Anatomical Directions, Planes and Major Body Cavities

Anatomical Directions and Terms

• Anterior (ventral): Toward the front of the body.
• Posterior (dorsal): Toward the back of the body.
• Superior: A part above another part.
• Inferior: A part below another part.
• Medial: Toward the midline (median plane) of the body.
• Lateral: Away from the midline of the body; toward the sides.
• Proximal: Toward the point of attachment to the body.
• Distal: Away from the point of attachment to the body.
• Deep: Toward the inside of the body.
• Superficial: Toward the outside of the body.
• Parietal: A membrane that covers an internal body wall.
• Visceral: A membrane that covers an organ.

Body Planes

Sagittal: The plane that runs down through the body, dividing it into left and right portions. Subsections of the sagittal plane include: Midsagittal: Runs through the median plane and divides the body along the line of symmetry into equal left and right halves. Parasagittal: Parallel to the midline but does not divide the body into equal left and right portions. Frontal (coronal): The plane that runs perpendicular to the sagittal plane and divides the body into anterior (front) and posterior (back) portions.

Transverse: A horizontal plane that divides the body into upper and lower portions; also called a cross-section.

Body Cavities and Subdivisions

Dorsal cavity: Bones of the cranial portion of the skull and the vertebral column, toward the posterior (dorsal) side of the body.

Cranial cavity: Contains the brain.

Spinal cavity: Contains the spinal cord, which is an extension of the brain.

Ventral cavity: The anterior portion of the torso; divided by the diaphragm into the thoracic cavity and the abdominopelvic cavity.

Thoracic cavity: The chest; contains the trachea, bronchi, lungs, esophagus, heart and great blood vessels, thymus gland, lymph nodes, and nerves, as well as the following smaller cavities:

• Pleural cavities: Surround each lung.
• Pericardial cavity: Contains the heart. The pleural cavities flank the pericardial cavity.

Abdominopelvic cavity: An imaginary line running across the hipbones divides the body into the abdominal and pelvic cavities.

Abdominal cavity: Contains the stomach, liver, gallbladder, pancreas, spleen, small intestines, and most of the large intestine.

Pelvic cavity: Contains the end of the large intestine, rectum, urinary bladder, and internal reproductive organs.