Medical illustration of the heart. (c) Duval

Medical illustration of a bone, with a close-up to show the structure of the bone tissue. (c) Duval

Illustration of a baby's skull, brain, and spinal cord, showing normal cerebrospinal fluid (CSF) circulation. CSF serves as a shock absorber and also serves to maintain uniform pressure within the brain and spinal cord.

Illustration of an adult's head in profile, showing the brain and one of the carotid arteries. The carotid arteries supply the head and brain with oxygen-rich blood from the heart.

Illustration of the normal alveolar blood supply.

Illustration of the normal lung and alveolar blood supply.

Medical illustration of a forceps delivery of a baby.

Illustration of a baby's head and neck, showing some internal structures. The outline of the brain, the spinal cord, the upper vertebral column, and the trachea are visible.

Illustration of a transparent normal brain, showing subcortical structures.

Medical illustration of healthy sinuses.

Medical illustration of a healthy respiratory system.

Transparent plastic female medical figure, back view, showing the spinal column and ribs.

Medical illustration of the thymus and heart, with veins and arteries, superimposed on the body of a young girl.

Illustration of a transparent glass woman, showing the ovaries, fallopian tubes, uterus, cervix, and vagina.

Medical illustration of the blood supply to the large intestine, showing the abdominal aorta, superior and inferior mesenteric arteries, and colic arteries. Parts of the large intestine shown include the vermiform appendix, cecum, hepatic flexure, splenic flexure, sigmoid colon, rectum, and anal canal.

Medical illustration showing the liver, gallbladder, duodenum, pancreas, spleen, cystic duct, hepatic duct, common bile duct, and pancreatic duct.

Medical illustration of the upper respiratory tract, midsagittal section, including the three regions of the pharynx. Shown are the nasal conchae, auditory tube opening, hard and soft palates, uvula, pharyngeal tonsil, palatine and lingual tonsils, epiglottis, hyoid bone, vocal cords, trachea, and esophagus.

Medical illustration of a lateral view of the lumbosacral region of the spine. Shown are the third, fourth, and fifth lumbar vertebrae, intervertebral disks, spinal nerves, and upper portion of the sacrum and iliac crest.

Front view of the human figure, muscles dominate the left, and then gradually lighten to reveal only bones on the right.

Medical illustration showing ten-week old fetus in womb.