Post-Cranial Skeleton Axial skeleton = vertebrae, sternum, & ribs; endochondral bone. Appendicular...
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Transcript of Post-Cranial Skeleton Axial skeleton = vertebrae, sternum, & ribs; endochondral bone. Appendicular...
Post-Cranial SkeletonAxial skeleton = vertebrae, sternum,
& ribs; endochondral bone.
Appendicular Skeleton
Pectoral skeleton supports pectoral appendages (arms); dermal and endochondral bone.
Pelvic skeleton supports pelvic appendages (legs); endochondral bone.
Human Vertebra
body(centrum)
spinousprocess(neuralspine)
superiorarticularprocess
inferiorarticularprocess
transverseprocess
neuralarch
facet forhead of rib
facet fortubercle of rib
Intervertebral discs between (annulus and nucleus)
Cervical Vertebrae – 7; #1 = atlas, #2 = axis; forked neural spine on #2-#7
Thoracic Vertebrae – 12 (ribs articulate)
Lumbar Vertebrae – 5 (no ribs)
Sacral Vertebrae – 5; fusion begins at 16-18 and usually completed at 25
Coccygeal Vertebrae – 3-5; may become fused (= caudal vertebrae)
Human Vertebrae
Ribs – 12; on thoracic vertebrae
True Ribs – 7; contact sternum directly
False Ribs – 5; don’t contact sternum directly
“False” / Vertebrochondral Ribs – 3; fuse to a single costal cartilage element
Floating Ribs – 2; don’t contact sternum
Sternum – segments fuse to form 3 bones; manubrium, body, xiphoid process (x.p. doesn’t articulate with ribs)
Human Ribs & Sternum
Vertebral Development Sclerotome = forms vertebral elements
Myotome = forms muscle
Both separated into segments when the somites form.
Vertical myosepta exist between segments of myotome (derived from the somite) .
The myotome is also divided by a horizontal septum.
Neural & hemal arches are centered on the vertical myosepta.
Vertebrate Embryo (section)neuralcrestcells
dermatome
sclerotome
myotome
splanchnicmesoderm
somaticmesoderm
gut
inter-mediatemeso-derm
lateralplate mesoderm
Vertebrate Embryo (section)
gut
inter-mediatemeso-derm
lateralplate mesoderm
neuralcrestcells
dermatome
sclerotome
myotome
splanchnicmesoderm
somaticmesoderm
Vertebrate Embryo (section)
gutcoelom
pigment cell precursors(neural crest)
ganglionicneuron precursors(neural crest)
dermatome
sclerotome
myotome
dorsal & ventralmesenteries(splanchnic mesoderm) lateral
plate mesoderm
Vertebrate Embryo (section)
gut
dermatome
vertebra
myotome
horizontalseptum
dorsal & ventralmesenteries(splanchnic mesoderm)
coelom
lateralplate mesoderm
Vertebrate Embryo (section)
gut
dermatome
vertebra
myotome
horizontalseptum
dorsalmesentery(splanchnic mesoderm)
coelom
lateralplate mesoderm
Comparative Vertebra Structure Hagfishes lack vertebral structures. Neural arches dorsal to notochord
surrounds dorsal nerve cord. Neural spines project above neural
arch Hemal arches ventral to notochord
around blood vessels in “tail” Hemal spines project below hemal arch
notochord
Vertebral Centra Centrum = solid bone or
cartilage vertebral “segment;” “replaces” part of notochord
Intervertebral pads = separate centra; derived, in part, from the notochord
Centra evolved at least three times in vertebrates (Chondrichthys, Tetrapoda, & Amia + Teleosts)
Non-tetrapod vertebrates
Trunk (Thoracic, Abdominal) vertebrae = anterior; often bear ribs, lack hemal arches
Caudal vertebrae = posterior; rarely bear ribs, have hemal arches
Tetrapods
Have Ant. & Post. Articulatory Processes
Cervical vertebrae = neck vertebrae
Thoracic vertebrae = have ribs
(Lumbar vertebrae = lack ribs)
Sacral vertebrae = attached to pelvic girdle
Vertebral Regionalization
Synsacral vertebrae = vertebrae attached to pelvic girdle (homologs of sacral, lumbar,
some thoracic and some caudal vertebrae)
Bird Vertebral Regionalization
Atlas = first cervical vertebra in tetrapods;
reduced centrum, large neural canal
Axis = second cervical vertebra in amniotes (Lissamphibians have only 1 cervical vertebra, an atlas.);
odontoid process (dens) for rotation of atlas, large neural canal
Atlas/Occipital Condyle joint = tilting
Atlas/Axis joint = rotation
Cervical: Atlas & Axis
Vertebral RegionalizationGroup Trunk Vertebrae“fish”: hagfishes, lampreys, chondrichthyans, lungfish, actinopterygiians,
many trunk (number greatly variable)
amphibians 1 cervical, few to many trunk, 1 sacral
mammals 7 cervical, 13-27 trunk (9-20 thoracic & 4-7 lumbar), 3-5 sacral,
turtles, lizards & snakes, & crocodilians
7-9 cervical, few to many trunk (especially many in snakes), 2 sacral (0 in
snakes)
birds 11-25 cervical, 3-10 trunk, 10-22 synsacral
Caudal (“Tail”) Vertebrae vary greatly in number, even within groups.
Subphylum Vertebrata
hagfis
hes
lam
preys
Chondrichth
ys
Actin
optery
gii
coel
acan
ths
lungfis
hes
amphib
ians
Mam
mal
ia
Reptil
iace
ntr
a
R S G AT
cen
tra
axis,>1 sacralvertebrae(Amniota)
centra; atlas; sacral
vertebrae; articulatory processes
Ribs Form within myosepta
from cartilage.
Dorsal ribs form where the myoseptum intersects the horizontal septum
Ventral ribs form where the myoseptum intersects the coelom somatic mesoderm.HOMOLOGY CONTROVERSY
Vertebrate Embryo (section)
gut
dermatome
vertebra
myotome
horizontalseptum
dorsalmesentery(splanchnic mesoderm)
coelom
lateralplate mesoderm
Sternum Sternum (midventral endochondral element)
where ribs often articulate
Evolved independently in most groups.
Mammalian sternum composed of multiple ossified elements (stern - ebrae); manubrium = 1st; xiphisternum/xiphoid process = last
Subphylum Vertebrata
hagfis
hes
lam
preys
Chondrichth
ys
Actin
optery
gii
coel
acan
ths
lungfis
hes
amphib
ians
Mam
mal
ia
Reptil
ia
Ribs (of some kind)(Gnathostomata)
2 headed dorsal ribs, ventral ribs lost (Tetrapoda)
* **
*segmental sternum
**solid sternum
claviclesupra-sternalnotch
acromion
Clavicle – (collar bone) large, connects acromion process of scapula and superior sternum; dermal
Scapula – (shoulder blade; endochondral
Acromion process – contacts clavicle
Coracoid process
Glenoid fossa
Scapular blade
Scapular spine
Human Pectoral Girdle
coracoid process
Human Scapulaacromion
acromion
coracoid process
glenoid fossa
coracoidprocess
scapularblade
scapularspine
Innominate Bone – pelvis; 3 pairs bones; connects to sacral vertebrae; endochondral
Ilium – fused to sacrum
Ischium – posterior & inferior
Pubis – anterior & inferior
Obturator foramen – btw. pubis & ischium
Acetabulum – femur
articulates
Human Pevic Girdle
Human Leg External
patella
tibial tuberosity
lateral epicondyleof femur
medial epicondyleof femur
tibial shaft (“shin”)
headof fibula
Pectoral girdle =cartilaginous scapulocoracoid
Pelvic girdle = cartilaginous puboischiac bar
Radials = support keratinous “fin rays”
--Only Gnathostomes Have--Chondrichthyan Pectoral & Pelvic
scapulocoracoid puboischiac bar
radials
Scapulocoracoid (or scapula & coracoid) = endochondral; articulate(s) with radials (also endochondral)
Extensive, dermal pectoral girdle
Posttemporal, supracleithrum, cleithrum, clavicle, and interclavicle (median & unpaired)
Fin rays = dermal bony rods (support most of fin); modified lamellar bone “scales”
Osteichthyan Pectoral Girdles
Radials
Scapulo-coracoid
Osteichthyan Pectoral Girdle
Lepido-trichia
Cleithrum
Supracleithrum
Posttemporal
ClavicleInterclavicle
Actinopterygiians - loss of ventral dermal bones (Teleosts & Amia lack clavicles & interclavicles. Gars lack interclavicles, but have clavicles.)
Tetrapods - loss of dorsal dermal bones
(lack posttemporal, supracleithrum, & cleithrum)
Humerus = single radial articulates with “scapulocoracoid” in sarcopterygiians. (Glenoid fossa = articulation point) In Tetrapods - Humerus Radius & Ulna Carpals Metacarpals Phalanges
Osteichthyan Pectoral Girdles
Tetrapod Pectoral Appendages
Coracoid
Scapula
Clavicle
Interclavicle
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges
Glenoidfossa
Clavicles & interclavicle in turtle ventral shell.
furcula = fused clavicles & interclavicle in birds.
postcoracoid = endochondral ossification unique to mammals; fuses to scapula in therians (= coracoid process of scapula)
Therian mammals lack interclavicle and coracoid.
Amniote Pectoral Girdles
Dermal Pectoral GirdleGroup inter-
clavicleclavicle cleithrum supra-
cleithrumpost-
temporal
reedfishes and sturgeons
present present present present present
gars absent present present present present
teleosts & Amia absent absent present present present
lungfishes present present present present absent
amphibians present present absent absent absent
monotremes present present absent absent absent
Theria absent present absent absent absent
turtles, birds, & lizards/snakes
present present absent absent absent
crocodilians present absent absent absent absent
Endochondral Pectoral GirdleGroup scapula coracoid postcoracoid
Chondrichthys present, fused to → present, fused to ← absent
reedfishes present present absent
sturgeons & paddlefish, gars, & Amia
present, fused to → present, fused to ← absent
teleosts present present absent
lungfishes present, fused to → present, fused to ← absent
amphibians presentsometimes fused to →
presentsometimes fused to ←
absent
monotremes present present present
Theria present absent present, fused to scapula (= coracoid
process)
Reptilia presentsometimes fused to →
presentsometimes fused to ←
absent
Subphylum Vertebrata
hagfis
hes
lam
preys
Chondrichth
ys
Actin
optery
gii
coel
acan
ths
lungfis
hes
amphib
ians
Mam
mal
ia
Reptil
ia
loss ofcleithrum,supracleithrum,& posttemporal(have “neck”) (Tetrapoda)
R S G AT
***
**loss of interclavicle*loss of clavicles
pectoral & pelvic appendages (Gnathostomata)
dermalpec. girdle(Osteichthys)
Subphylum Vertebrata
hagfis
hes
lam
preys
Chondrichth
ys
Actin
optery
gii
coel
acan
ths
lungfis
hes
amphib
ians
Mam
mal
ia
Reptil
ia
radius, ulna,metacarpals, (tibia, femur,metatarsals),phalanges(Tetrapoda)
humerus, (femur)
(Sarcopterygii)
Amniota
montre
mes
mar
supia
ls
euth
eria
ns
turtl
es
lizar
ds & s
nakes
croco
dylia
ns
birds
furculaclavicles &interclaviclein ventral shell
posteriorcoracoid
loss of interclavicle& anteriorcoracoid
lossof clavicles
ALL Endochondral
Not in actinopts. = radials.
3 “bones” in tetrapods.
Ilium = contacts sacral vert.
Pubis = Anterioventral
Ischium = Posterioventral
Femur = single radial articulates with plvic girdle in sarcopterygiians. (Acetabulum = articulation point)
Osteichthyan Pelvic Girdlesanterior
turtle
is
il
pu
Tetrapod Pelvic AppendagesIlium
IschiumPubis
Acetabulum
Femur
Fibula
TibiaTarsals
Metatarsals
anterior
In Archosaurs the acetabulum is “perforated.”
In birds the 3 pelvic bones fuse (innominate bone); form a synsacrum.
In mammals the 3 pelvic bones often fuse (innominate bone).
Amniote Pelvic Girdlesanterior
bird
is
ilpu
Subphylum Vertebrata
hagfis
hes
lam
preys
Chondrichth
ys
Actin
optery
gii
coel
acan
ths
lungfis
hes
amphib
ians
Mam
mal
ia
Reptil
ia
ilium, ischium, & pubis (Tetrapoda)
pelvic girdlelost; fused basal radials
pelvic girdle
Amniota
montre
mes
mar
supia
ls
euth
eria
ns
turtl
es
Lizard
s & s
nakes
croco
dilian
s
birds
synsacrum;tibiotarsus;
tarsometatarsusperforatedacetabulum (Archosauria)
Manus = “hand”
Pes = “foot”
Digits numbered anterior to posterior. Ancestrally 5 digits per limb in amniotes .
Pollux = “thumb;” digit I of manus
Hallux = “big toe;” digit I of pes
Phalangeal formula = number of phalanges in each digit starting with digit I.
(e.g., 2-3-3-3-3)
Tetrapod Digit Terminology
Ancestral Tetrapod Manusphalanges
meta-carpals
radius
ulna
ulnare
radiale
inter-medium
distal carpals
54
3
12
4 3
1
2
I
II
III
IVV
centrales
Ancestral Tetrapod Pesphalanges
meta-tarsals
tibia
fibula
fibulare
tibiale
inter-medium
distal tarsals
54
3
12
4 3
1
2
I
II
III
IVV
centrales
Birds: much fusion of elements
Only 2 free carpals
Carpometacarpus = distal carpals + metacarpals of digits III & IV
Tibiotarsus = tibia + proximal tarsals
Tarsometatarsus = distal tarsals + metatarsals
Bird Manus & Pes
Talus = tibiale + intermedium (called Astragalus in non-mammals)
Mammals - Maximum of only 1 free centrale (humans = 0 in manus, 1 in pes)
Pisiform = sesamoid ossification on manus
Calcaneus = fibulare with posterior process; forms heel
Amniote Manus & Pes
Genetralized Amniote Pesphalanges
meta-tarsals
tibia
fibula
Calcaneus (fibulare)
Astragalus(tibiale + intermedium)
distal tarsals
54
3
12
4 3
1
2
I
II
III
IVV
centrales