The term “fundus” in anatomy refers to the part of a hollow organ that is furthest from its opening, often forming a rounded or dome-shaped end. This anatomical designation applies across various body systems, from sensory organs to those involved in reproduction and digestion. Understanding the fundus of different organs provides insights into their structure and how they contribute to overall bodily function.
The Eye’s Fundus
The fundus of the eye is the inner, back surface of the eyeball, opposite the lens. This region contains several distinct structures, including the retina, optic disc, macula, fovea, and various blood vessels. The retina, a layer of nerve tissue, covers the back of the eye and contains photoreceptor cells that convert light into electrical signals sent to the brain.
The optic disc is where the optic nerve exits the eye and where retinal blood vessels enter and leave. This area lacks photoreceptors, resulting in a blind spot. Adjacent to the optic disc, the macula is a central retinal area responsible for sharp, detailed central vision and color perception. The fovea, a small depression in the macula, offers the highest visual acuity due to a dense concentration of cone photoreceptor cells. The choroid, situated between the retina and the outer white sclera, provides nutrients to the eye through its network of blood vessels.
The Uterine Fundus
The fundus of the uterus is the dome-shaped, uppermost portion of this organ. It is located opposite the cervix, the lower, narrow part that opens into the vagina. The myometrium, the muscular wall, is particularly prominent in the fundus.
During pregnancy, the uterine fundus expands to accommodate the growing fetus. It plays a role in uterine contractions during labor, as its muscles contract to help push the baby towards the cervix and out of the birth canal. Healthcare providers also use the fundus to measure fundal height, which is the distance from the top of the pubic bone to the top of the uterus. This measurement, taken from around 20 weeks, helps assess fetal growth and gestational age.
Fundus in Other Organs
The term “fundus” also describes regions in several other hollow organs throughout the body. The stomach, for instance, has a fundus, the dome-shaped upper part located above the entrance of the esophagus. This region serves as a temporary storage area for undigested food and accumulated gases from digestion. The gastric fundus also contains glands that secrete digestive juices, including hydrochloric acid and pepsinogen.
Another example is the fundus of the gallbladder, which is the broad, rounded end of this pear-shaped organ. Located beneath the liver, the gallbladder’s fundus is involved in storing and concentrating bile, a digestive fluid produced by the liver that aids in fat digestion. The urinary bladder also features a fundus, referring to its posterior and inferior base, farthest from the bladder neck and urethra. This muscular region of the bladder plays a role in urine storage and contracts to facilitate urine expulsion.
Assessing the Fundus in Healthcare
Examining the fundus of various organs provides valuable diagnostic information in healthcare. For the eye, a procedure called fundoscopy, or ophthalmoscopy, allows health professionals to view the fundus directly. Through fundoscopy, they can detect signs of systemic diseases like diabetes, which may manifest as retinal hemorrhages, microaneurysms, or cotton wool spots. Hypertension can cause changes in retinal blood vessels, while glaucoma may show abnormalities in the optic disc, and macular degeneration affects the macula.
In obstetrics, the measurement of fundal height is a routine screening tool used during prenatal appointments to monitor fetal growth and position. A fundal height measurement that is significantly smaller or larger than expected for the gestational age may prompt further investigation, such as an ultrasound, to assess for conditions like slow fetal growth, multiple pregnancies, or abnormal amniotic fluid levels. Understanding the anatomy of the fundus in organs like the stomach, gallbladder, and bladder assists in diagnosing conditions specific to these areas, such as gastritis, gallstones, or bladder tumors.