.htmlhttp://www.exrx.net/Muscles/WristFlexors.htmlhttp://www.exrx.net/Muscles/TricepsBrachii.htmlhttp://www.exrx.net/Muscles/DeltoidAnterior.htmlhttp://www.deeptissue.com/learn/torso/iliocost.htmhttp://www.exrx.net/Muscles/LevatorScapulae.htmlhttp://www.exrx.net/Muscles/TeresMajor.htmlhttp://www.ucalgary.ca/UofC/eduweb/virtualembryo/why_fish.htmlhttp://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter11/medialib/CH11/html/ch11_4_1.htmlhttp://www.vh.org/adult/provider/anatomy/atlasofanatomy/plate32/05inftongue.htmlhttp://www.vh.org/adult/provider/anatomy/atlasofanatomy/plate32/05inftongue.htmlhttp://www.blinn.edu/brazos/natscience/jrugila/chapt15-01.ppthttp://www.blinn.edu/brazos/natscience/jrugila/chapt15-01.ppthttp://www.uta.edu/biology/restricted/3452mus.htmhttp://www2.biology.ualberta.ca/jackson.hp/IWR/Content/Anatomy/Swimming/Information/swim.fishcentric.gifhttp://www.zod.wau.nl/ezo/Research/WebPageJohan1.htmhttp://www.zod.wau.nl/ezo/Research/WebPageJohan1.htmhttp://www2.biology.ualberta.ca/jackson.hp/IWR/Content/Anatomy/Swimming/Information/swim.fishcentric.gifhttp://www.uta.edu/biology/restricted/3452mus.htmhttp://www.blinn.edu/brazos/natscience/jrugila/chapt15-01.ppthttp://www.blinn.edu/brazos/natscience/jrugila/chapt15-01.ppthttp://www.vh.org/adult/provider/anatomy/atlasofanatomy/plate32/05inftongue.htmlhttp://www.vh.org/adult/provider/anatomy/atlasofanatomy/plate32/05inftongue.htmlhttp://cwx.prenhall.com/bookbind/pubbooks/martinidemo/chapter11/medialib/CH11/html/ch11_4_1.htmlhttp://www.ucalgary.ca/UofC/eduweb/virtualembryo/why_fish.htmlhttp://www.exrx.net/Muscles/TeresMajor.htmlhttp://www.exrx.net/Muscles/LevatorScapulae.htmlhttp://www.deeptissue.com/learn/torso/iliocost.htmhttp://www.exrx.net/Muscles/DeltoidAnterior.htmlhttp://www.exrx.net/Muscles/TricepsBrachii.htmlhttp://www.exrx.net/Muscles/WristFlexors.htmlhttp://www.exrx.net/Muscles/Obliques.htmlhttp://www.ultranet.com/~jkimball/BiologyPages/M/Muscles.htmlhttp://animaldiversity.ummz.umich.edu/site/topics/mammal_anatomy/hair.htmlhttp://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/stomach_peristalsis.shtmlhttp://www.wa-eyemd.org/anatomy-muscles.htm


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o Middorsal & midventral septa separate the myomeres of the 2sides of the body. The midventral septum is called the LINEAALBA.

Trunk & tail muscles of tetrapods

Tetrapods, like fish, have epaxial & hypaxial masses, & these retain someevidence of metamerism even in the highest tetrapods.

Modifications:1 - epaxials are elongated bundles that extend through many body segments & thatare located below the expanded appendicular muscles required to operate the limbs

2 - hypaxials of the abdomen have no myosepta & form broad sheets of muscle

3 - hypaxials are oriented into oblique, rectus, & transverse bundles

Epaxials of tetrapods:

lie along vertebral column dorsal to transverse processes & lateral toneural arches

extend from base of the skull to tip of the tailo Urodeles & some lizards - epaxials are obviously metameric & are

referred to as the dorsalis trunci (see salamander above)

o Higher tetrapods - superficial epaxial bundles form long musclesthat extend over many body segments; deep bundles are stillsegmented

Longest bundles:

1- longissimus group

lies on transverse processes ofvertebrae; includes the longest epaxialbundles

subdivisions include: longissimus dorsi longissimus cervicis longissimus capitis

2 - iliocostalis group

lateral to longissimus & spinalis arises on ilium & inserts on dorsal ends

of ribs or uncinate processes

3 - spinalis group

lies close to neural arches connects spinous processes or

transverse processes with those severalvertebrae anteriorly

Shortest bundles - intervertebrals

remain segmented connect processes (spinous, transverse, &

zygapophyses) of adjacent vertebrae

Hypaxials of tetrapods:

1 - Muscles of lateral body wall:

o oblique (external & internal), transverse, & rectus muscles2 - Muscles that form longitudinal bands in roof of body cavity (subvertebralmuscles)

Oblique & transverse muscles:

Early amphibians & reptileso ribs developed in myosepta along entire length of the trunko urodeles still have myosepta the length of the trunk, but ribs no

longer form in all of them

Modern amnioteso myosepta & ribs are restricted to the thorax (so abdominal

muscles are not obviously segmented)

o hypaxials form 3 layers: external oblique, internal oblique, &transverse (in the thorax region: external & internal intercostals,which play an important role in respiration, & transverse muscle)

1 - External intercostal muscles, 2 - Internal intercostal muscles, 3 - Ribs, 4 -Intercartilaginous muscles,

5 - Sternum, 6 - Subcostal muscles, & 7 - Vertebral columnSource: http://www.sci.port.ac.uk/rad/anatomy/07/006.htm

Rectus muscles:

weakly developed in most fish; 'stronger' in tetrapods support ventral body wall & aid in arching the back in mammals - rectus abdominis (typically extends from the anterior end of

the sternum to the pelvic girdle)

Subvertebral muscles:
http://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.sci.port.ac.uk/rad/anatomy/07/006.htmhttp://www.sci.port.ac.uk/rad/anatomy/07/006.htmhttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeghttp://www.bio.davidson.edu/people/jeputnam/companat/restricted/CA3_Mu_2BackMusEvol.jpeg


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underneath & against transverse processes of vertebrae includes the psoas & iliacus in the lumbar region & the longus colli in the

neck

less developed in the thorax & none in the tail

FUNCTION OF EPAXIALS OF TETRAPODS:

1 - short epaxials perform same function as in fish (side-to-side movements of

vertebral column)

2 - short & long bundles arch & support the vertebral column

3 - most anterior bundles = attach to & move the skull

FUNCTION OF HYPAXIALS OF TETRAPODS:

1 - Aquatic urodeles = used chiefly for swimming

Diagram showing the onset and duration of lateral hypaxial muscle EMG activityrelative to maximum body bending in twoAmbystoma tigrinum during swimming.Values are means S.D. for alpha-burst (filled bars) and beta-burst (open bars)

onset and duration times. OES, m. obliquus externus superficialis; OEP, m. obliquusexternus profundus; OI, m. obliquus internus; TA, m. transversus abdominis.

*Denotes the side of the body on which the electrodes were implanted (Bennett etal. 2001).

2 - Terrestrial urodeles = assist in locomotion

3 - Other tetrapods = reduced in volume compared to fish (because of shift in modeof locomotion); now support contents of abdomen, assist in respiration (especiallyintercostal muscles), & assist epaxials in bending vertebral column (rectus muscles)

Hypobranchial & tongue muscles:

Fisho hypobranchials extend forward from pectoral girdle & insert on

mandible, hyoid, & gill cartilages

o hypobranchials strengthen floor of pharynx & assist branchiomericmuscles in elevating floor of mouth, lowering jaw, & extending gillpouches

Tetrapodso hypobranchials stabilize &move hyoid apparatus & larynx

o the tongue of amniotes is a 'sac' anchored to hyoid skeleton &filled with hypobranchial muscle

The neck muscles ending in "hyoid" are associated with the hyoid apparatus,whereas those

beginning or ending with "thyro" are attached to the larynx. These muscles arehypobranchia

and function in movement of the hyoid apparatus, larynx and/or floor of the mouth.

Appendicular muscles - move fins or limbs

Extrinsic - originate on axial skeleton or fascia or trunk & insert on girdlesor limbs

Intrinsic - originate on girdle or proximal skeletal elements of appendage &insert on more distal elements

Fish - appendicular muscles serve mostly as stabilizers; intrinsic muscles arelimited in number & undifferentiated

Tetrapods - appendicular muscles are much more complicated than in fish

o greater leverage required for locomotion on lando jointed appendages (as opposed to fins) require complex muscles

Extrinsic appendicular musculature

Dorsal group of the forelimbs, e.g., trapezius and latissimus dorsi, arise on:1 - fascia of trunk in lower tetrapods

2 - skull, vertebral column, & ribs to a point well behind the scapula in higher

tetrapods & converge

on the girdle & limb

Ventral group, e.g., pectoralis, arises on sternum & coracoid, & convergeon limb

RESULT = pectoral girdle & limb are joined to trunk by extrinsic appendicularmuscles as illustrated in this diagram:

The 'muscular sling' of tetrapods. Appendicular muscles of the forelimbs suspend

the anterior body of tetrapods from the shoulders. Some of these muscles are axial
http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/psmj.htmhttp://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/ilia.htmhttp://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/lncl.htmhttp://birg.epfl.ch/page28707.htmlhttp://members.tripod.lycos.co.kr/Shiranami/html/mResp.htmlhttp://digimorph.org/specimens/Chamaeleo_calyptratus/whole/http://www.uia.ac.be/u/aherrel/chameleon.htmlhttp://www.uia.ac.be/u/aherrel/chameleon.htmlhttp://digimorph.org/specimens/Chamaeleo_calyptratus/whole/http://members.tripod.lycos.co.kr/Shiranami/html/mResp.htmlhttp://birg.epfl.ch/page28707.htmlhttp://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/lncl.htmhttp://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/ilia.htmhttp://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/psmj.htm


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muscles (rhomboideus & serratus ventralis), some are branchial muscles(trapezius), & some arise from the forelimb musculature itself (pectoralis).

The pelvic girdle requires no such muscular anchoring because it is attached directlyto the vertebral column. As a result, the volume of extrinsic muscle is relativelysmall in posterior limbs.

Extrinsic appendicular muscles:

1 - most develop from hypaxial blastemas in the body wall

2 - referred to as secondary appendicular muscles because it was not their originalfunction to operate appendages

3 - chief extrinsic muscles of forelimbs of tetrapods include: scapular deltoid,latissimus dorsi, rhomboideus, serratus ventralis, & pectorals

Intrinsic appendicular muscles:

1 - form from blastemas within the limb bud

2 - called primary appendicular muscles

Appendicular muscles:

Amphibians - much more complex than in fish

Reptiles - more numerous & diverse than in amphibians; better support of body &increased mobility of distal segments of the limbs

Birds - intrinsic musculature is reduced; pectoralis (downstroke muscle) &supracoracoideus (upstroke muscle) are enlarged

Mammals - similar to reptiles but more diverse

Branchiomeric muscles:

1 - associated with the pharyngeal arches

2 - series of skeletal & smooth muscles

3 - adductors, constrictors, & levators operate jaws plus successive gill arches

Muscles of the Mandibular Arch:

o Squalus & other fish - operate the jaws (adductor mandibulae &intermandibularis)

o Tetrapods muscles of 1st arch still operate jaws adductors of mandible:

masseter & temporalis (see diagram below) pterygoid digastric

Muscles of the Hyoid Arch:

o move hyoid archo aid in hearing (stapedial muscle)o assist in moving lower jaw (e.g., digastric)

Muscles of 3rd & successive arches:

o Squalus - constrictors above & below gill chambers plus levators(including the cucullaris) that compress & expand the gill pouches

o Bony fish - muscles reduced; operculum plays important role inrespiration

o Tetrapods - muscles further reduced; primary muscles include: stylopharyngeus (Arch III) - used for swallowing intrinsic muscles of the larynx or 'voicebox' (remaining

arches)

cucullaris - gives rise to trapezius, cleidomastoid, &sternocleidomastoid muscles of amniotes

Integumentary muscles:

Extrinsic integumentary muscles (e.g., platysma)

o originate (usually) on the skeleton & insert on the underside of thedermis

o striatedo move skin of amniotes

Intrinsic integumentary muscles (arrector pili muscles)

o entirely within the dermiso found in birds & mammalso mostly smooth muscles

Electric organs:

1 - consist of a number of electric discs (up to 20,000) piled in either vertical orhorizontal columns
http://www.ebi.calpoly.edu/BioSci/Courses/BIO/CompAnat/Necturus/NecturusDorsal1.htmlhttp://www.ebi.calpoly.edu/BioSci/Courses/BIO/CompAnat/Necturus/NecturusDorsal1.html


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2 - each disc (electroplax) is a large coin-shaped cell

3 - evolved several times in a variety offish (good example of convergentevolution)

Several species of fish have evolved an electric organ in their tail that produces acontinous electric signal

that propogates through the water. These fish have specialized receptors on theirskin surface that can "feel" electricity.Objects in their environment, such as rocks, plants and pirhanas disturb the flow of

their electric signal through the water.This disturbance will affect how strong the electric field is on a patch of skin near

the object. In other words, a non-conductiveobject such as a rock will cast an electric "shadow" on the skin. The skin receptors

near the object sense these disturbancesand then increase or decrease their signal rate (depending wether the local electric

field increased or decreased in intensity). Thesesignals are then sent up to specialized regions of the brain that collate all the

information and compute a coherent "picture" of thefish's environment (see http://soma.npa.uiuc.edu/labs/nelson/electrolocation.html).

Functions of electric organs:

1 - defense

2 - communication

3 - locating prey (electrolocation)

BIO 342Comparative Vertebrate AnatomyLecture Notes 7 - Digestive System

Digestive tract -tube from mouth to vent or anus that functions in:

ingestion digestion absorption egestion

Major subdivisions include the oral cavity, pharynx, esophagus, stomach, small &large intestines, and cloaca. Accessory organs include the tongue, teeth, oralglands, pancreas, liver, & gall bladder.

Differences in the anatomy of vertebrate digestive tracts is often correlated withthe nature & abundance of food:

readily absorbed (e.g., hummingbirds) vs. requiring extensive enzymaticactivity (e.g., carnivores)

constant food supply (e.g., herbivores) vs. scattered supply (e.g.,carnivores)

The embryonic digestive tract of vertebrates consists of 3 regions:

1 - midgut - contains yolk or attached yolk sac

2 - foregut - oral cavity, pharynx, esophagus, stomach, & smallintestine

3 - hindgut - large intestine & cloaca

Mouth & oral cavity. The oral cavity begins at the mouth & ends at the pharynx.Fish have a very short oral cavity, while tetrapods typically have longer oralcavities. The mammalian mouth is specialized to serve as a suckling andmasticatory organ (with muscular cheeks).

Palate = roof of the oral cavityo primary palate - internal nares lead into the oral cavity anteriorlyo secondary palate - nasal passages are located above the

secondary palate and open at the end of the oral cavity

Teeth are derivations of dermal armor.

Placoid scales - show gradual transition to teeth at the edge of the jaw Composition of teeth - primarily dentin surrounded by enamel Vary among vertebrates in number, distribution in the oral cavity, degree

of permanence, mode of attachment, & shape

Toothless vertebrates are found in every class of vertebrates and includeagnathans, sturgeons, some toads, turtles, birds, &baleen whales.

A right whale swims at or near the surface of the water with its mouth open.Water and food enter through a gap in the front baleen plates, and

food is caught in the matted baleen fringes inside.

Toothed vertebrates:

Fish - teeth are numerous & widely distributed in the oral cavity & pharynx Early tetrapods - teeth widely distributed on the palate; most amphibians &

some reptiles still have teeth on the vomer, palatine, & pterygoid bones

Crocodilians, toothed birds, & mammals - teeth are limited to the jaws
http://soma.npa.uiuc.edu/labs/nelson/electric_fish.htmlhttp://soma.npa.uiuc.edu/labs/nelson/electrolocation.htmlhttp://soma.npa.uiuc.edu/labs/nelson/electrolocation.htmlhttp://www.whalecenter.org/album/album27.htmhttp://www.meer.org/general-fish-teeth-gills.htmhttp://www.meer.org/general-fish-teeth-gills.htmhttp://www.whalecenter.org/album/album27.htmhttp://soma.npa.uiuc.edu/labs/nelson/electrolocation.htmlhttp://soma.npa.uiuc.edu/labs/nelson/electrolocation.htmlhttp://soma.npa.uiuc.edu/labs/nelson/electric_fish.html


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TEETH:

1 - have tended toward reduced numbers & distribution

2 - most vertebrates (through reptiles) have succession of teeth

3 - most vertebrates (except mammals) replace teeth in waves (back to front;every other tooth)

4 - mammals generally develop 2 sets of teeth: milk (deciduous) teeth &permanent teeth

Morphological variation in teeth:

vertebrates other than mammals - all teeth are shaped alike (homodontdentition)

mammals - teeth exhibit morphological variation: incisors, canines,premolars, & molars (heterodont dentition)

o incisors = cuttingo canines = piercing & tearingo premolars & molars = macerating

Tongue:

Gnathostome fish & primitive amphibians - tongue is a simple crescent-shaped elevation in the floor of the oral cavity caused by the underlyinghyoid skeleton & is called the primary tongue

Most amphibians - primary tongue (or hypobranchial eminence) +glandular field (or tuberculum impar) ('stuffed' with hypobranchialmusculature)

Reptiles & mammals - primary tongue + glandular field (or tuberculumimpar) + lateral lingual swellings (more hypobranchial muscle)

Birds - lateral lingual swellings are suppressed & intrinsic muscle is usuallylacking

Tongue mobility:

Turtles, crocodilians, some birds, & whales - tongue is largely immobilizedin the floor of the oral cavity & cannot be extended

Snakes, insectivorous lizards &amphibians, & some birds - tonguesometimes long and may move in and out of the oral cavity(seehttp://www.autodax.net/feedingmovieindex.html)

Mammals - tongue is attached to the floor of the oral cavity (via thefrenulum) but can still be extended out of the oral cavity

Using a keen sense of smell, anteaters are able to effectively track downant nests on the forest floor. Once a nest is found, the mammal usually rips it open

with its sharp foreclaws to expose its delectable contents. The anteater thenproceeds to

catch and eat the ants by repetitively flicking its long sticky tongue in and out of thenest.

The giant anteater's unique tongue can measure as long as two feet (60 cm).

Functions of vertebrate tongues:

capturing & gathering food (see woodpecker tongue below) taste manipulate fluids & solids in oral cavity swallowing thermoregulation grooming human speech

Oral glands - secrete a variety of substances including:

salivao Lubrication and binding: the mucus in saliva is extremely effective

in binding masticated food into a slippery bolus that (usually)slides easily through the esophagus without inflicting damage tothe mucosa. Saliva also coats the oral cavity and esophagus, andfood basically never directly touches the epithelial cells of thosetissues.

o Solubilizes dry food: in order to be tasted (by taste buds), themolecules in food must be solubilized.

o Oral hygiene: The oral cavity is almost constantly flushed withsaliva, which floats away food debris and keeps the mouthrelatively clean. Saliva also contains lysozyme, an enzyme thatlyses many bacteria and prevents overgrowth of oral microbial

populations.o Initiates starch digestion: in most species, amylase is present in

saliva and begins to digest dietary starch into maltose. Amylasedoes not occur in the saliva of carnivores.

o Provides alkaline buffering and fluid: this is of great importance inruminants, which have non-secretory forestomachs.

o Evaporative cooling: clearly of importance in dogs, which havevery poorly developed sweat glands - look at a dog panting after along run and this function will be clear.

poison (lizards, snakes, and mammals) anticoagulant (vampire bats; video)

Pharynx - part of digestive tract exhibiting pharyngeal pouches (at least in theembryo) that may give rise to slits
http://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/%21amis18.htmhttp://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/%21amis18.htmhttp://www-biol.paisley.ac.uk/courses/Tatner/biomedia/pictures/frogf.htmhttp://www.autodax.net/feedingmovieindex.htmlhttp://www.arkive.org/species/GES/mammals/Myrmecophaga_tridactyla/Myrmecophaga_tridactyla_08.html?movietype=qtSmallhttp://www.nature.com/nature/journal/v413/n6852/fig_tab/413219a0_F1.htmlhttp://www.fusion.com.au/tds/http://www.nhm.org/research/mammals/jj/http://www2.ncsu.edu/unity/lockers/project/biovideos/shortclips/Mammals.htmlhttp://wc.pima.edu/Bfiero/tucsonecology/animals/rept_gimo.htmhttp://reptilis.net/serpentes/venom.htmlhttp://pubs.acs.org/cen/critter/8242shrews.htmlhttp://www.pitt.edu/AFShome/s/l/slavic/public/html/courses/vampires/images/bats/vambat.htmlhttp://www.nationalgeographic.com/kids/creature_feature/0110/vampirebats.htmlhttp://www.nationalgeographic.com/kids/creature_feature/0110/vampirebats.htmlhttp://www.pitt.edu/AFShome/s/l/slavic/public/html/courses/vampires/images/bats/vambat.htmlhttp://pubs.acs.org/cen/critter/8242shrews.htmlhttp://reptilis.net/serpentes/venom.htmlhttp://wc.pima.edu/Bfiero/tucsonecology/animals/rept_gimo.htmhttp://www2.ncsu.edu/unity/lockers/project/biovideos/shortclips/Mammals.htmlhttp://www.nhm.org/research/mammals/jj/http://www.fusion.com.au/tds/http://www.nature.com/nature/journal/v413/n6852/fig_tab/413219a0_F1.htmlhttp://www.arkive.org/species/GES/mammals/Myrmecophaga_tridactyla/Myrmecophaga_tridactyla_08.html?movietype=qtSmallhttp://www.autodax.net/feedingmovieindex.htmlhttp://www-biol.paisley.ac.uk/courses/Tatner/biomedia/pictures/frogf.htmhttp://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/%21amis18.htmhttp://www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/%21amis18.htm


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Fish - pharynx is respiratory organ Tetrapods:

o pharynx is the part of the foregut preceeding the esophagus &includes:

glottis (slit leading into the larynx) openings of auditory (eustachian) tubes opening into esophagus

Mammals - an epiglottis is positioned over the glottis so that, when a mammal

swallows, the larynx is drawn forward against the epiglottis & the epiglottis blocksthe glottis (which prevents food or liquids from entering the trachea)

Source: http://www.stroke.cwc.net/niweb/faq.htm

Esophagus:

a distensible muscular tube connecting the pharynx & the stomach may have diverticulum called the crop (see diagram of pigeon below)

Stomach = muscular chamber(s) at end of esophagus

serves as storage & macerating site for ingested solids & secretes digestiveenzymes

Vertebrate stomachs:o Cyclostomes - weakly developed; similar to esophaguso Fish, amphibians, & reptiles - increasing specialization (more

differentiated from the esophagus)

o Birds - proventriculus (glandular stomach) and ventriculus(muscular stomach, or gizzard)

o Mammals - well-developed stomach; ruminants havemultichambered stomachs:

/www.uta.edu/biology/restricted/3452dig.htmReticulo-rumen (reticulum and rumen)

Reticulum and rumen are often discussed together since each compartment is

separated by a low partition. Eighty percent of the capacity of the stomach isrelated to the reticulo-rumen. The contents of the reticulum and rumen intermixfreely. The rumen is the main fermentation vat where billions of microorganisms

attack and break down the relatively indigestible feed components of theruminant's diet.

Omasum

After fermentation in the reticulum and rumen, food passes to the omasum. The

omasum acts as a filter pump to sort liquid and fine food particles. Coarse fibreparticles are not allowed to enter the omasum. Also, the omasum may be the site

for absorption of water, minerals and nitrogen.

Abomasum

The abomasum is the true stomach and the only site on the digestive tproduces gastric juices (HCl and the enzymes, pepsin and rennin). Ing

remains here for 1 to 2 hours.

The intestine is located between the stomach & the cloaca or anus & is an

important site for digestion & absorption. Vertebrate intestines are differentiated tovarying degrees into small & large intestines.

Fishes - relatively straight & short intestine in cartilaginous fishes & in primitivebony fishes (lungfish & sturgeon). However, the intestine of cartilaginous fishes hasa spiral valve.

Amphibians - intestines differentiated into coiled small intestine and short,straight large intestine

Reptiles & Birds - coiled small intestines & a relatively short large intestine (thatempties into the cloaca)

Mammals - small intestine long & coiled and differentiated into duodenum,jejunum, & ileum. The large intestine is often relatively long (but not as long as thesmall intestine). A cecum is often present at the junction of the small & largeintestines in herbivores.

Source: http://www.uta.edu/biology/restricted/3452dig.htm

Accessory organs - Liver, gall bladder, & pancreas

Liver & gall bladdero liver produces bile which is stored in the gall bladder

(cyclostomes, most birds, and some mammals, including cervids,have no gall bladder)

o bile aids in digestion by emulsifying fats (breaking fats down intotiny particles that permits more efficient digestion by enzymes)

Pancreas - secretes pancreatic juice (bicarbonate solution to neutralizeacids coming from the stomach plus enzymes to help digest carbohydrates,fats, and proteins) into the intestine
http://www.stroke.cwc.net/niweb/faq.htmhttp://www.westga.edu/~lkral/peristalsis/index.htmlhttp://www.uwinnipeg.ca/~simmons/fish8.htmhttp://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/stomach_peristalsis.shtmlhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumination.htmlhttp://www.uta.edu/biology/restricted/3452dig.htmhttp://staff.francisparker.org/DJohnson/new%20stuff%20htm/physiology/animations/digestionsmall%20intestine.ramhttp://www.uta.edu/biology/restricted/3452dig.htmhttp://www.uta.edu/biology/restricted/3452dig.htmhttp://staff.francisparker.org/DJohnson/new%20stuff%20htm/physiology/animations/digestionsmall%20intestine.ramhttp://www.uta.edu/biology/restricted/3452dig.htmhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumination.htmlhttp://www.bbc.co.uk/science/humanbody/body/factfiles/skeletalsmoothandcardiac/stomach_peristalsis.shtmlhttp://www.uwinnipeg.ca/~simmons/fish8.htmhttp://www.westga.edu/~lkral/peristalsis/index.htmlhttp://www.stroke.cwc.net/niweb/faq.htm


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Ceca - blind diverticula that serve to increase the surface area of the vertebratedigestive tract

Fishes - pyloric & duodenal ceca are common in teleosts; these are primaryareas for digestion and absorption (not fermentation chambers)

Tetrapods - ceca are present in some herbivores; may contain bacteria thataid in the digestion of cellulose

Source: http://ourworld.compuserve.com/homepages/gr_frank/dig_anat.htm

Cloaca:

chamber at end of digestive tract that receives the intestine, & urinary &genital ducts, & opens to the exterior via the vent

shallow or non-existent in lampreys, ray-finned fishes, & mammals (exceptmonotremes)

if no cloaca is present, the intestine opens directly to the exterior via anus

Source: http://trc.ucdavis.edu/mjguinan/apc100/modules/Reproductive/

BIO 342Comparative Vertebrate AnatomyLecture Notes - Respiratory System

Respiration is the process of obtaining oxygen from the external environment &eliminating CO2.

External respiration - oxygen and carbon dioxide exchanged between theexternal environment & the body cells

Internal respiration - cells use oxygen for ATP production (& producecarbon dioxide in the process)

Adaptations for external respiration:

1 - Primary organs in adult vertebrates are external & internal gills, swimbladders or lungs, skin, & the buccopharyngeal mucosa

2 - Less common respiratory devices include filamentous outgrowths of theposterior trunk & thigh (African hairy frog), lining of the cloaca, & lining ofesophagus

Respiratory organs:

Cutaneous respiration

o respiration through the skin can take place in air, water, or botho most important among amphibians (especially the family

Plethodontidae)

Gills (see Respiration in Fishes)o Cartilaginous fishes:

5 naked gill slits Anterior & posterior walls of the 1st 4 gill chambers have

a gill surface (demibranch). Posterior wall of last (5th)chamber has no demibranch.

Interbranchial septum lies between 2 demibranchs of agill arch

Gill rakers protrude from gill cartilage & guard entranceinto gill chamber

2 demibranchs + septum & associated cartilage, bloodvessels, muscles, & nerves = holobranch

o Bony fishes (teleosts): (See 'Ventilation in Teleost Fishes') usually have 5 gill slits operculum projects backward over gill chambers interbranchial septa are very short or absent

o Agnathans: 6 - 15 pairs of gill pouches pouches connected to pharynx by afferent branchial (or

gill) ducts & to exterior by efferent branchial (or gill)ducts

Larval gills:o External gills

outgrowths from the external surface of 1 or more gillarches

found in lungfish & amphibianso Filamentous extensions of internal gills

project through gill slits occur in early stages of development of elasmobranchs

o Internal gills - hidden behind larval operculum of late anurantadpoles

Swim bladder & origin of lungs - most vertebrates develop an outpocketing ofpharynx or esophagus that becomes one or a pair of sacs (swim bladders or lungs)filled with gases derived directly or indirectly from the atmosphere. Similaritiesbetween swim bladders & lungs indicate they are the same organs.

Vertebrates without swim bladders or lungs include cyclostomes, cartilaginous fish,and a few teleosts (e.g., flounders and other bottom-dwellers).

Swim bladders:

may be paired or unpaired (see diagram above)
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have, during development, a pneumatic duct that usually connects to theesophagus. The duct remains open (physostomous) in bowfins andlungfish, but closes off (physoclistous) in most teleosts.

serve primarily as a hydrostatic organ (regulating a fish's specific gravity) gain gas by way of a 'red body' (or red gland); gas is resorbed via the oval

body on posterior part of bladder

may also play important roles in:o hearing - some freshwater teleosts (e.g., catfish, goldfish, & carp)

'hear' by way of pressure waves transmitted via the swim bladderand small bones called Weberian ossicles (see diagram below)

o sound production - muscles attached to the swim bladder contractto move air between 'sub-chambers' of the bladder. The resultingvibration creates sound in fish such as croakers, grunters, &midshipman fish.

o respiration - the swim bladder of lungfish has number subdivisionsor septa (to increase surface area) & oxygen and carbon dioxide isexchanged between the bladder & the blood

Source: http://www.notcatfish.com/ichthyology/weberian_apperatus.htm

Lungs & associated structures

Larynxo Tetrapods besides mammals - 2 pair of cartilages: artytenoid &

cricoid

o Mammals - paired arytenoids + cricoid + thyroid + several othersmall cartilages including the epiglottis (closes glottis whenswallowing)

o Amphibians, some lizards, & most mammals - also have vocalcords stretched across the laryngeal chamber

Source: http://www.worldzone.net/music/singingvoice/images/glottis.gif

Trachea & syrinxo Trachea

usually about as long as a vertebrates neck (except in afew birds such as cranes)

reinforced by cartilaginous rings (or c-rings) splits into 2 primary bronchi &, in birds only, forms the

syrinx at that point

Lungso Amphibian lungs

2 simple sacs internal lining may be smooth or have simple

sacculations or pockets air exchanged via positive-pressure ventilation

o Reptilian lungs simple sacs in Sphenodon & snakes Lizards, crocodilians, &turtles - lining is septate, with lots

of chambers & subchambers

air exchanged via positive-pressure ventilationo Avian lungs - modified from those of reptiles:

air sacs (diverticula of lungs) extensively distributedthroughout most of the body

arrangement of air ducts in lungs ----> no passageway isa dead-end

air flow through lungs (parabronchi) is unidirectionalo Mammalian lungs:

multichambered & usually divided into lobes air flow is bidirectional:

Trachea primary bronchi secondary bronchi tertiary bronchi bronchioles alveoli

air exchanged via negative pressure ventilation, withpressures changing due to contraction & relaxation of

diaphragm & intercostal muscles

BIO 342Comparative Vertebrate AnatomyLecture Notes 9 - Circulatory System

Vertebrate Circulatory Systems:

transport gases, nutrients, waste products, hormones, heat, & variousother materials

consist of heart, arteries, capillaries, &veins:o Arteries

carry blood away from the heart

have muscular, elastic walls terminate in capillary beds

o Capillaries have very thin walls (endothelium only) are the site of exchange between the blood and body

cells

o Veins carry blood back to the heart have less muscle in their walls than arteries but the walls

are very elastic

begin at the end of capillary bedso Heart

a muscular pump (cardiac muscle)
http://www.dolphinear.com/library-fishsounds.htmhttp://www.news.cornell.edu/releases/June98/fish/sounds.htmlhttp://abcnews.go.com/sections/science/DailyNews/singingfish980625.htmlhttp://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.htmlhttp://www.notcatfish.com/ichthyology/weberian_apperatus.htmhttp://www.worldzone.net/music/singingvoice/images/glottis.gifhttp://www.biology.eku.edu/ritchiso/frogbreathing.htmhttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/respirat.htmhttp://cas.bellarmine.edu/tietjen/images/lung_structure_and_ventilation_i.htmhttp://www.biology.eku.edu/ritchiso/301notes6.htmhttp://www.biology.eku.edu/ritchiso/301notes6.htmhttp://www.accessexcellence.org/AE/AEC/CC/vessel.gifhttp://www.accessexcellence.org/AE/AEC/CC/vessel.gifhttp://www.accessexcellence.org/AE/AEC/CC/vessel.gifhttp://www.accessexcellence.org/AE/AEC/CC/vessel.gifhttp://www.biology.eku.edu/ritchiso/301notes6.htmhttp://www.biology.eku.edu/ritchiso/301notes6.htmhttp://cas.bellarmine.edu/tietjen/images/lung_structure_and_ventilation_i.htmhttp://campus.murraystate.edu/academic/faculty/terry.derting/anatomyatlas/respirat.htmhttp://www.biology.eku.edu/ritchiso/frogbreathing.htmhttp://www.worldzone.net/music/singingvoice/images/glottis.gifhttp://www.notcatfish.com/ichthyology/weberian_apperatus.htmhttp://www.ucmp.berkeley.edu/vertebrates/sarco/dipnoi.htmlhttp://abcnews.go.com/sections/science/DailyNews/singingfish980625.htmlhttp://www.news.cornell.edu/releases/June98/fish/sounds.htmlhttp://www.dolphinear.com/library-fishsounds.htm


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contains a pacemaker to regulate rate but rate can alsobe influenced by the Autonomic Nervous System

Vertebrate Hearts: (see HHMI Biointeractive - click on Vertebratecirculatorium)

Cartilaginous fishes

single-circuit heart with 4 chambers: sinus venosus, atrium, ventricle, &conus arteriosus

o the sinus venosus receives blood & is filled by suction when theventricle contracts & enlarges the pericardial cavity

o the atrium is a thin-walled muscular sac; an A-V valve regulatesflow between atrium & ventricle

o the ventricle has thick, muscular wallso the conus arteriosus leads into the ventral aorta (and a series of

conal valves in the conus arteriosus prevent the backflow ofblood)

Teleosts - heart is similar to that of cartilaginous fishes, except a bulbus arteriosus(a muscular extension of the ventral aorta) is present rather than a conus arteriosus(a muscular extension of the ventricle)

Used by permission ofJohn W. Kimble

Lungfish & amphibians - modifications are correlated with the presence of lungs& enable oxygenated blood returning from the lungs to be separated fromdeoxygenated blood returning from elsewhere (seeHHMI Biointeractive):

Partial or complete partition within atrium (complete in anurans and someurodeles)

Partial interventricular septum (lungfish) or ventricular trabeculae(amphibians) to maintain separation of oxygenated & unoxygenated blood Formation of a spiral valve in the conus arteriosus of many dipnoans and

amphibians. The spiral valve alternately blocks & unblocks the entrances tothe left and right pulmonary arches (sending unoxygenated blood to theskin & lungs).

Shortening of ventral aorta, which helps ensure that the oxygenated &unoxygenated blook kept separate in the heart moves directly into theappropriate vessels

5 = ventricle, 11 = right atrium, 12 = left atrium, 13 = conus arteriosus

Amniotes:

1 - Heart consists of 2 atria & 2 ventricles &, except in adult birds & mammals, asinus venosus

2 - Complete interatrial septum

3 - Complete interventricular septum only in crocodilians, birds, & mammals;partial septum in other amniotes

Used by permission ofJohn W. Kimball

Arterial channels - supply most tissues with oxygenated blood (but carrydeoxygenated blood to respiratory organs). In the basic pattern:

1 - the ventral aorta emerges from heart & passes forward beneath the pharynx

2 - the dorsal aorta (paired above the pharynx) passes caudally above thedigestive tract

3 - six pairs of aortic arches connect the ventral aorta with the dorsal aortas

Aortic arches of fishes- general pattern of development of arches in cartilaginousfishes:

1 - Ventral aorta extends forward below pharynx & connects developing aorticarches. The first pair of arches develop first.

2 - Segments of first pair are lost & remaining sections become efferentpseudobranchial arteries

3 - Other pairs of arches (2 - 6) give rise to pre- & posttrematic arteries

4 - Arches 2 - 6 become occluded; dorsal segments = efferent branchial arteries

& ventral segments = afferent branchial arteries

5 - Capillary beds develop within nine demibranchs

Result: Blood entering an aortic arch from ventral aorta must pass through gillcapillaries before proceeding to dorsal aorta

Teleosts:

o the same changes convert 6 pairs of embryonic aortic arches intoafferent & efferent branchial arteries

o arches 1 & 2 are usually lostLungfish:
http://www.hhmi.org/biointeractive/circulatorium/frames.htmlhttp://www.biology.eku.edu/RITCHISO/fishhearts.htmlhttp://www.ultranet.com/~jkimball/BiologyPages/A/AnimalHearts.htmlhttp://www.hhmi.org/biointeractive/circulatorium/frames.htmlhttp://www.hhmi.org/biointeractive/circulatorium/frames.htmlhttp://www.hhmi.org/biointeractive/circulatorium/frames.htmlhttp://www.auburn.edu/academic/classes/zy/0301/Topic12/Topic12.html#lungfishhttp://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9b/Frog_Heart_Model_3/frog_heart_model_3.htmhttp://www.ultranet.com/~jkimball/BiologyPages/A/AnimalHearts.htmlhttp://biology.uoregon.edu/classes/bi355f02/Topics%2002/topic%20jpgs%2002/06%20heart/Shark.jpeghttp://biology.uoregon.edu/classes/bi355f02/Topics%2002/topic%20jpgs%2002/06%20heart/Shark.jpeghttp://www.biology.eku.edu/RITCHISO/sharkcirc.htmlhttp://www.biology.eku.edu/RITCHISO/sharkcirc.htmlhttp://www.biology.eku.edu/RITCHISO/342notes9.html#fish#fishhttp://biology.uoregon.edu/classes/bi355f02/Topics%2002/topic%20jpgs%2002/06%20heart/Lungfish.jpeghttp://biology.uoregon.edu/classes/bi355f02/Topics%2002/topic%20jpgs%2002/06%20heart/Lungfish.jpeghttp://www.biology.eku.edu/RITCHISO/342notes9.html#fish#fishhttp://www.biology.eku.edu/RITCHISO/sharkcirc.htmlhttp://www.biology.eku.edu/RITCHISO/sharkcirc.htmlhttp://biology.uoregon.edu/classes/bi355f02/Topics%2002/topic%20jpgs%2002/06%20heart/Shark.jpeghttp://www.ultranet.com/~jkimball/BiologyPages/A/AnimalHearts.htmlhttp://bioweb.uwlax.edu/zoolab/Table_of_Contents/Lab-9b/Frog_Heart_Model_3/frog_heart_model_3.htmhttp://www.auburn.edu/academic/classes/zy/0301/Topic12/Topic12.html#lungfishhttp://www.hhmi.org/biointeractive/circulatorium/frames.htmlhttp://www.ultranet.com/~jkimball/BiologyPages/A/AnimalHearts.htmlhttp://www.biology.eku.edu/RITCHISO/fishhearts.htmlhttp://www.hhmi.org/biointeractive/circulatorium/frames.html


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o the pulmonary artery branches off the 6th aortic arch and suppliesthe swim bladder (& this is the same way that tetrapod lungs aresupplied)

Aortic arches of tetrapods - embryos have 6 pairs of aortic arches:

o but the 1st & 2nd arches are temporary & not found in adultso the 3rd aortic arches & the paired dorsal aortas anterior to arch 3

are called the internal carotid arteries

othe 4th aortic arches are called the systemic arches

o the 5th aortic arch is usually losto the pulmonary arteries branch off the 6th arches & supply blood to

the lungs

Source: http://www.uta.edu/biology/campbell/cva/3452circ.htm

Further modifications of tetrapod arches:

Amphibians:

o Urodeles - most terrestrial urodeles have 4 pairs of arches;aquatic urodeles typically have 3 pairs (III, IV, & VI)

o Anurans - have 4 arches early in development (larval stage); archVI develops a pulmonary artery (to lungs) while arches III, IV, & Vsupply larval gills. At metamorphosis:

aortic arch 5 is lost the dorsal aorta between arches 3 & 4 is lost, so blood

entering arch 3 (carotid arch) goes to the head

a segment (ductus arteriosus) of arch 6 is lost so bloodentering this arch goes to the skin & lungs

aortic arch 4 (systemic arch) on each side continue to thedorsal aorta & distributes blood to the rest of the body

Oxygenated blood from the left atrium & deoxygenatedblood from the right are largely kept separate in theventricle by:

Ventricular trabeculae Spiral valve in the conus arteriosus

o Reptiles - 3 aortic arches in adults (III, IV, & VI) Ventral aorta - no spiral valve but truncus arteriosus is

split into 3 separate passages: 2 aortic trunks & apulmonary trunk. As a result:

pulmonary trunk emerges from the rightventricle & connects with 6th aortic arches(deoxygenated blood from right atrium goes tolungs)

one aortic trunk comes out of left ventricle &carries oxygenated blood to the right 4th aortic

arch & to carotid arches

the other aortic trunk appears to come out ofright ventricle & leads to left 4th aortic arch.So, does the left 4th arch carry oxygenatedblood?

Turtles, snakes, & lizards - the interventricular septum is incomplete whereright & left systemic arches (4th) leave the ventricle & trabeculae in that region ofthe heart form a pocket called the cavum venosum. Oxygenated blood from theleft ventricle is directed into cavum venosum, which leads to the 2 systemic arches.As a result, both the left & right systemic arches receive oxygenated blood. (see

HHMI Biointeractive)

Source: http://www.ulg.ac.be/physioan/chapitre/ch2s2.htm

Crocodilians - ventricular septum is complete but a narrow channel called theForamen of Panizza connects the base of the right & left systemic

Documents

Vertebrate Systems Summary