Illustration of a fetus at nine weeks in utero, cutaway view of the uterus and chorion to show the amniotic sac and fetal development. The lumbar spine, pelvic bones, and pubic symphysis are also shown within the figure. (2 of 9)

Illustration of a fetus at twelve weeks (third month) in utero, cutaway view. The lumbar spine, pelvic bones, and pubic symphysis are also shown within the figure. (3 of 9)

Illustration the process that causes heartburn (acid reflux or pyrosis), cutaway view. The stomach is partially contracted, with yellow fluid containing stomach acids traveling into the esophagus. Blue arrows show the direction of movement of the yellow fluid.

Illustration of spinal fusion surgery (arthrodesis), showing an anterior cervical (neck) fusion plate and screws. This iamge shows the placement of an Orion fixation plate in a standard fusion of the anterior cervical spine.

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

Illustration of a Schwann-Ganz catheter placed into a subclavian vein of a woman. The catheter extends through the superior vena cava and into the heart, and is used to measure hemodynamics during open heart surgery, particular pulmonary capillary pressure (PCP). The thoracic organs, abdominal organs, and major blood vessels are also shown.

Illustrations of three variations in birth presentation (position) for a 28 week old fetus. The first illustration shows a longitudinal lie in a vertex position; the second is a longitudinal lie in a breech position; the third image shows a transverse lie in a vertex position.

Illustration of labor and delivery: axis of the fetal shoulders in relation to the maternal pelvis. The fetus is crowning through mother's birth canal.

Illustration of labor and delivery: manipulative delivery of the posterior fetal arm.

Illustration of labor and delivery, showing the Woods (corkscrew) maneuver. The fetus is crowning through mother's birth canal, and the attendant is turning the fetus from behind the shoulder.

Illustration of spinal cord compression and herniation of C6-C7 intervertebral disc. The inset shows the anatomical position within the neck.

Illustration comparing normal skin and skin with a second degree burn injury.

Illustration of shoulder surgery, showing an open Mumford surgical procedure being performed on the distal clavicle. The left image shows the exposure of the clavicle. The right image shows the excision of the distal clavicle.

Illustration of a gastrostomy feeding tube in place within the stomach of a female figure, left sagittal view.

Illustration of the stages of birth presentation for a fetus. The fetus is shown in an anterior presentation at the +2 station. Labeled anatomical structures include the uterus, placenta, pubic symphysis and sacrum. Also labeled are the various stages of presentation (-3, -2, -1, 0, +1, +2, +3).

Illustration of the stages of birth presentation for a fetus. The fetus is shown in an anterior presentation at the +1 station. Labeled anatomical structures include the uterus, placenta, pubic symphysis and sacrum. Also labeled are the various stages of presentation (-3, -2, -1, 0, +1, +2, +3).

Illustration of thoracic outlet syndrome (TOS), a compression of nerves and blood vessels in the upper thorax (chest). The normal passage of the brachial plexus through the thoracic outlet is shown on the right side of the torso. The brachial plexus is shown pinched between the scalene muscles on the left side, resulting in thoracic outlet syndrome.

Illustration of the fetal head positions (stations of descent) during childbirth. The fetus is shown in an asymmetrical combination of descent station scales (-3, 0, +5); normal stations are either -5, 0, +5 or more commonly -3, 0, +3.

Illustration of umbilical cord prolapse, showing delivery of the fetus with the aid of a vacuum extractor (ventouse). Umbilical cord prolapse occurs when the umbilical cord precedes the fetus out of the uterus. In this case, a loop of the umbilical cord is caught between the vaginal wall and the fetal head, leading to diminished blood and oxygen supplies.

Illustration of umbilical cord prolapse during childbirth. Umbilical cord prolapse occurs when the umbilical cord precedes the fetus out of the uterus. In this case, a loop of the umbilical cord is caught between the vaginal wall and the fetal head, leading to diminished blood and oxygen supplies.