Anatomy Essentials: Body Planes, Cavities, and Regions
Learn structural body organization including sagittal and frontal planes, dorsal and ventral cavities, and the 9 abdominopelvic regions for medical study.
Anatomical Terminology: Planes, Cavities, and Regions
An Overview of Structural Body Organization
Major Body Planes
Sagittal Plane: Divides the body vertically into right and left parts (Midsagittal lies exactly on the midline).
Frontal (Coronal) Plane: Divides the body vertically into anterior (front) and posterior (back) parts.
Transverse (Horizontal) Plane: Divides the body horizontally into superior (upper) and inferior (lower) parts.
Dorsal Body Cavity
Protects the fragile nervous system organs and is located toward the back of the body.
Cranial Cavity: Encases the brain inside the skull.
Vertebral (Spinal) Cavity: Runs within the vertebral column and encloses the delicate spinal cord.
Ventral Cavity: Thoracic
The superior subdivision of the ventral cavity, surrounded by the ribs and chest muscles.
Pleural Cavities: Lateral cavities each enveloping a lung.
Mediastinum: Central region containing the pericardial cavity and other thoracic organs (esophagus, trachea).
Ventral Cavity: Abdominopelvic
Separated from the thoracic cavity by the diaphragm, this cavity has two continuous parts.
Abdominal Cavity: Superior portion containing the stomach, intestines, spleen, and liver.
Pelvic Cavity: Inferior portion lying in the bony pelvis; contains the urinary bladder, reproductive organs, and rectum.
Ventral Cavity Membranes
Walls of the ventral body cavity and organ surfaces are covered by a thin, double-layered membrane called the serosa.
Parietal Serosa: Lines the cavity walls. Visceral Serosa: Covers the organs. Serous Fluid: Lubricates space between layers.
Examples: Pleura (lungs), Pericardium (heart), Peritoneum (abdominopelvic cavity).
Abdominopelvic Regions (9 Divisions)
Upper: Right Hypochondriac, Epigastric, Left Hypochondriac.
Middle: Right Lumbar, Umbilical, Left Lumbar.
Lower: Right Iliac (Inguinal), Hypogastric (Pubic), Left Iliac (Inguinal).
Organs by Region
Epigastric: Stomach. Umbilical: Small intestine surrounding navel.
Right Hypochondriac: Liver gallbladder. Left Hypochondriac: Diaphragm, spleen.
Hypogastric: Urinary bladder. Iliac Regions: Cecum (Right), Initial sigmoid colon (Left).
Abdominal Quadrants
A simpler 4-part division often used by medical personnel to locate pain or tumors.
1. Right Upper Quadrant (RUQ) 2. Left Upper Quadrant (LUQ) 3. Right Lower Quadrant (RLQ) 4. Left Lower Quadrant (LLQ)
Other Body Cavities
Oral & Digestive: Mouth through rectum. Nasal: Within the nose. Orbital: Houses the eyes. Middle Ear: Contains ossicles.
Synovial Cavities: Joint spaces enclosed within fibrous capsules surrounding freely movable joints (e.g., knee, elbow).
- anatomy
- medical-terminology
- body-planes
- body-cavities
- abdominopelvic-regions
- biology
- human-anatomy
- anatomical-position