Do Mice Have Bones?

Written by Kyle Glatz
Published: July 27, 2022
Image Credit iStock.com/Weber
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Have you ever found mice in your home even though there is no conceivable way they could get in? Well, some species can fit into a hole that is just one-fourth of an inch! That’s smaller than a nickel. So, it’s only fair to ask, do mice have bones? We’re going to explore this question since these small mammals manage to squeeze into impossibly small spaces.

Let’s get to the bottom of this question and explore the anatomy of mice a little better.

Do Mice Have Bones?

baby hamster siblings
Mice have complex skeletons.

iStock.com/Olga Skred

Yes, mice have bones. Although it may seem like they do not because they are so tiny and capable of squeezing their bodies into impossible shapes, mice have a full skeleton. After all, they are vertebrate mammals.

The skeletal system of a mouse has the same purpose as other animals. The bones provide support for the body, protection, and the shape of their bodies. By looking at a mouse, we can see that it has an elongated skull that ends in a snout. 

They have many bones that are similar to humans. They have back vertebrae, scapulae, metatarsals, and more. If you’re wondering, yes: mouse tails have bones, too.

Mice have an intricate skeleton. However, that has led to some myths regarding their bodies. For example, one myth that has persisted for years says that mice have collapsible skeletons, especially skulls. That is not true at all.

The skeleton of a mouse is surrounded by musculature, tendons, and ligaments. It can’t collapse on itself so that it can squeeze under a door a little better. That’s especially true of the skull. The mouse can’t force the bones of its skull to flatten its brain!

How Many Bones Do Mice Have?

Another thing that people want to know about mice is if they have a lot of bones or just a few. As we’ve mentioned, mice tend to have many bones that are analogous to humans. In fact, aside from the bones in their tails, mice have a similar number of bones to humans.

The average mouse has between 225 and 231 bones. That’s more bones than the human body which has 206 bones. However, over 20 of those bones are found in the tail, and that might help explain the disparity.  

As you can see, mice have a lot of bones. Their skeletons are intricate and strong enough to grant them protection and form. Yet, these bones have other qualities that are worth exploring.  

How Do Mice Manage to Squeeze into Small Areas?

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Mice have flexible bones.

iStock.com/Weber

As we’ve said, a pervading myth suggests that mice lack bones because they can squeeze into such tiny spaces. Although mice do not have a collapsible skeleton, their bones do have a quality that makes this possible: flexibility.

Specifically, these mammals have a lot of flexibility in the area between the vertebrae of their backs. Also, their ribs can flex quite a bit. These bones can temporarily flex rather easily. The result is that mice can squeeze themselves through narrow gaps without as much resistance as other mammals. When people see mice exercise their insane flexibility, they believe that they have no bones at all.

So, the only real constraint on places where mice can go lies in their head. Their skull is not flexible. As a result, the mouse can only go into holes and gaps that can fit its head.

Since mice are smaller than rats, they easily get into places. That’s why they’re frequently seen in homes and other areas that humans inhabit. However, rats can still get into some pretty small spaces.

How Small of a Hole Can a Mouse Fit In?

baby mouse closeup
Young mice can fit through a hole the size of pencil.

Adrian Eugen Ciobaniuc/Shutterstock.com

Mice can fit in holes of various sizes throughout their lives. However, as they get older, they can’t fit through the same holes they could have when they were younger.

Nevertheless, studies have shown that young mice can fit through a hole about the width of a pencil or pen. That means if you had a hole that small in your home, a young mouse could get in. Adult mice, while significantly larger, do not lose their ability to squeeze into small spaces.

Almost any adult mouse can squeeze through a hole the size of a quarter. Most of them can squeeze through a hole the size of a nickel, and many of them can squeeze through a hole the size of a dime. The latter usually takes a few moments longer than the rest. However, adult mice are still highly capable of getting into places using small holes.

How to Keep Mice from Getting into Your Home

A family of house mice eating spilled cereal off the floor
Seal food in your home to ensure that mice can’t get inside.

Landshark1/Shutterstock.com

Now that you know how easy it is for mice to get into your house, you probably want to make sure they can’t get in. Follow these steps to make sure you make it more difficult for mice to get into your home.

  1. Regularly check your home for signs of mouse activity like mouse droppings, nests, or scratching.
  2. Remove their attraction to your home by sealing up any food you have, including pet food.
  3. Clean your counters, cabinets, and floors to reduce the crumbs and morsels that they want.
  4. Keep plants to a minimum around your home to reduce cover.
  5. Seal holes in your brick home with cement.
  6. Seal tiny holes in your siding and doorways with caulk.
  7. Make sure you use weather stripping on your doors.
  8. Consider using mouse repellent mixtures, either homemade, like fabric softener sheets, or commercially made ones.
  9. Set up ultrasonic devices around the perimeter of your home.
  10. Set some humane traps to catch and remove the mice.

Each of these methods will help you keep mice from your home and stay on top of any infestations that could be forming.

Now that we’ve settled the question “do mice have bones?” you should understand that mice can be hard to keep out of your house. That doesn’t mean it’s impossible to prevent an infestation, though. With the information we’ve provided, you should know just how big a hole they need to gain access to your home. By acting quickly to seal them up, you can stave off a mice infestation.

Grasshopper Mouse sitting on the ground.
Grasshopper Mouse sitting on the ground.
iStock.com/Weber
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About the Author

I'm a freelance writer with 8 years of experience. I've written in a variety of niches such as video games, animals, and managed service providers. I graduated from Rowan University in 2014 with degrees in English and Education. When I'm not working, I enjoy playing video games, reading, and writing for fun.

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