Snake Myths: Snakes dislocate their jaws to eat large meals

“Dislocation” specifically refers to a bone being out of it’s articulated position.  When you dislocate your shoulder, for example, the ball joint of your upper arm (humerus) has fallen out your shoulder’s socket, often causing damage to ligaments and considerable pain.

When a snake consumes a large prey item, on the other hand, no bones are ever out of position or dislocated, thanks to some key anatomical innovations.  Unlike us, as snake’s lower jaw is split into two independent segments.  This allows the snake to stretch their lower jaws widely apart to accommodate huge meals, but the real magic happens with an incredibly flexible Quadrate Bone.

All four-limbed animals have a quadrate, but it has been adapted to serve various purposes in different animals.  In humans and mammals, for example, the quadrate bone has been adapted to become a part of our inner-ear,  specifically, the hammer (mallues) which, with the anvil (incus), connects our eardrum to our inner ear, allowing us to perceive airborne sounds.  In snakes, however, the quadrate bone connects the lower jaw to the skull via flexible ligaments that give them an immense range to movement, allowing them to swing their jaws nearly 180 degree wide, encompassing almost any sized meal.

Like us, a snake’s quadrate bone is also connected to a snake’s inner ear and instrumental in hearing.  Snakes lack outer ears and eardrums, so they can’t hear the broad range of airborne sounds that we can, but they are sensitive to low-frequency sounds.  By placing their head on the ground, they are able to perceive low-frequency sound of a rodent’s footstep, for example, through their lower jaw via their quadrate bone.  This helps them hone in on potential prey & warn them of approaching threats,

While a snake’s unique skull is incredibly flexible and versatile, no bones actually get dislocated in the process.  Their mouths are just really, REALLY stretchy!

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