Download post cranial skeleton

Post-Cranial Skeleton
 Axial 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
neural
arch
superior
articular
process
transverse
process
body
(centrum)
inferior
articular
process
spinous
process
(neural
spine)
facet for
head of rib
facet for
tubercle of rib
Human Vertebrae
 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
Intervertebral Disc Problems
Atlas, Axis, & Other Cervical
Vertebrae
transverse foramen
(vertebral artery)
Thoracic Vert. Articulate w/ Ribs
costal
cartilage
Human Ribs & Sternum
 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
Human Sacral/Coccygeal Vert.
sacrum
coccyx
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.
Vertebral Development
Vertebrate Neurula (section)
somite
notochord
gut
intermediate
mesoderm
lateral
plate mesoderm
Vertebrate Embryo (section)
neural
crest
cells
sclerotome
dermatome
myotome
splanchnic
mesoderm
somatic
mesoderm
gut
intermediate
mesoderm
lateral
plate mesoderm
Vertebrate Embryo (section)
neural
crest
cells
sclerotome
dermatome
myotome
splanchnic
mesoderm
somatic
mesoderm
gut
intermediate
mesoderm
lateral
plate mesoderm
Vertebrate Embryo (section)
pigment cell
precursors
sclerotome
(neural crest)
ganglionic
neuron
precursors
dermatome
myotome
dorsal &
ventral
mesenteries
(splanchnic mesoderm)
(neural crest)
gut
coelom
lateral
plate mesoderm
Vertebrate Embryo (section)
vertebra
horizontal
septum
dermatome
myotome
dorsal &
ventral
mesenteries
(splanchnic mesoderm)
gut
coelom
lateral
plate mesoderm
Vertebrate Embryo (section)
vertebra
horizontal
septum
dermatome
myotome
dorsal
mesentery
(splanchnic
mesoderm)
gut
coelom
lateral
plate mesoderm
Fish Section
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)
Vertebral Regionalization
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
Bird Vertebral Regionalization
 Synsacral vertebrae = vertebrae attached
to pelvic girdle (homologs of sacral, lumbar,
some thoracic and some caudal vertebrae)
Cervical: Atlas & Axis
 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
Vertebral Regionalization
Group
“fish”: hagfishes, lampreys,
chondrichthyans, lungfish,
actinopterygiians,
Trunk Vertebrae
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
birds
snakes)
11-25 cervical, 3-10 trunk, 10-22
synsacral
 Caudal (“Tail”) Vertebrae vary greatly in
number, even within groups.
Subphylum Vertebrata
centra
centra
R S G AT
centra;
atlas; sacral
vertebrae;
articulatory
processes
axis,
>1 sacral
vertebrae
(Amniota)
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)
vertebra
horizontal
septum
dermatome
myotome
dorsal
mesentery
(splanchnic
mesoderm)
gut
coelom
lateral
plate mesoderm
Ribs
dorsal rib
ventral rib
Tetrapod Ribs
tuberculum
dorsal rib?
or
ventral rib?
capitulum
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
*
**
2 headed dorsal
ribs, ventral ribs
lost (Tetrapoda)
Ribs (of some kind)
(Gnathostomata) *segmental sternum
**solid sternum
Human Pectoral Skeleton
Human Pectoral Girdle
 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
clavicle
Scapular blade
supraScapular spine
sternal
acromion
notch
Human Scapula
acromion
coracoid
process
coracoid
process
glenoid fossa
scapular
spine
scapular
blade
acromion
coracoid process
Human Arm Bones
Human Arm External
styloid process
of ulna
lateral epicondyle
of humerus
olecranon process
of ulna
Human Hand (Manus)
IV
III
II
V
I
pisiform
Human Hand (Manus) Bones
Human Hand External
Human Pelvic Skeleton
Human Pevic Girdle
 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 Pelvic Girdle
ilium sacrum
coccyx
pubis
acetabulum
obturator
foramen
ischium
Human Pelvis External
iliac crest
(iliac spine)
iliac crest
(iliac spine)
Human Leg Bones
Human Leg External
lateral epicondyle
of femur
patella
medial epicondyle
of femur
head
of fibula
tibial tuberosity
tibial shaft (“shin”)
Human Pes
Human Foot (Pes) Bones
--Only Gnathostomes Have-Chondrichthyan Pectoral & Pelvic
 Pectoral girdle =cartilaginous scapulocoracoid
 Pelvic girdle = cartilaginous puboischiac bar
 Radials = support keratinous “fin rays”
puboischiac bar
scapulocoracoid
radials
Osteichthyan Pectoral Girdles
 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 Girdle
Posttemporal
Supracleithrum
Cleithrum
Clavicle
Interclavicle
Scapulocoracoid
Lepidotrichia
Radials
Osteichthyan Pectoral Girdles
 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
Tetrapod Pectoral Appendages
Scapula
Glenoid
fossa
Humerus
Ulna
Clavicle
Coracoid
Carpals
Interclavicle
Radius
Metacarpals
Phalanges
Amniote Pectoral Girdles
 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.
Echidna Skeleton
Dermal Pectoral Girdle
Group
interclavicle
clavicle
cleithrum
supracleithrum
posttemporal
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 Girdle
Group
Chondrichthys
reedfishes
sturgeons & paddlefish,
gars, & Amia
teleosts
lungfishes
amphibians
scapula
present,
fused to →
present
present,
fused to →
present
present,
fused to →
coracoid
present,
fused to ←
present
present,
fused to ←
present
present,
fused to ←
postcoracoid
absent
absent
absent
absent
absent
present
present
absent
sometimes fused to →
sometimes fused to ←
monotremes
present
present
present
Theria
present
absent
present, fused to
scapula (= coracoid
process)
Reptilia
present
present
sometimes fused to →
sometimes fused to ←
absent
Subphylum Vertebrata
**loss of interclavicle
*loss of clavicles
R S G AT
*
**
loss of
cleithrum,
supracleithrum,
dermal
& posttemporal
pec. girdle
(Osteichthys) (have “neck”)
(Tetrapoda)
pectoral &
pelvic appendages (Gnathostomata)
Subphylum Vertebrata
humerus,
(femur)
(Sarcopterygii)
radius, ulna,
metacarpals,
(tibia, femur,
metatarsals),
phalanges
(Tetrapoda)
Amniota
posterior
coracoid
loss of
interclavicle
& anterior
coracoid
loss
of
clavicles
furcula
clavicles &
interclavicle
in ventral shell
Osteichthyan Pelvic Girdles
turtle
articulates with plvic girdle in
sarcopterygiians. (Acetabulum
= articulation point)
il
is
pu
anterior
 ALL Endochondral
 Not in actinopts. = radials.
 3 “bones” in tetrapods.
 Ilium = contacts sacral vert.
 Pubis = Anterioventral
 Ischium = Posterioventral
 Femur = single radial
Tetrapod Pelvic Appendages
Ilium
Acetabulum
Femur
anterior
Fibula
Pubis
Tibia
Ischium
Tarsals
Metatarsals
Amniote Pelvic Girdles
 In Archosaurs the
bird
pu
anterior
acetabulum is “perforated.”
 In birds the 3 pelvic bones is
fuse (innominate bone);
form a synsacrum.
 In mammals the 3 pelvic
bones often fuse
(innominate bone).
il
Subphylum Vertebrata
ilium,
ischium, &
pelvic girdle pubis
(Tetrapoda)
lost; fused
basal radials
pelvic girdle
Amniota
synsacrum;
tibiotarsus;
tarsometatarsus
perforated
acetabulum (Archosauria)
Tetrapod Digit Terminology
 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)
Ancestral Tetrapod Manus
distal carpals metacarpals
ulnare
ulna
radius
intermedium
phalanges
V
IV
5
4
4 3 3
2 2
1 1
III
II
radiale
centrales
I
Ancestral Tetrapod Pes
distal tarsals metatarsals
fibulare
fibula
tibia
intermedium
phalanges
V
IV
5
4
4 3 3
2 2
1 1
III
II
tibiale
centrales
I
Human Manus
Bird Manus & Pes
 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
Amniote 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
Genetralized Amniote Pes
distal tarsals
Calcaneus
metatarsals
phalanges
V
IV
(fibulare)
fibula
tibia
5
4
4 3 3
2 2
1 1
III
II
Astragalus
(tibiale +
intermedium)
centrales
I
Amniota
calcaneus
(= “heel” on fibulare);
tibia-tarsal joint
carpometacarpus;
tibiotarsus;
astragalus / talus tarsometatarsus
(not an intratarsal joint)
(= tibiale + intermedium)