Illustration of the lower gastrointestinal (GI) tract with McBurney's point. McBurney's point is the point over the abdomen that is one-third the distance from the anterior superior iliac spine (ASIS), or anterior iliac crest, to the umbilicus. Patients with acute appendicitis usually have tenderness at this point.

Illustration of Barrett's esophagus, with orientation to the gastrointestinal system. A sectioned esophagus (inset) is shown presenting characteristics of Barrett's esophagus, a condition that results from chronic gastrointestinal reflux disease (GERD) or esophagitis. Normal squamous cells that line the esophagus change to specialized columnar cells.

Illustration of an inflamed appendix (appendicitis). The background image shows the GI tract and McBurney's point, the area clinicians use to palpate and diagnose appendicitis.

Typical location of endometrial fibroids and treatment options. The syringe indicates injectable synthetic hormones such as GnRH analogs. Hysteroscopic myomectomy is the removal of fibroids inside the uterus. Laparoscopic myomyectomy removes fibroids outside the uterus. Fibroid embolization uses tiny polyvinyl particles to block arteries feeding the fibroid.

Illustration showing lower back pain. This rendering includes the lower back muscles and a phantom image of the spine.

Illustration of lower back pain. A 3D composite in the foreground shows the neurotransmitter release associated with pain. The background rendering includes the lower back muscles and a phantom image of the spine.

Illustration montage showing possible sources of chest pain. These sources include cardiovascular, respiratory, and gestroesophageal conditions, as well as muscle strain.

Illustration of typical ulnar deviation of the fingers. The inset image shows an inflamed joint. The hand and joint are affected by rheumatoid arthritis.

Illustration of a sectioned gallbladder with gallstones of typical size and shape. This depiction also shows the usual site of entrapment for a large stone; it blocks the cystic duct.

Illustration showing the anatomical orientation of the liver, gallbladder, and GI tract. The inset image shows a sectioned gallbladder with gallstones of typical size and shape. This depiction also reveals the usual site of entrapment for a large stone; it blocks the cystic duct.

Illustration showing the anatomical orientation of the liver, gallbladder and lower GI tract.

Illustration of the major arteries of the lower limbs, schematically shown in a pair of legs and feet.

Illustration of the major arteries of the lower limbs, schematically shown in a pair of legs and feet.

Illustration of the connection between the brain and penis. Shown is the connection between the cortex and hypothalamus of the brain and the nerves supplying the penis that are related to erectile function. An enlarged inset shows the nerve fibers located between the cavernous sinuses of the erectile tissue, which are filled with blood.

Illustration of the primary components of the human digestive system, including the esophagus, stomach, liver, gallbladder, pancreas, small intestine, large intestine, appendix, and rectum. The stomach and small and large intestines are shown with partial cutaway views to reveal internal details.

Illustration of the primary components of the human digestive system, including the esophagus, stomach, liver, gallbladder and bile ducts, small intestine, large intestine, appendix, and rectum.

Illustration of gingivitis, showing an inflamed gingiva (gum) on the right side of the tooth. For comparative purposes, a normal gingiva is shown on the left side of the tooth.

Illustration of the front view of a human pancreas.

Illustration of the front view of a human pancreas.

Illustration of a normal pancreatic islet of Langerhans. Cells from the glandular tissue of the pancreas are shown, with an islet (center) made up of the smaller endocrine cells that are responsible for insulin production.