How do a snake’s ribs and vertebrae help it move?

Snakes rely on their highly specialized vertebral column and ribs to achieve the flexibility and structural support necessary for movement.

Vertebrae

The snake's skeleton is exceptionally elongated, containing between 100 and 450 body vertebrae. These bones articulate at five distinct points, including unique structures called zygosphenes and zygantra. This complex arrangement allows for significant lateral and vertical rotation while maintaining enough rigidity to support the body, effectively preventing unwanted twisting of the column.1

Ribs and Locomotion

A pair of ribs is associated with nearly every body vertebra. These ribs are essential for various forms of movement, particularly in rectilinear locomotion. In this pattern, the snake keeps its body relatively straight and moves forward using its ventral scales. Each scale is connected to ribs by two pairs of muscles. By contracting these muscles in sequence, the snake lifts and pulls its scales, anchoring them against the ground to inch the body forward. Additionally, the overall body shape—such as lateral compression in arboreal species—works with the skeletal frame to provide the necessary rigidity for navigating complex environments like branches.23