Body terminology

Anterior (ventral)

Describes the front or direction toward the front of the body.

Posterior (dorsal)

Describes the back or direction toward the back of the body.

Superior (cranial)

Describes a position above or higher than another part of the body.

Inferior (caudal)

Describes a position below or lower than another part of the body; toward the tail or coccyx.

Lateral

Describes the side or direction toward the side of the body.

Medial

Describes the middle or direction toward the middle of the body.

Proximal

Describes a position in a limb that is nearer to the point of attachment or trunk of the body.

Distal

Describes a position in a limb that is farther from the point of attachment or trunk of the body.

Superficial

Describes a position closer to the surface of the body.

Deep

Describes a position farther from the surface of the body.

Sagittal plane

A vertical plane that divides the body or an organ into right and left sides.

Midsagittal (median) plane

A sagittal plane that runs directly down the middle of the body and divides it into equal right and left sides.

Parasagittal plane

A sagittal plane that divides the body into unequal right and left sides.

Frontal plane

A vertical plane that divides the body or an organ into anterior (front) and posterior (rear) portions.

Coronal plane

Another name for the frontal plane.

Transverse plane

A horizontal plane that divides the body or an organ into upper and lower portions.

Cross-section

An image produced by a transverse plane.

Dorsal (posterior) cavity

The large posterior body cavity; includes the cranial and spinal cavities.

Ventral (anterior) cavity

The large anterior body cavity; includes the thoracic and abdominopelvic cavities.

Cranial cavity

The cavity that houses the brain; protected by the skull bones and cerebrospinal fluid.

Spinal (vertebral) cavity

The cavity that encloses the spinal cord; protected by the vertebral column and cerebrospinal fluid.

Cerebrospinal fluid (CSF)

A colorless fluid produced by the brain that cushions the brain and spinal cord within the posterior (dorsal) cavity.

Thoracic cavity

The superior subdivision of the ventral cavity; enclosed by the rib cage and contains the lungs and heart.

Mediastinum

The region within the thoracic cavity where the heart is located.

Diaphragm

A muscular structure that forms the floor of the thoracic cavity and separates it from the abdominopelvic cavity.

Abdominopelvic cavity

The largest body cavity; contains the abdominal and pelvic cavities and their organs.

Abdominal cavity

The portion of the abdominopelvic cavity that houses the digestive organs.

Pelvic cavity

The portion of the abdominopelvic cavity that contains the pelvic and reproductive organs.

Abdominal regions

Anatomical divisions of the abdomen into nine regions used to describe the location of pain, masses, and other structures.

Abdominal quadrants

Anatomical divisions of the abdomen into four quadrants used to describe the location of pain, masses, and other structures.

Tissue membrane

A thin layer or sheet of cells that covers the outside of the body, organs, internal passageways, and movable joint cavities.

Two basic types of tissue membranes

Connective tissue membranes and epithelial membranes.

Connective tissue membrane

A membrane formed solely from connective tissue; encapsulates organs and lines movable joints.

Synovial membrane

A type of connective tissue membrane that lines the cavity of a freely movable joint and produces synovial fluid.

Synovial fluid

Fluid that lubricates freely movable joints and allows smooth movement.

Epithelial membrane

A membrane composed of epithelium attached to a layer of connective tissue.

Mucous membrane (mucosa)

An epithelial membrane that lines body cavities and hollow passageways that open to the external environment.

Mucous membrane locations

Digestive, respiratory, excretory, and reproductive tracts.

Mucus

Substance produced by epithelial exocrine glands that covers the epithelial layer of mucous membranes.

Lamina propria

The underlying connective tissue of a mucous membrane that supports the fragile epithelial layer.

Cutaneous membrane

The epithelial membrane that forms the skin.

Skin (cutaneous membrane)

A stratified squamous epithelial membrane resting on connective tissue; its surface is exposed to the external environment and contains dead, keratinized cells that protect against dehydration and pathogens.

Serous membrane (serosa)

An epithelial membrane composed of mesothelium supported by connective tissue that lines coelomic cavities and covers organs within those cavities.

Mesothelium

The epithelium that forms the lining of serous membranes; derived from mesoderm.

Parietal layer

The layer of a serous membrane that lines the walls of a body cavity.

Visceral layer

The layer of a serous membrane that covers the organs (viscera).

Serous space

The very thin, fluid-filled space between the parietal and visceral layers.

Pleura

The serous membrane surrounding the lungs and lining the pleural cavity; reduces friction between the lungs and body wall.

Pleural cavity

The serous cavity surrounding the lungs.

Pericardium

The serous membrane surrounding the heart in the pericardial cavity; reduces friction between the heart and surrounding structures.

Pericardial cavity

The serous cavity surrounding the heart.

Peritoneum

The serous membrane that surrounds several organs in the abdominopelvic cavity.

Peritoneal cavity

The serous cavity that reduces friction between abdominal and pelvic organs and the body wall.

Three serous membranes

Pleura, pericardium, and peritoneum.

Coelomic cavities

Cavities that do not open to the outside.

Homeostasis

The state of steady internal conditions maintained by living things.

Connective tissue

A type of tissue that holds in place, connects, and integrates the body's organs and systems.

Prone

A face-down orientation.

Supine

A face-up orientation.