vertebra of scoliodon

Comments :

It consists of 130 vertebrae divided into trunk and caudal regions. 

Vertebrae are amphicoelous. 

  •  Trunk vertebra :- It consists of neural spine, neural canal, neural arch, passage for notochord and transverse processes a ventral, thick, cylindrical centrum, transverse processes.
  • Caudal vertebra :- It differs from trunk vertebra because its transverse processes meet and fuse to form below a haemal arch enclosing a haemal canal, spine. Upper section shows neural spine, neural canal, neural arch and uncalcified area in centrum.


Comments :

  • Atlas (Dorsal view):-  (i) It is a ring-shaped bone with reduced centrum on one face only.
    (ii) Anteriorly centrum contains two large concave facets for articulation with occipital condyles.
    (iii) Pre-zygapophyses absent, neural spine reduced. post-zygapophyses present and neural arch present.
  • Atlas vertebra (Ventral view). It shows neural canal, post-zygapophysis centrum and anterior facet, for occipital condyle.
  • Typical vertebra-2nd to 7th (Lateral view) :- (i) It is a typical vertebra. (ii) It is also nearly a ringshaped bone. (iii) Centrum procoelous with anterior concave face and posterior convex faces.
    (iv) Neural spine is blunt and transverse processes are long and tapering on their side of centrum.
    (v) Pre-zygapophyses (pre-zygp) are inwardly and upwardly directed, while post-zygapophyses (post-zygp) are downwardly and outwardly directed. (vi) The second vertebra is like other typical
    vertebrae except that its neural spine is short and transverse processes broad.
  • Typical vertebra (posterior view :- It shows neural spine, neural canal, pre ygapophysis transverse processes and post zapophysis.
  • Typical vertebra (Dorsal view) :- Structures seen are pre-zygapophysis, neural arch, post zygapophysis centrum and neural spine.
  • Typical vertebra (Anterior view) :- It has transverse process, neural spine, post-zygapophysis, pre-zygapophysis, anterior concavity of centrum and neural canal.
  • Second vertebra (Anterior view) :- Structures seen are neural spine, post-zygapophysis, transverse process, anterior concavity of centrum pre-zygapophysis and neural arch.
  • Fourth vertebra (Anterior view) :- It shows neural spine, transverse process, anterior concavity of cemrum and pre-zygapophysis.
  • Eighth vertebra (Ventral view) :- (i) Centrum in amphicoelus or biconcave. (ii) Anterior part of centrum receives posterior concavity of seventh vertebra and posterior part receives anterior convexity of ninth vertebra. (iii) Other structures are transverse processes, pre-zygapophysis and post-zygapophysis.
  • Ninth vertebra (Ventral view) :- It has anterior convexity of centrum, pre-zygapophysis, iliac facet, transverse process and posterior convexity of centrum.
  • Ninth vertebra (Dorsal view) :- Structures seen are neural spine, pre-zygapophysis, iliac facet, transverse process and posterior convexity of centrum.
  • Urostyle:- (i) It is the last part of vertebral column and, quite elongated. (ii) Centrum is rod-shaped which contains two concavities anteriorly for articulation with the ninth vertebra, and a cavity for
    the terminal part of the spinal cord.



Comments :-

  • Atlas (Anterior view) :- (i) It is also a ring-shaped bone, composed of three pieces, two dorso-Iateral and one ventral. (ii) Centrum and transverse processes are absent. (iii) During living condition, the
    neural canal is divided into dorsal and ventrai neural canals by a ligament. (iv) It contains anterior concavity for occipital condyle.
  • Atlas (Posterior view) :- Structures seen are dorso-Iateral piece, dorsal neural canal, ligament, ventral neural canal and facet for odontoid process.
  • Axis (Lateral view) :- (i) It is the second cervical vertebra. (ii) Transverse processes are absent. (iii) Pre-zygapophyses reduced, while post-zygapophyses well developed. (iv) Neural spine large and crest-like (v) Centrum contains a spine-like process below odontoid process and a hypapophysis.
  • Typical cervical (Lateral view) :- (i) Centrum elongated and strongly procoelous. (ii) It contains a ventral backwardly-directed hypapophysis. (iii) Neural spine is crest-like. (iv) Neural arch contains a pair of anterior upwardly-directed pre-zygapophyses and a pair of posterior backwardly-directed post-zygapophyses. (v) Behind third vertebra, each cervical contains a pair of lateral facets for articulation of ribs.
  • Thoraco-Iumber (Lateral view) :- (i) They are larger than cervical with strongly proceolous centrum and well developed pre- and post-zygapophyses. (ii) Hypapophysis absent. (iii) At the junction of
    neural arch and centrum a distinct capitular facet is present to articulate with rib.
  • Thoracoolumber (Dorsal view). Structure seen are neural arch, pre-zygapophysis, capitular facet for rib, neural spine, post-zygapophysis and centrum.
  • First sacral. (i) It supports pelvic girdle. (ii) Centrum is procoelous. (iii) Pre-and post-zygapophyses well developed. (iv) Neural spine slightly crest-like. (v) Transverse processes greatly expanded and notched to articulate with ilia.
  • Second sacral (Lateral view) :- (i) It resembles first sacral in having procoelous centrum, low crestlike neural spine neural notch and well-developed pre- and post-zygapophyses. (ii) It differs from first
    sacral in the absence of a notch in transverse processes.
  • Anterior caudal :- (i) It is like sacral superficially, but it contains a long centrum, slender neural spine and transverse processes and fairly developed pre- and post-zygapophyses. (ii) Specific feature
    of the vertebra is the presence of a Y -shaped chevron bone beneath centrum.



Comments :

  • Atlas. (i) Atlas or first cervical is ring-shaped, roughly triangular bone, composed of two dorso-Iateral and one ventral pieces. (ii) Concavity for occipital condyle and a notch for odontoid process. (iii) Centrum, neural spine, ribs, transverse processes and pre-zygapophyses are absent.
  • Atlas (Ventral view) :- Structures seen are post-zygapophyses, neural canal, ventral piece, cavity for occipital condyle and facet for odontoid process.
  • Axis or epistropheus :- (i) It is also called as second cervical which is without transverse processes, ribs and vertebral canals. (ii) Neural spine, pre-zygapophyses and post-zygapophyses present.
    (iii) Centrum heterocoelous and produced into an anterior odontoid process.
  • Typical cervical (Dorsal view) :- (i) 14 in number. (ii) Centrum heterocoelous. (iii) Neural arch short and neural spine rudimentary. (iv) Transverse processes short and irregular and fused with thin,
    backwardly directed reduced cervical ribs. (v) Pre-zygapophyses flat while post-zygapophyses project downwards and outwards.
  • Typical cervical (Ventral view) :- Structures seen are heterocoelous centrum, transverse process, cervical rib and post-zygapophyses.
    Fused thoracic. (i) Second to fifth 7 thoracic vertebrae are fused. (ii) Due to complete fusion, neural spines, transverse processes and hypapophyses look like plates which are perforated by intervertebral
  • Free thoracic :- (i) First and sixth thoracic vertebrae are free. (ii) Each vertebra has heterocoelous
    centrum, hypapophysis and it also carries double-headed thoracic ribs.
  • Posterior cervical (Anterior view) :- Structures seen are neural spine, neural canal, transverse hypophysis, heterocoelus centrum. vertebral enterial foramen, pre-zygapophysis neural arch and postzygapophysis.
  • Free thoracic (Anterior view) :- (i) First and sixth vertebral are free. (ii) Each vertebrae contains neural arch, post-zygapophysis, pre-zygapophysis, hypophysis, heterocoelus centrum transverse
    process, neural canal and neural spine.
  • Fused thoracic (Lateral view) :- (i) Second, third, fourth, fifth and seventh vertebrae are fused together.
    (ii) Due to complete fusion, neural spines, transverse processes and hypophysis look like plates which are perforated by intervertebral gap.
  • Synsacrum (Dorsal view) :- (i) Synsacrum in formed by last thoracic, 6 lumber, 2 sacral and 7 caudal vertebrae. (ii) Thoracic vertebrae contain a pair of thoracic ribs. (iii) Lumber vertebrae are firmly fused together with free transverse process and without hypophysis. (iv) Sacral vertebral fused together to form bony plate. (v) Other structures seen are pre-zygapophysis centrum, fused neural spine and caudal vertebra.
  • Synsacrum (Ventral view) :- Structures seen are pre-zygapophysis, thoracic vertebra, transverse process, lumber vertebra, fused transverse process of sacral vertebrae and bifurcated transverse processes and caudal vertebra.
  • Free caudal :- It has bifurcated neural spine, neural canal, centrum and transverse process.
  • Pygostyle :- It shows upper surface and fused caudal vertebrae.


rabbit vertebral column

Comments :-

  • Atlas :- (i) It is fIrst cervical and signet-ring like. (ii) Centrum, zygapophyses absent and neural spine rudimentary. (iii) On the sides are present flattened cervical ribs, the so-called transverse processes.
  • Atlas (Anterior view) :- (i) It has 2 anterior facets feroccipital condyle, (ii) Other structures are neural spine, neural canal, vertebral arterial canal, transverse process and neural arch.
  • Atlas (Posterior view) :- (i) Posteriorly it has facets for odontoid processes and articular facet for axis.
    (ii) Other structures are neural arch, neural spine, neural canal and vertebraterial canal. (iii) During living condition neural canal is divided into dorsal and ventral parts by a ligament.
  • Axis (Lateral view) :- (i) It is second cervical. (ii) Neural spine is flattened, antero-posteriorly elongated and ridge-like. (iii) Cervical ribs or so-called transverse processes are small. (iv) Centrum contains peg-like odontoid process. (v) Pre-zygapophyses absent. Other structures are neural arch, articular surface for atlas and post-zygapophysis.
  • Typical cervical (Anterior view) :- (i) Rest of the cervicals are typical having small neural spine, large neural arch, flattened centrum, pre-zygapophyses and post-zygapophyses. (ii) Transverse
    process bifurcated and perforated by a vertebraterial canal and facet for cervical rib present.
  • Anterior thoracic (Anterior view) :- (i) It contains a backwardly-oriented neural spine. (ii) Neural arch has upwardly-directed pre-zygapophyses and downwardly-directed post-zygapophyses.
    (iii) Transverse processes short and contain facets for tuberculum of ribs. (iv) Centrum short.
  • Anterior thoracic (Lateral view) :- Structures seen are long tilted neural spine, facets of tuberculum of rib post-zygapophysis, centrum, post-zygapophysis, intervertebral notch, centrum and pre-zygapophysis.
  • Posterior thoracic (Lateral view) :- (i) Last 4 or 5 thoracic vertebrae differ from anterior ones in having a long centrum, short neural spine, distinct zygapophyses and reduced transverse processes.
    (ii) It contains capitular facets, metapophyses and anapophyses. It has invertebral notch.
  • Anterior lumbar (Anterior view) :-(i) Out of 7, fIrst two called as anterior lumbar vertebrae.
    (ii) Neural arch on either side contains an anteriorly-directed process called metapophysis which bears pre-zygapophysis, and a posteriorly and backwardly-directed anapophysis which bears post-zygapophysis. Hypophysis present.
  • Posterior lumbar (Lateral view) :- (i) 3rd to 7th vertebrae are called as posterior lumbar. (ii) The resemble anterior lumbar in all respects except that a ridge-like hypapophysis is prevent below centrum.
  • Sacrum (Lateral view) :- (i) Sacral vertebrae (4 in number) are fused to form a compact bone supporting pelvis. (ii) The neural spines, zygapophyses and intervertebral formina are peculiar.
  • Sacrum (Dorsal view) :- Structures seen as neural spine, post-zygapophyses intervertebral foramen, 1st sacral vertebra, centrum, pre-zygapophysis and articular facet for ilium.
  • Caudal (Dorsal view) :- Structures seen, are neural spines, vertebral, post-zygapophysis, and pre-zygapophysis

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