1. Holes in the two outer layers of a tooth called the enamel and the dentin.

The enamel is the outermost white hard surface and the dentin is the yellow layer just beneath enamel. Both layers serve to protect the inner living tooth tissue called the pulp, where blood vessels and nerves reside.

Small cavities may not cause pain, and may be unnoticed by the patient. Larger cavities can collect food, and the inner pulp of the affected tooth can become irritated by bacterial toxins, foods that are cold, hot, sour, or sweet; therefore, causing toothache. Also referred to as caries.

1. The space between the stomach area and the spine which contains a number of crucial organs: The abdominal cavity includes the lower part of the esophagus, the stomach, small intestine, colon, rectum, liver, gallbladder, pancreas, spleen, kidneys, adrenal glands, ureters, bladder, as well as associated tissues and blood and lymphatic vessels all of which are surrounded by the flat band of fibrous tissue below the skin that covers the underlying tissues and separates the different layers of tissue.
2. Etymology: from Latin abdomen, abdominis, "belly" and from medical Latin abdominalis.

1. The large hollow space between the diaphragm and the groin: In the abdominopelvic cavity there is no structurally distinct separation between the abdomen and pelvic regions.

2. The largest hollow space of the body between the diaphragm and the top of the pelvic cavity and surrounded by the spine and the abdominal muscles and others: The abdominopelvic cavity contains most of the alimentary canal, the liver and pancreas, the spleen, the kidneys, and the adrenal glands. It is lined by the peritoneum, a membrane covering the cavity's inside wall, the parietal peritoneum, and each organ or structure in it, the visceral peritoneum.

The hollow spaces under the arms of people where they are joined to the shoulder: When Tim was studying basic anatomy in his high school, he learned that axillary cavities are medical terms for the armpits.

There are two major body cavities: the dorsal cavity and the ventral cavity, which are spaces within the body that contain and protect internal organs.

These two cavities are defined in their alphabetical positions in this unit.

The area between the inside of the cheek, the teeth, and the gums.

1. Located within the skull where it surrounds and protects the brain.
2. Etymology: cranial comes from Modern Latin cranium which came from Greek kranion, "skull"; while cavity is from Middle French cavité (13th century), from Late Latin cavitas, "hollowness" which came from Latin cavus, "hollow".

Located along the back of the body and head.

It contains organs of the nervous system that coordinate body functions and is divided into two parts: the cranial cavity and the spinal cavity; both of which are defined in this unit.

1. Part of the ventral cavity that is formed by the hip bones and which primarily contains the organs of the reproductive and excretory systems.
2. Etymology: pelvic refers to the "basin-like cavity formed by the bones of the pelvic girdle" from Modern Latin which came from Latin pelvis, "basin, laver" (borrowing of Latin lavare, "to wash").

1. A cavity located within the spinal column and that surrounds and protects the spinal cord.
2. Etymology: from Late Latin spinalis, which came from Latin spina, "back bone" and cavity is from Middle French cavité (13th century), from Late Latin cavitas, "hollowness" which came from Latin cavus, "hollow".

Located along the front of the body; it includes, the thoracic cavity, the abdominal cavity, and the pelvic cavity.

All of these terms are defined separately in their alphabetical positions in this unit.