How many limbs does a mouse have? - briefly
A mouse has four limbs: two forelimbs and two hindlimbs.
How many limbs does a mouse have? - in detail
Mice, like all placental mammals, possess four paired appendages. The anterior pair consists of forelimbs that terminate in five digits, each equipped with claws for grasping and climbing. The posterior pair comprises hindlimbs, also ending in five digits, adapted for locomotion, digging, and balance.
- Forelimb structure: humerus, radius, ulna, carpals, metacarpals, phalanges (five per limb).
- Hindlimb structure: femur, tibia, fibula, tarsals, metatarsals, phalanges (five per limb).
Muscle groups differ between the two sets: the forelimbs contain flexor and extensor muscles specialized for fine motor tasks, while the hindlimbs feature larger extensors that generate propulsive force during rapid sprints. Developmentally, limb buds appear at embryonic day 9.5, with patterning governed by the Sonic hedgehog (Shh) and Fibroblast growth factor (FGF) signaling pathways, establishing the characteristic tetrapod arrangement.
Comparative anatomy shows that this quadrupedal layout is conserved across rodents, providing stability, agility, and the ability to navigate complex burrow systems. Any deviation from the standard four‑limb plan, such as polydactyly, is a rare genetic anomaly and not representative of the species.