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Macrocephaly is a condition in which circumference of the human head is abnormally large. [1] It may be pathological or harmless, and can be a familial genetic characteristic. . People diagnosed with macrocephaly will receive further medical tests to determine whether the syndrome is accompanied by particular disorde
The human head typically weighs between 2.3 and 5 kilograms (5.1 and 11.0 lb) Over 98% of humans fit into this range. There have been odd incidences where human beings have abnormally small or large heads.
A human baby's brain at birth averages 369 cm 3 and increases, during the first year of life, to about 961 cm 3, after which the growth rate declines. Brain volume peaks at the teenage years, [ 34 ] and after the age of 40 it begins declining at 5% per decade, speeding up around 70. [ 35 ]
A newborn's head is very large in proportion to the body, and the cranium is enormous relative to his or her face. While the adult human skull is about one seventh of the total body length, the newborn's is about 1 ⁄ 4. Normal head circumference for a full-term infant is 33–36 cm at birth. [6]
The greatest circumference of the head, which corresponds to the plane of the occipitofrontal diameter, averages 34.5 cm (13.6 in), a size too large to fit through the pelvis without flexion. The smallest circumference, corresponding to the plane of the suboccipitobregmatic diameter, is 32 cm (13 in).
Infants with microcephaly are born with either a normal or reduced head size. [10] Subsequently, the head fails to grow, while the face continues to develop at a normal rate, producing a child with a small head and a receding forehead, and a loose, often wrinkled scalp . [ 11 ]
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Cranial vault size is directly proportional to skull size and is developed early. [1] The size and shape of the brain and the surrounding vault remain quite plastic as the brain grows in childhood. In several ancient societies, head shape was altered for aesthetic or religious reasons by binding cloth or boards tightly around the head during ...