How many vertebrae does a mouse have? - briefly
A typical Mus musculus has about 70 vertebrae in total, including roughly 30–40 in the tail. The remaining vertebrae follow the usual mammalian pattern: 7 cervical, 13 thoracic, 6 lumbar, and 4 sacral.
How many vertebrae does a mouse have? - in detail
The mouse vertebral column is divided into five regions.
- Cervical: 7 vertebrae, identical to most mammals.
- Thoracic: 13 vertebrae, each bearing a pair of ribs.
- Lumbar: 6 vertebrae, forming the lower back.
- Sacral: 4 fused vertebrae, constituting the sacrum.
- Caudal (tail): 20 – 25 vertebrae, the exact number depending on strain and individual tail length.
Summing the fixed regions yields 30 vertebrae; adding the variable caudal segment results in a total count of approximately 50 to 55 vertebrae per mouse.
Tail vertebrae exhibit the greatest variability, reflecting genetic differences and developmental factors. In laboratory strains, the caudal count typically clusters around 22, producing an overall total of 52 vertebrae.
These numbers are essential for comparative anatomy, spinal biomechanics research, and the interpretation of skeletal phenotypes in genetic studies.