The question of when the head stops growing does not have a single, simple answer because the head is made up of two distinct skeletal components—the upper brain case (neurocranium) and the lower facial structure (viscerocranium)—that mature at different rates. The neurocranium largely finishes its main phase of growth in early childhood to accommodate the rapidly expanding brain. In contrast, the facial skeleton undergoes a prolonged period of development, continuing well into late adolescence and early adulthood.
The Cranium’s Growth Timeline
The neurocranium, which forms the protective shell around the brain, follows a rapid growth curve that is directly linked to neural development. At birth, a newborn’s skull is composed of several separate plates joined by flexible fibrous joints called sutures, and soft spots known as fontanelles. This flexibility allows for safe passage through the birth canal and accommodates the brain’s initial explosive growth phase.
The brain reaches approximately 90% of its adult size by the time a child is between five and seven years old. Correspondingly, the cranial vault achieves near-adult volume by this same early childhood period. The initial growth phase is one of expansion, where the bone plates are passively pushed outward by the growing brain, with new bone deposited at the sutural margins to fill the gaps.
While the brain case volume is largely set by this age, the complete fusion of the major cranial sutures occurs much later, sometimes continuing for decades. For example, the metopic suture, which separates the frontal bones, typically fuses in infancy. However, other sutures, such as the sagittal suture running along the top of the head, may not fully obliterate until a person is in their twenties or even thirties.
Facial Bone Development and Maturity
In stark contrast to the early maturation of the cranium, the facial bones (viscerocranium) continue to grow and reshape throughout the teenage years. This prolonged development is responsible for the transition from a child’s round face to the more defined features of an adult. The growth of the midface, which includes the maxilla and nasal structures, proceeds at a steady, slower pace than the brain case.
The maxilla (upper jaw) moves downward and forward relative to the cranial base, with much of its growth complete by the mid-adolescent years. The most protracted growth occurs in the mandible (lower jaw), which contributes significantly to the final adult profile. Mandibular growth involves bone deposition at the condyle and remodeling along the jawline, often resulting in a more prominent chin and jaw angle.
Skeletal maturity in the face is reached at different times for males and females, which is a key factor in the final timing of head growth cessation. Females typically complete their facial skeletal growth around 17 years of age. Males, however, often see continued growth of the mandible until about 21 or 22 years old, leading to a later finalization of their facial structure.
Hormonal Influence on Skeletal Maturation
The signal for the end of major skeletal growth, including the head, is driven by the surge of sex hormones during puberty. These hormones, primarily estrogen and testosterone, regulate the closure of growth centers. In the skull, a significant growth center is the spheno-occipital synchondrosis, a cartilage plate located at the base of the skull.
This synchondrosis, which functions similarly to the epiphyseal plates in long bones, is responsible for increasing the length of the cranial base. Estrogen and testosterone cause the cartilage in these plates to be replaced by bone, a process called synostosis. The timing of this closure is directly linked to the pubertal growth spurt.
The spheno-occipital synchondrosis typically fuses in females between the ages of 13 and 15, and slightly later in males, usually between 15 and 17 years. The earlier and more rapid rise in estrogen in females accelerates this process, explaining why females reach skeletal maturity sooner than males. Once this foundational growth plate is closed, the overall expansion of the skull base ceases.
Subtle Structural Changes in Adulthood
Even after the main growth phases conclude, the bony structure of the head continues to undergo subtle changes throughout adulthood. Bone is a living tissue that constantly remodels through a balanced process of resorption (breaking down old bone) and deposition (forming new bone). This remodeling is a lifelong response to mechanical stress and biological signals.
In the facial skeleton, this process manifests as localized changes that contribute to the appearance of aging. For example, specific areas of the maxilla and orbital rims tend to undergo bone resorption, which can cause a loss of projection in the midface and a change in the shape of the eye sockets. The mandible also remodels, particularly in the prejowl area, which can make the lower face appear less supported over time.
Additionally, while bone growth stops, cartilage continues to change throughout life. The cartilage in the nose and ears does not ossify and appears to elongate slowly over the decades. This continuous, albeit minor, reshaping means that while the head’s primary skeletal growth is complete in early adulthood, its form never entirely stops evolving.