Human Fetus in the Womb at 21 Weeks (Black Skin)

Description

The fetus lies in the characteristic flexed attitude of the second trimester, seen from behind and to the side, with the large domed cranium dominating the body proportions and the well-modelled auricle of the external ear clearly formed against the temporal region. The upper limbs are folded across the chest so that the forearm crosses in front of the thorax and the fingers, each with distinct digits and forming nail beds, lie near the face; the lower limbs are drawn up so that the thigh and foot rest against the trunk. The umbilical cord loops from the abdomen, its coiled course revealing the two umbilical arteries and the single, wider umbilical vein spiralling within Wharton's jelly. Behind the fetus the vascularised uterine wall and the villous placental surface enclose the amniotic space. Twenty-one weeks sits within the window when detailed second-trimester ultrasound is performed, and the features shown here correspond to the structures a sonographer surveys: cranial contour and biparietal diameter, limb and digit counts, femur length, and the number of vessels within the cord. A two-artery, one-vein cord is the normal finding, and this rendering provides the reference against which single umbilical artery is recognised. Fetal position, cord looping and the relationship of the cord insertion to the placental surface are also central to counselling on nuchal loops, cord accidents and placental function, while the degree of limb flexion illustrates the tone expected at this stage. The image suits obstetric and midwifery teaching on second-trimester fetal development, embryology and antenatal care lectures, and week-by-week pregnancy atlases and applications. It works equally well in patient-facing material for anomaly-scan counselling and in publication figures on fetal growth, umbilical cord anatomy and uteroplacental relationships, and forms part of a matched series spanning weeks 20 to 22. Anatomical accuracy verified by SciePro's Medical Advisory Board.