2 Human Vertebra superior articular process neural arch transverse body(centrum)inferiorarticularprocessfacet forhead of ribtubercle of ribspinousprocess(neuralspine)
3 Human Vertebrae Intervertebral discs between (annulus and nucleus) Cervical Vertebrae – 7; #1 = atlas, #2 = axis; forked neural spine on #2-#7Thoracic Vertebrae – 12 (ribs articulate)Lumbar Vertebrae – 5 (no ribs)Sacral Vertebrae – 5; fusion begins at and usually completed at 25Coccygeal Vertebrae – 3-5; may become fused (= caudal vertebrae)
11 Vertebral Development Sclerotome = forms vertebral elementsMyotome = forms muscleBoth 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.
20 Comparative Vertebra Structure Hagfishes lack vertebral structures.Neural arches dorsal to notochord surrounds dorsal nerve cord.Neural spines project above neural archHemal arches ventral to notochord around blood vessels in “tail”Hemal spines project below hemal archnotochord
21 Vertebral CentraCentrum = solid bone or cartilage vertebral “segment;” “replaces” part of notochordIntervertebral pads = separate centra; derived, in part, from the notochordCentra evolved at least three times in vertebrates (Chondrichthys, Tetrapoda, & Amia + Teleosts)
22 Vertebral Regionalization Non-tetrapod vertebratesTrunk (Thoracic, Abdominal) vertebrae = anterior; often bear ribs, lack hemal archesCaudal vertebrae = posterior; rarely bear ribs, have hemal archesTetrapodsHave Ant. & Post. Articulatory ProcessesCervical vertebrae = neck vertebraeThoracic vertebrae = have ribs(Lumbar vertebrae = lack ribs)Sacral vertebrae = attached to pelvic girdle
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 canalAxis = second cervical vertebra in amniotes (Lissamphibians have only 1 cervical vertebra, an atlas.);odontoid process (dens) for rotation of atlas, large neural canalAtlas/Occipital Condyle joint = tiltingAtlas/Axis joint = rotation
26 Vertebral Regionalization GroupTrunk Vertebrae“fish”: hagfishes, lampreys, chondrichthyans, lungfish, actinopterygiians,many trunk (number greatly variable)amphibians1 cervical, few to many trunk, 1 sacralmammals7 cervical, trunk (9-20 thoracic & 4-7 lumbar), 3-5 sacral,turtles, lizards & snakes, & crocodilians7-9 cervical, few to many trunk (especially many in snakes), 2 sacral (0 in snakes)birds11-25 cervical, trunk, synsacralCaudal (“Tail”) Vertebrae vary greatly in number, even within groups.
27 Subphylum Vertebrata Actinopterygii Chondrichthys coelacanths amphibianshagfisheslungfisheslampreysMammaliaReptiliaR S G ATcentracentraaxis,>1 sacralvertebrae(Amniota)centra;atlas; sacralvertebrae; articulatory processes
28 Ribs Form within myosepta from cartilage. Dorsal ribs form where the myoseptum intersects the horizontal septumVentral ribs form where the myoseptum intersects the coelom somatic mesoderm.HOMOLOGY CONTROVERSY
32 SternumSternum (midventral endochondral element) where ribs often articulateEvolved independently in most groups.Mammalian sternum composed of multiple ossified elements (stern - ebrae); manubrium = 1st; xiphisternum/xiphoid process = last
36 Human Pectoral GirdleClavicle – (collar bone) large, connects acromion process of scapula and superior sternum; dermalScapula – (shoulder blade; endochondralAcromion process – contacts clavicleCoracoid processGlenoid fossaScapular bladeScapular spineclaviclesupra-sternalnotchacromion
37 Human Scapula acromion coracoid coracoid process process glenoid fossa scapularspinescapularblade
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.
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).ilpuisanteriorbird
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 manusHallux = “big toe;” digit I of pesPhalangeal formula = number of phalanges in each digit starting with digit I.(e.g., )
73 Bird Manus & Pes Birds: much fusion of elements Only 2 free carpals Carpometacarpus = distal carpals + metacarpals of digits III & IVTibiotarsus = tibia + proximal tarsalsTarsometatarsus = distal tarsals + metatarsals
74 Amniote Manus & PesTalus = 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 manusCalcaneus = fibulare with posterior process; forms heel
75 Genetralized Amniote Pes phalangesVIVdistal tarsalsmeta-tarsalsCalcaneus(fibulare)fibula54312III4312tibiaIIcentralesAstragalus(tibiale +intermedium)I