The cephalocaudal trend, or cephalocaudal gradient of growth, refers to the pattern of changing spatial proportions over time during growth. One example of this is the gradual change in head size relative to body size during human growth. During
prenatal growth
Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...
, from conception to 5 months, the head grows more than the body. In humans, the head comprises almost 50% of total body length at approximately the third month of
intrauterine
The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The uter ...
development. By the time of birth the head has decreased to approximately 30% of total body length as a result of the limbs and trunk growing faster than the head. This trend continues
postnatal
The postpartum (or postnatal) period begins after childbirth and is typically considered to end within 6 weeks as the mother's body, including hormone levels and uterus size, returns to a non-pregnant state. The terms puerperium, puerperal perio ...
ly along an axis of increased growth from the head to the feet. Finally, in adults, the head represents approximately 12% of the body length. The cephalocaudal trend is also the trend of infants learning to use their
upper limb
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulde ...
s before their
lower limb
The human leg, in the general word sense, is the entire lower limb of the human body, including the foot, thigh or sometimes even the hip or gluteal region. However, the definition in human anatomy refers only to the section of the lower limb ext ...
s. The proximodistal trend, on the other hand, is the prenatal growth from 5 months to birth when the fetus grows from the inside of the body outwards. When referring to
motor development
A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or indirectly ...
, the proximodistal trend refers to the development of
motor skill
A motor skill is a function that involves specific movements of the body's muscles to perform a certain task. These tasks could include walking, running, or riding a bike. In order to perform this skill, the body's nervous system, muscles, and br ...
s from the center of the body outwards.
References
*Berk, L. E. (2008). ''Infants, children, and adolescents'' (6th ed). Boston: Pearson Education, Inc.
*roben adjadan (2015) ''Contemporary Orthodontics'' (4th ed). Missouri: mati city, Inc.
*Contemporary Orthodontics (5th ed)
Child and adolescent psychiatry
Child development