How many vertebrae do rats have? - briefly
Rats have roughly 53 vertebrae, comprising 7 cervical, 13 thoracic, 6 lumbar, 4 fused sacral and about 23 caudal segments. This count varies slightly among individuals but remains within that range.
How many vertebrae do rats have? - in detail
Rats possess a segmented axial skeleton that can be divided into cervical, thoracic, lumbar, sacral and caudal regions.
The cervical region consists of seven vertebrae, identical to most mammals.
The thoracic region contains thirteen vertebrae, each bearing a pair of ribs that support the rib cage.
The lumbar region comprises six vertebrae, providing flexibility and bearing the weight of the abdominal cavity.
The sacral region is formed by four fused vertebrae that create a solid sacrum, articulating with the pelvis.
The caudal region, forming the tail, varies in number among individuals; typical laboratory rats have between twenty and twenty‑five caudal vertebrae.
Summing the standard counts (7 cervical + 13 thoracic + 6 lumbar + 4 sacral) yields thirty‑one vertebrae before the tail. Adding the average caudal count (≈ 22) results in an approximate total of fifty‑three vertebrae.
Variability in the caudal segment reflects genetic background, age and sex, with some strains exhibiting up to twenty‑seven caudal vertebrae.
The vertebral formula for a typical rat can therefore be expressed as 7‑13‑6‑4‑(20‑25), indicating the range of possible total vertebrae from fifty‑one to fifty‑seven.
Understanding this vertebral arrangement aids in comparative anatomy, surgical planning and the interpretation of radiographic studies.