1. 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.

2. Human Vertebra superior articular process neural arch transverse
body
(centrum)
inferior
articular
process
facet for
head of rib
tubercle of rib
spinous
process
(neural
spine)

3. 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 and usually completed at 25
Coccygeal Vertebrae – 3-5; may become fused (= caudal vertebrae)

4. Human Vertebrae

5. Intervertebral Disc Problems

6. Atlas, Axis, & Other Cervical Vertebrae
transverse foramen
(vertebral artery)

7. Thoracic Vert. Articulate w/ Ribs
costal
cartilage

8. 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)

9. Human Ribs

10. Human Sacral/Coccygeal Vert.
coccyx
sacrum

11. 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.

12. Vertebral Development

13. Vertebrate Neurula (section)
somite
inter-
mediate
meso-
derm
lateral
plate mesoderm
notochord
gut

14. Vertebrate Embryo (section)
neural
crest
cells
dermatome
sclerotome
myotome
splanchnic
mesoderm
somatic
inter-
mediate
meso-
derm
gut
lateral
plate mesoderm

15. Vertebrate Embryo (section)
neural
crest
cells
dermatome
sclerotome
myotome
splanchnic
mesoderm
somatic
inter-
mediate
meso-
derm
gut
lateral
plate mesoderm

16. Vertebrate Embryo (section)
pigment cell
precursors
(neural crest)
ganglionic
neuron
dermatome
sclerotome
myotome
dorsal &
ventral
mesenteries
(splanchnic mesoderm)
coelom
gut
lateral
plate mesoderm

17. Vertebrate Embryo (section)
dermatome
vertebra
myotome
horizontal
septum
dorsal &
ventral
mesenteries
(splanchnic mesoderm)
coelom
gut
lateral
plate mesoderm

18. Vertebrate Embryo (section)
dermatome
vertebra
myotome
horizontal
septum
coelom
gut
dorsal
mesentery
(splanchnic
mesoderm)
lateral
plate mesoderm

19. Fish Section

20. 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

21. 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)

22. 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

23. Vertebral Regionalization

24. Bird Vertebral Regionalization
Synsacral vertebrae = vertebrae attached to pelvic girdle (homologs of sacral, lumbar, some thoracic and some caudal vertebrae)

25. 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

26. Vertebral Regionalization
Group
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, 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, trunk, synsacral
Caudal (“Tail”) Vertebrae vary greatly in number, even within groups.

27. Subphylum Vertebrata Actinopterygii Chondrichthys coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
R S G AT
centra
centra
axis,
>1 sacral
vertebrae
(Amniota)
centra;
atlas; sacral
vertebrae; articulatory processes

28. 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

29. Vertebrate Embryo (section)
dermatome
vertebra
myotome
horizontal
septum
coelom
gut
dorsal
mesentery
(splanchnic
mesoderm)
lateral
plate mesoderm

30. Ribs
dorsal rib
ventral rib

31. Tetrapod Ribs
capitulum
tuberculum
dorsal rib? or
ventral rib?

32. 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

33. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia * **
2 headed dorsal
ribs, ventral ribs
lost (Tetrapoda)
Ribs (of some kind)
(Gnathostomata)
*segmental sternum
**solid sternum

34. Appendicular
Skeleton

35. Human Pectoral Skeleton

36. 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
Scapular blade
Scapular spine
clavicle
supra-
sternal
notch
acromion

37. Human Scapula acromion coracoid coracoid process process glenoid fossa
scapular
spine
scapular
blade

38. Human Arm Bones

39. Human Arm External styloid process of ulna lateral epicondyle
of humerus
olecranon process
of ulna

40. Human Hand (Manus) I
III II IV V
pisiform

41. Human Hand (Manus) Bones

42. Human Hand External

43. Human Pelvic Skeleton

44. 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

45. Human Pelvic Girdle coccyx ilium sacrum pubis acetabulum obturator
foramen
ischium

46. Human Pelvis External iliac crest iliac crest (iliac spine)

47. Human Leg Bones

48. Human Leg External lateral epicondyle medial epicondyle of femur
patella
head
of fibula
tibial tuberosity
tibial shaft (“shin”)

49. Human Pes

50. Human Foot (Pes) Bones

51. Comparative
Appendicular
Skeletons

52. --Only Gnathostomes Have-- Chondrichthyan Pectoral & Pelvic
Pectoral girdle =cartilaginous scapulocoracoid
Pelvic girdle = cartilaginous puboischiac bar
Radials = support keratinous “fin rays”
scapulocoracoid
puboischiac bar
radials

53. 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”

54. Osteichthyan Pectoral Girdle
Cleithrum
Supracleithrum
Posttemporal
Clavicle
Interclavicle
Lepido-
trichia
Radials
Scapulo-
coracoid

55. 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

56. Tetrapod Pectoral Appendages
Coracoid
Scapula
Clavicle
Interclavicle
Glenoid
fossa
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges

57. 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.

58. Echidna Skeleton

59. Dermal Pectoral Girdle
Group
inter-clavicle
clavicle
cleithrum
supra-cleithrum
post-
temporal
reedfishes and sturgeons
present
gars
absent
teleosts & Amia
lungfishes
amphibians
monotremes
Theria
turtles, birds, & lizards/snakes
crocodilians

60. Endochondral Pectoral Girdle
Group
scapula
coracoid
postcoracoid
Chondrichthys
present, fused to →
present, fused to ←
absent
reedfishes
present
sturgeons & paddlefish, gars, & Amia
teleosts
lungfishes
amphibians
sometimes fused to →
sometimes fused to ←
monotremes
Theria
present, fused to scapula (= coracoid process)
Reptilia

61. Subphylum Vertebrata Actinopterygii Chondrichthys coelacanths
**loss of interclavicle
*loss of clavicles
Actinopterygii
Chondrichthys
coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
R S G AT * **
loss of
cleithrum,
supracleithrum,
& posttemporal
(have “neck”)
(Tetrapoda)
dermal
pec. girdle
(Osteichthys)
pectoral &
pelvic appendages (Gnathostomata)

62. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
radius, ulna,
metacarpals,
(tibia, femur,
metatarsals),
phalanges
(Tetrapoda)
humerus, (femur)
(Sarcopterygii)

63. Amniota lizards & snakes crocodylians montremes marsupials eutherians
turtles
lizards & snakes
crocodylians
birds
posterior
coracoid
loss of
interclavicle
& anterior
coracoid
loss of
clavicles
furcula
clavicles &
interclavicle
in ventral shell

64. Osteichthyan Pelvic Girdles
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)
turtle il is
anterior pu

65. Tetrapod Pelvic Appendages
Ilium
Ischium
Pubis
Acetabulum
Femur
Fibula
Tibia
Tarsals
Metatarsals
anterior

66. Amniote Pelvic Girdles
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). il pu is
anterior
bird

67. Subphylum Vertebrata Chondrichthys Actinopterygii coelacanths
amphibians
hagfishes
lungfishes
lampreys
Mammalia
Reptilia
ilium, ischium, & pubis
(Tetrapoda)
pelvic girdle
lost; fused basal radials
pelvic girdle

68. Amniota Lizards & snakes crocodilians montremes marsupials eutherians
turtles
Lizards & snakes
crocodilians
birds
synsacrum;
tibiotarsus;
tarsometatarsus
perforated
acetabulum (Archosauria)

69. 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., )

70. Ancestral Tetrapod Manus
phalanges V IV
distal carpals
meta-
carpals
ulnare
radiale
ulna 5 4 3 1 2
III 4 3 1 2
inter-
medium
radius II
centrales I

71. Ancestral Tetrapod Pes
phalanges V IV
distal tarsals
meta-
tarsals
fibulare
tibiale
fibula 5 4 3 1 2
III 4 3 1 2
inter-
medium
tibia II
centrales I

72. Human Manus

73. 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

74. 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

75. Genetralized Amniote Pes
phalanges V IV
distal tarsals
meta-
tarsals
Calcaneus
(fibulare)
fibula 5 4 3 1 2
III 4 3 1 2
tibia II
centrales
Astragalus
(tibiale +
intermedium) I

76. Amniota lizards & snakes crocodilians monotremes marsupials eutherians
turtles
lizards & snakes
crocodilians
birds
calcaneus
(= “heel” on fibulare);
tibia-tarsal joint
(not an intratarsal joint)
carpometacarpus;
tibiotarsus;
tarsometatarsus
astragalus / talus
(= tibiale + intermedium)