Illustration of bacterial meningitis, showing the anatomical orientation of the meninges (membranes) that cover the brain (left); normal meninges: dura, arachnoid, and pia mater (top detail); brain with meningitis: infected and inflamed brain and meninges (bottom detail).

Illustration of spinal meningitis: anatomical orientation of the spinal cord within the neck (left); normal meningeal layers covering the spinal cord and nerve roots (center); infected and inflamed meningeal layers due to meningitis (right).

Illustration of fulminant bacterial meningitis in a child, showing infected and inflamed meninges covering the brain. Bacterial meningitis is the most deadly type of meningitis, particularly among infants.

Illustration of spinal meningitis: infected and inflamed meninges (membranes) covering the spinal cord and nerve roots.

Illustration of spinal meningitis: infected and inflamed meninges (membranes) covering the spinal cord and nerve roots.

Illustration of type 2 diabetes, also called non-insulin dependent diabetes, obesity-related diabetes, and adult-onset diabetes. In type 2 diabetes, the body fails to properly utilize the insulin produced by the pancreas, leading to excess glucose in the bloodstream (high blood sugar).

Illustration of type 1 diabetes, also called insulin-dependent diabetes. In type 1 diabetes, the pancreas fails to produce enough (or any) insulin, leading to excess glucose in the bloodstream (high blood sugar).

Illustration of diabetes type 1 and type 2. The actions of normal insulin production and the body's management of glucose levels in the blood (top) is compared and contrasted with those of type 1 (center) and type 2 diabetes (bottom) patients.

Illustration of a spinal cord covered in plaques due to multiple sclerosis (right), compared to a normal spinal cord (left) in situ at the base of the brain.

Illustration of a sprained ankle. The inset shows a torn talofibular ligament, which joins the talus on the foot to the fibula on the lower leg.

Illustration of an obese male, frontal view.

Illustration showing the pathway of a pulmonary embolism (blood clot) from the lower leg to the lungs, frontal view.

Illustration of a male figure performing a surface electromyogram (EMG) shoulder reaching test, rear view, with a graphic chart of the EMG data. An EMG measures the electrical action in muscles.

Illustration showing a penile implant of the pelvis, penis, and testicles, cutaway view. This device is used as the surgical treatment for male impotence, or erectile dysfunction.

Illustration of a blood pressure cuff (sphygmomanometer) on a figure, showing the internal anatomy: heart, aorta, vena cava, kidneys, and urinary bladder.

Illustration series of heart surgery repair, showing a blocked coronary artery with balloon angioplasty. The three cutaway views of a blocked, atherosclerotic coronary artery show: the tunica intima partially detached from the wall of the artery (top); a deflated angioplasty balloon inserted into the artery (middle); and the balloon inflated (bottom).

Illustration of mechanism of traumatic brain injury (TBI) due to whiplash, or coup-contrecoup.

Illustration of an intraoperative view into the open abdomen after removal of the uterus during an abdominal hysterectomy.

Illustration of chondromalacia, or arthritic degeneration of the knee joint cartilage, on the femur. Visible are the medial femoral condyle cartilage with extensive chondromalacia tears, as well as a portion of the inside of the patella showing similar arthritic changes.

Illustration of an embryo at four weeks in utero, cutaway view of the uterus and chorion to show the amniotic sac. The embryo measures 4.0 mm CR (crown-rump) length. The upper limb buds are flipper-like and the lower limb buds have begun to form. Also shown are the lens placodes (primitive eyes), heart prominence, and four pairs of gill arches. (1 of 9)