How do a mouse’s insides look? - briefly
A mouse’s internal anatomy comprises a skull encasing the brain, a thoracic cavity containing a four‑chambered heart and paired lungs, a digestive tract extending from esophagus through a modest stomach to a colon, and a musculoskeletal framework of vertebrae and limb bones. Major organs such as the liver, kidneys, and reproductive structures are proportionally similar to those of other small rodents.
How do a mouse’s insides look? - in detail
The internal anatomy of a laboratory mouse occupies a compact volume of roughly 2 cm³, arranged in a linear fashion from head to tail to maximize efficiency within the limited body cavity.
The digestive tract begins with a small oral cavity equipped with incisors and molars for gnawing. Food passes through a short esophagus into a single-chambered stomach surrounded by a dense muscular wall. The small intestine, extending approximately 30 cm, comprises duodenum, jejunum, and ileum, each lined with villi for nutrient absorption. A prominent cecum follows, serving as a fermentation chamber for fibrous material. The large intestine, including colon and rectum, reabsorbs water and forms feces, terminating at the anus.
Air enters via nostrils, travels through the nasal cavity, and proceeds down the trachea to a pair of lobulated lungs. Alveolar sacs provide a large surface area for gas exchange, supported by a thin pleural membrane.
The circulatory system features a four-chambered heart positioned centrally, pumping oxygenated blood from the lungs to systemic circulation and returning deoxygenated blood to the pulmonary circuit. A network of arteries, veins, and capillaries distributes nutrients and removes waste.
Renal function is performed by two bean‑shaped kidneys located dorsally; each kidney filters blood to produce urine, which collects in the urinary bladder before excretion through the urethra.
Reproductive organs differ by sex. In males, paired testes reside within the abdominal cavity, connected to the epididymis and vas deferens. In females, ovaries lie near the kidneys, releasing ova into the oviducts that converge on a bicornuate uterus, ending in a vaginal opening.
The central nervous system comprises a brain weighing approximately 0.4 g, protected by a skull, and a spinal cord extending the length of the vertebral column. Peripheral nerves innervate all major organ systems, coordinating reflexes and voluntary actions.
The musculoskeletal framework includes a skull, vertebral column, rib cage, and limb bones. Muscles attach to skeletal elements via tendons, enabling locomotion, grooming, and feeding behaviors.