Defines the long axis of the body into the Notochord and Vertebral Column.

Both are sites for muscles attachment, resisit compression, support weight, and prevent telescoping of the body.

As VC increases, NC decreases.

General Form: Arches on either side of a centrum.

Evolved to protect the spinal cord and the dorsal aorta then became a site for muscles attachment.

Later suspended the body to allow movement to land.

For from mesenchyme that separates from somites (somite from mesoderm)

Spine projects from teh arches and vary in morphology.

Direction in which it receives mechanical forces in the least stressful direciton -> receives as compression.

Spines are oriented so that the forces imposed by the muscles are experienced as compression.

Proportional to the amount of mechanical leverage the muscle must exert to stabilize the column.

(if the muscle exerts alot, there is a big spine)

Linked successively into a chain.

Vertebrae are separated by intervertebral disks (mammals) or invertebra.

Vertebrae vary in structure, extent of ossification, and degree of NC replacement.

Types of centra are determined by the shape at the ends.

Both ends are flat to best recieve and distribute compressive forces in the column.

ex: fish

Both surfaces are concave, limited motion in both directions.

ex: fish

Concave anterior, convex posterior.

ex: Anurans (frogs)

Concave posterior, convex anterior.

ex: Anurans (frogs)

Prevent rotation around long axis. Saddle-shaped.

Great lateral and vertical flexion.

ex: turtles and birds (cervicles)

Ligaments that join rims of adjacent centra.

Controls stiffness of column and when flexes.

Determines the degree of lateral flexion.

Project from the centra and the arches.

Anti-twist, interlocking pieces.

2 regions:

1) Trunk 2) Caudal

Doesn't support weight.

4 regions:

1) Trunk 2) Caudal 3) Cervical 4) Sacral

Receives and transmits force of muscle movement.

Neck.

Lose connection between pelvic girdle and skull.

Greater freedom of head rotation.

Less jarring when walking.

5 regions:

1) trunk 2) caudal 3) cervical 4) sacral 5) Lumbar (loss of ribs)

ribs decreases, crowding decreases, locomotion increases.

Struts from the VC that fuse and articulate with the vertebrae.

Functions:

muscle attachment site.

help suspend the body.

Protection/rib cabe.

breathing.

form as cartilage within myosepta between blocks of muscles (myomeres).

2 points of articulation with the vert.

fish have two sets (D/V)

Tetrapods have one set (Dorsal)

True Ribs

False Ribs

Floating Ribs

Site of attachment of pelvic girdle to VC.

Direct transfer of prop. force of hindlimbs to axial skeleton.

Midventral; ventral side of the rib cage.

Site of muscle attachment.

Ventilation (b.c part of rib cage).

Forms within ventral connective tissue septum from cartilage.

Abdomial Ribs.

Dermal origin.

Ventral body wall, b/t sternum and pelvis.

Don't articulate with vertebrae with vertebrae.

Support viscera and abdomen.

Site of muscle attachment.

Found in lizards and crocs.