What flexible connection lets a snake’s lower jaw halves spread apart while swallowing?

An elastic ligament lets a snake’s lower jaw halves spread apart while swallowing.

Unlike the lower jaws of humans, a snake’s two mandibular bones are not fused rigidly at the front. They are connected by an elastic ligament, allowing the left and right sides to move independently and widen the mouth around large prey. Other skull joints are also highly mobile, but the lower jaw’s flexible connection is especially important.

This arrangement does not mean that snakes dislocate their jaws, a common misconception. They use normal anatomical joints and stretchy connective tissue to expand the gape. Their backward-pointing teeth help hold prey while the jaws advance alternately over it.

Snake swallowing is therefore a coordinated process involving jaw muscles, skull mobility, skin stretch and the flexible body. The animal does not chew; it gradually moves prey toward the throat before digestion begins.