An antrum is a general term for a cavity or chamber that can be found in different organs or sites in the body. Antra serve a unique and important purpose for each location they belong in. In this article, we will explore some of the most common types of antra and their functions.

There are two different antra that exist in or near the stomach. The first is the antrum cardiacum, which is the dilation that occurs low in the esophagus, close to where it flows into the stomach. The second is the pyloric antrum, which is also commonly known as the gastric antrum. This is the wider part of the pylorus, which is the narrower part of the stomach. It resides upstream from the pyloric canal and its junction of the pyloric sphincter to the duodenum, or first part of the small intestine.

The gastric antrum contains mucus-secreting cells and gastrin-secreting endocrine cells. Gastrin is a hormone that stimulates acid secretion and gastric motility. The gastric antrum can be affected by various medical conditions, such as gastritis and peptic ulcers. Gastritis is inflammation of the stomach lining, which can cause symptoms like nausea, vomiting, stomach cramps, and indigestion. Peptic ulcers are sores that develop along the lining of the stomach or duodenum, which can cause burning or gnawing abdominal pain.

The mastoid antrum is a cavity in the temporal bone near the middle ear. This air-filled antrum is next to mastoid air cells, which are small spaces within the mastoid process of the temporal bone. The mastoid antrum communicates with the middle ear through a narrow opening called the aditus. The mastoid cells are thought to affect the function of the inner and middle ear by regulating air pressure and temperature.

The mastoid antrum can be involved in infections or inflammations of the middle ear, such as otitis media or mastoiditis. Otitis media is a common condition that occurs when fluid builds up behind the eardrum, causing pain, fever, hearing loss, and sometimes discharge from the ear. Mastoiditis is a rare but serious complication of otitis media that occurs when bacteria spread from the middle ear to the mastoid bone, causing swelling, redness, tenderness, and pus formation.

Follicular antra are cavities within the ovarian follicles that contain fluid and an immature egg cell. Ovarian follicles are structures that develop in the ovaries during each menstrual cycle and release an egg during ovulation. Follicular antra begin to form when follicles reach a certain size and stage of development.

The number and size of follicular antra can be measured by ultrasound as an indicator of ovarian reserve, which is a woman’s potential to conceive. The higher the number of follicular antra, also known as antral follicle count (AFC), the greater probability of pregnancy. AFC can be used as part of fertility testing or treatment planning for women who have difficulty getting pregnant.

The maxillary antrum is the largest of the paranasal sinuses, which are air-filled spaces within the bones of the face that communicate with the nasal cavity. The maxillary antrum is also known as the maxillary sinus, or sometimes as
the antrum of Highmore. It is located within
the maxillary bone next to
the nose, above
the teeth,
and under
the eyes.