Body Cavities Diagram
The body’s organs sit in fluid-lined spaces called body cavities. The dorsal cavity protects the brain and spinal cord; the ventral cavity holds the heart, lungs and digestive organs.
| Main cavity | Cavity | Organs inside |
|---|---|---|
| Dorsal | Cranial cavity | الدماغ |
| Dorsal | Vertebral (spinal) canal | Spinal cord |
| Ventral | Thoracic cavity: pleural cavities (×2) | الرئتان |
| Ventral | Thoracic cavity: mediastinum, incl. pericardial cavity | Heart, oesophagus, trachea, thymus, great vessels |
| Ventral | Abdominal cavity | Stomach, liver, gallbladder, spleen, pancreas, small intestine, most of the large intestine, kidneys (behind the lining) |
| Ventral | Pelvic cavity | Bladder, rectum, internal reproductive organs (uterus, ovaries / prostate) |
How to remember the body cavities
- Split the body into back (dorsal) and front (ventral).
- Dorsal = nervous system: cranial cavity (brain) running into the vertebral canal (spinal cord).
- Ventral, above the diaphragm = thoracic: two pleural cavities (lungs) and the mediastinum with the pericardial cavity (heart).
- Ventral, below the diaphragm = abdominopelvic: abdominal cavity (digestive organs) above the pelvic cavity (bladder, reproductive organs).
Worked example
Which cavity is the appendix in? It hangs off the large intestine in the lower right of the abdomen, below the diaphragm and in front of the spine, so it is in the ventral → abdominopelvic → abdominal cavity (its lower right quadrant). That is why appendicitis pain is felt low on the right of the abdomen.
See the heart inside its pericardial cavity in the heart diagram and the 3D القلب & الدورة الدموية model, or zoom in to the cells those organs are made of.
الأسئلة الشائعة
What are the main body cavities?
Two main ones: the dorsal cavity at the back (cranial cavity + vertebral canal) and the ventral cavity at the front (thoracic cavity + abdominopelvic cavity), separated by the diaphragm.
What separates the thoracic and abdominal cavities?
The diaphragm, a dome-shaped sheet of muscle. It is also the main breathing muscle: when it contracts it flattens and pulls air into the lungs.
What is the abdominopelvic cavity?
The abdominal and pelvic cavities together. No wall divides them; an imaginary line across the top of the pelvis marks where one ends and the other begins.
What is the mediastinum?
The middle part of the thoracic cavity, between the two pleural cavities. It holds the heart (inside the pericardial cavity), the trachea, oesophagus and the large blood vessels.
